Patents > Guidance, Tools, and Manuals >> Classification >>> Class Definition

Class Numbers & Titles   | Class Numbers Only   | USPC Index   | International   | HELP

You are viewing a Class definition.

CLASS 250,	RADIANT ENERGY
Click here for a printable version of this file

SECTION I - CLASS DEFINITION

This is the residual class for methods and apparatus involving radiant energy.

SCOPE OF THE CLASS

This class provides for all methods and apparatus for using, generating, controlling or detecting radiant energy, combinations including such methods or apparatus, subcombinations of same and accessories therefore not classifiable elsewhere.

SECTION II - LINES WITH OTHER CLASSES AND WITHIN THIS CLASS

Many other classes provide for methods and apparatus involving radiant energy, per se, or in combination when such methods or apparatus are also the subject matter of the class in question.

In general, subject matter involving radiant energy is provided for in other classes on the basis of either a specific use of the radiant energy or a specific type of radiant energy. Classes explicitly providing for subject matter involving radiant energy are listed below and arranged according to the above described basis of classification followed by some miscellaneous classes.

CLASSES PROVIDING FOR SPECIFIC USES OF RADIANT ENERGY

See References to Other Classes for the following art areas:

Uses of Radiant Energy for Separating and Assorting

Uses of Radiant Energy for Treating

Uses of Radiant Energy As a Medium of Control

Uses of Radiant Energy for Testing

Uses of Radiant Energy As a Medium of Communication

CLASSES PROVIDING FOR SPECIFIC TYPES OF RADIANT ENERGY

Classes Providing for Electron Space Discharge Type of Radiant Energy

Visible Light Type

Other Wave Type

SECTION III - REFERENCES TO OTHER CLASSES

SEE OR SEARCH CLASS:

SECTION IV - GLOSSARY

CIRCUIT

A closed or closable conducting path through which, or along which, electric current can travel.

DETECTOR

A material or device whose response to radiant energy is used to indicate the presence or amount of incident radiation. Also, called "Signalling Means".

FLUENT MATERIAL

A liquid, gas or mass of granular solid material that does not of itself maintain its own spatial form but flows. Whether or not a granular material should be considered fluent or not is determined in each case by how it is handled. Generally if the handling means has walls to hold up the material, the material is fluent. Thus, for example, coal is necessarily fluent in a pail or bin but not necessarily fluent in a pile.

ION

An atom or molecule with at least one more or less electrons than protons. Electrons, per se, are not considered ions.

IONIZATION

The process of adding to or removing from an electrically neutral atom or molecule one or more of its electrons. Note: Ionization, as sometimes used to denote the process of increasing the energy level of an atom or molecule to some state short of the above, is not encompassed by this definition. Such processes in this class are considered partial or incomplete ionization.

INSPECTION

A term implying a source of radiant energy, and/or means to irradiate an object by said source and a detector responsive to radiation from the object to provide a signal representing some characteristic of the object.

OBJECT

A material subjected to radiation for treatment or whose response to or effect on the radiation is used to indicate something about the material.

PHOTOCELL

A detector used to sense light incident thereon and generate a signal representative of some aspect of the light such as intensity, phase, coherence, mode distribution, interference pattern characteristics, etc.

PHOTODETECTOR

See Photocell

PHOTOELECTRIC CELL

See Photocell

PHOTOSENSOR

See Photocell

RADIANT ENERGY

Energy propagated in the form of electromagnetic waves, or traveling subatomic, atomic or molecular particles.

RADIOACTIVE ACTIVE

Exhibiting spontaneous nuclear disintegration with emission of particulate or electromagnetic radiations.

SIGNALING MEANS, ELECTRIC AND NONELECTRIC

Detectors that produce in response to incident radiant energy either an increase or decrease in electric potential or current flow (Electric) or some other perceivable change (Nonelectric). The nonelectric change may be immediately perceived or may require development to be perceived, e.g., photographic changes.

SUBCLASSES

200	PHOTOCELLS; CIRCUITS AND APPARATUS:
	This subclass is indented under the class definition.  Subject matter which includes a photocell. (1) Note. DEFINITION OF TERMS: A photocell is defined for the purpose of classification in these subclasses as an electrical device which responds to light by varying its electrical characteristics or by generating an electric current. This definition therefore includes resistances, electric space discharge devices, batteries, inductances, condensers, bolometers and other electrical devices which have their electrical characteristics varied by radiant energy. For the purpose of classification in these subclasses "light" and "radiant energy" are used synonymously. (2) Note. CIRCUITS AND APPARATUS INCLUDED: These are the generic subclasses for the following: a. Electrical circuits whose operations are controlled by means of a photocell. b. Electrical systems for supplying electric current and/or potential to a photocell. c. Photocells in combination with the optical means for controlling the radiant energy which illuminates the photocell. d. Photocells in combination with the source of illumination for the photocell. e. Apparatus which is limited to use with photocells and which is not otherwise classified. Examples of such apparatus are the photocell temperature control means in subclass 238 and the housings in subclass 239. (3) Note. SIGNALING SYSTEMS: Electrical communication systems whose operation is controlled by means of a photocell are excluded from these subclasses. For such systems see the Search Class notes below. (4) Note. PHOTOCELL CONTROLLED CATHODE-RAY TUBE CIRCUITS See the Search Class notes below for Photocell Controlled Cathode-ray Tube Circuits (5) Note. PHOTOCELL COMBINED WITH DIVERSE TYPE DEVICE: These subclasses include a photocell apparatus or photocell controlled circuit when combined with a diverse type apparatus only when the combination includes only the portion of the diverse type apparatus necessary to provide for the photocell apparatus or circuit. Such combinations will be found for the most part in subclass 215 of this class. Where structure of the device is claimed in addition to that necessary to provide for the photocell apparatus or photocell circuit, the device is excluded from these subclasses and will be found with the art that provides for the particular device with which the photocell is combined. Also, see (6) Note below with reference to photocell circuits which are limited to controlling specific devices, such as a signal, meter, etc. See (3) Note above for a reference to signaling systems which include a photocell. For some of the classes which provide for devices which include a photocell apparatus or circuit, see the classes listed under (9) Note below. (6) Note. PHOTOCELL CIRCUIT WITH SPECIFIC LOAD DEVICE IN THE OUTPUT CIRCUIT: a. General Statement: These subclasses do not provide for photocell controlled circuits which have a particular load device, such as an electric motor, recited in the output circuit. Such systems are classified with the particular art. See the paragraphs below for some special exceptions to this general statement. For a partial list of the classes which provide for the excluded circuits, see the classes under (9) Note below. b. Photocell controls its light source or optical system: These subclasses do provide in subclasses 201+ for photocell circuits where the output circuit controls means which control the optical system of the photocell, (e.g., rebalancing systems, apparatus having means for causing the photocell to move so as to trace the contour of a pattern, circuits having the illumination source for the photocell controlled by the photocell). Note that where the claims are limited to a photoelectric circuit having an electric lamp as the source of illumination for the photocell, the electric lamp being connected in the output circuit of the photocell circuit so that the lamp which illuminates the photocell is controlled by the photocell, no structure of the optical system between the lamp and photocell being claimed, the circuit is classified in Class 315, Electric Lamp and Discharge Devices: Systems, subclass 151. c. Photocell with electronic tube or other current or potential modifying means in the output circuit. These subclasses do provide for photocell circuits having means in the output circuit for modifying or amplifying the photocell current or voltage so as to produce the type of output control current or voltage desired. Examples of such means are the bridge circuits and electronic tube devices. Where the disclosure relates to a plurality of species of relay systems of which one is an electronic relay (electronic tube) system and the claims recite the relay in generic terms, classification is in Class 361, subclasses 173+. Where the claims are limited to an electronic relay or the disclosure relates only thereto even though the relay is recited broadly, classification is herein (Class 250). If such optical system is claimed, the subject matter is classified in Class 250, subclasses 200+. Where the device controlled in the output circuit is a cathode-ray tube, or where the photocell is a part of a cathode-ray tube and the claims do not include any significant output circuit for the cathode-ray tube, the circuit is classified in Class 315, Electric. Lamp and Discharge Devices: Systems, subclasses 10+. See (4) Note above. Where the device controlled in the output circuit is an electronic tube of the gas or vapor type (including gas or vapor discharge lamps), and the claims do not include any significant output circuit for the electronic tube, the circuit is classified in Class 315, Electric Lamp and Discharge Devices: Systems, subclasses 149+, especially in subclasses 156 and 157. Subclass 156 provides for the circuit where another electronic tube which is controlled by the photocell is interposed in the supply circuit of the gas or vapor type electronic tube, and subclass 157 where the electronic tube which is controlled is provided with a discharge control means (e.g., grid). d. Photoelectric visible light examination apparatus. The analysis of visible light by means of a photosensitive detector coupled to a recorder or meter is in Class 356. The analysis of light and including a photosensitive detector, but not including a meter, recorder or other indicator is classified in Class 250. The examination of solid, liquid or gaseous material or articles for an optical property, light scattering flaws, or size and configuration tests are in Class 356. A support for material or an article being examined and a photosensitive device to detect variation in visible light caused by the examined material is classified in Class 356, providing the disclosure involves the examination of the material or the article by visible light. The examination of material by visible light involving a photoelectric detection of the light as affected by the material and an electrical alarm is in Class 340, subclasses 619+. (7) Note. PHOTOCELLS, PER SE: These subclasses do not include the structure of the photocell, per se. The photocells, per se, are classified according to the type of electrical device. For the classes and subclasses which provide for photocells and analogous devices, see the Search Class notes below. (8) Note. TO COMPLETE THE SEARCH FOR THIS SUBJECT MATTER, see the Search This Class, Subclass and Search Class notes below. SEE OR SEARCH THIS CLASS, SUBCLASS: 336.1+, where the photocell has characteristics which cause it to respond principally to the invisible portion of the radiation spectrum or where the photocell is combined with means to insure that it will respond to the invisible portion of the radiation spectrum. Illustrative of such photocells are a Geiger-Mueller counter and a conventional photocell provided with an ultraviolet ray filter, respectively. Where the photocell will respond to both visible and invisible radiant energy and is not provided with means for enhancing response to invisible radiant energy or diminishing response to visible radiant energy, classification is in subclasses 200+ (see (8) note above). 354.1, for photocell means to control the amount of invisible radiation falling on the photocell. SEE OR SEARCH CLASS: 15,  Brushing, Scrubbing, and General Cleaning,   subclass 319 , with automatic control. 19,  Textiles: Fiber Preparation,   photoresponsive control of stopping fiber preparation apparatus. 33,  Geometrical Instruments,   subclass 363 , electrical telemetering with a photoelectric pickoff; subclass 707, distance, including optical. (see (9) note above). 40,  Card, Picture, or Sign Exhibiting,   subclasses 465+ for special effects displays with photoelectric switching. 49,  Movable or Removable Closures,   subclass 25 , radiant energy control, and subclasses 197+, photocell control of an up-and-over closure opener. 60,  Power Plants,   subclasses 233+ , condition responsive thrust bearing means for reaction motors; subclass 254, solid propellant type reaction motors including means to regulate or terminate motive fluid production. 62,  Refrigeration,   subclasses 139 and 140, automatic control by accumulation of ice or frost. 72,  Metal Deforming,   subclasses 6+ control means stimulated by condition responsive, including condition responsive sensor. 73,  Measuring and Testing,   subclasses 23, 23.1, 53+ including 61.4, 73+, 104, 151+, 861+, and 290 for measuring and testing involving, inter alia, radiant energy detection; subclass 705, photoelectric fluid projector gauge. 84,  Music,   subclasses 639 and 724 for musical instruments in which the sound is produced from electric currents which are generated or controlled by photocells or for the photocell subcombinations of such musical instruments, when restricted to such use. 89,  Ordnance,   subclass 41.06 for operation by photocell control of certain motors. 96,  Gas Separation: Apparatus,   subclasses 417+ for gas separation apparatus with signals, indicators, measuring, or testing means. 99,  Foods and Beverages: Apparatus,   subclass 342 , with signal, indicator, or tester. 112,  Sewing,   subclasses 80.23+ , for embroidery with optical pattern program means; subclasses 470.01+ for pattern control means. 118,  Coating Apparatus,   subclass 691 , photoelectric sensor responsive to condition of coated material. 134,  Cleaning and Liquid Contact With Solids,   subclass 56 , automatic controls, and subclass 113, with, inter alia, testing, inspecting or illuminating means. 136,  Batteries: Thermoelectric and Photoelectric,   subclasses 213+ for photocells of the radiation pyrometer type which generate electricity by virtue of the heating effect of radiant energy and which may contain optical means; subclasses 243+ for photocells of the primary battery type which depend upon the presence of visible radiant energy for their operation; and subclasses 291 for applications of these photocells (see Photocells, Per Se; (7) note above). 137,  Fluid Handling,   subclass 78.1 , ambient condition responsive; subclass 93, sensing condition opically. 141,  Fluent Material Handling With Receiver Coacting Means,   subclasses 192+ , automatic cutoff or diversion control. 160,  Flexible or Portable Closure, Partition, or Panel,   subclass 5 for closures, partitions or panels which are automatically controlled by a photocell. 162,  Paper Making and Fiber Liberation,   subclass 263 , measuring, testing inspecting, indicating or illumination. 164,  Metal Founding,   subclass 4.1 , with measuring, testing, inspecting or condition sensing. 166,  Wells,   subclasses 250+ , with indicating, testing, measuring or locating. 175,  Boring or Penetrating the Earth,   subclass 41 , combined with ray energy detection or measuring. 178,  Telegraphy,   subclass 70 , photocell repeaters (see Signaling Systems; 3 Note above). 187,  Elevator, Industrial Lift Truck, or Stationary Lift for Vehicle,   subclass 317 for an electric control for an elevator door having a position detector mounted on the door and subclass 392 for an elevator with a position detector for monitoring passengers. 192,  Clutches and Power-Stop Control,   subclass 29 , photocell control of stop; subclass 142, radio tuner stop control. 198,  Conveyors: Power-Driven,   subclasses 356+ , with condition responsive control means, especially subclass 358, sensing condition of source or destination. 209,  Classifying, Separating, and Assorting Solids,   subclasses 509+ , especially subclasses 576+, for devices containing a photocell, which will classify, separate or assort objects in accordance with their optical properties or their appearance, such as glossiness, color or size. 210,  Liquid Purification or Separation,   subclass 745 , process control by optical sensing of condition. 219,  Electric Heating,   subclass 121.6 laser beam position control. 227,  Elongated-Member-Driving Apparatus,   subclasses 2+ , with control means responsive to sensed condition. 235,  Registers,   subclasses 400+ , ordnance or weapons computer, including subclass 411, with target tracking means; subclasses 375+, systems controlled by data bearing members. 241,  Solid Material Comminution or Disintegration,   subclasses 33+ with automatic control. 242,  Winding, Tensioning, or Guiding,   subclasses 331.4 , 410+, 472.9+, 479.9+, 484.8, 484.9+, 534+, and 563+ for a detector or stop for regulating winding, unwinding, or tensioning of an elongated material. 244,  Aeronautics and Astronautics,   subclasses 3.1+ , missile stabilization or trajectory control using radiant energy. 246,  Railway Switches and Signals,   subclass 29 for railway traffic control systems which are controlled by a photocell (see Signaling Systems; 3 Note above). 252,  Compositions,   subclass 501.1 contains photosensitive resistance compositions (see Photocells, per se; (7) note above). 257,  Active Solid-State Devices (e.g., Transistors, Solid-State Diodes),   subclasses 10 , 11, 21, 53-56, 113-118, 184-189, 225-234, 257, 258, 290-294, and 414-466 for radiation-sensitive active semiconductors devices (see Photocells, per se; (7) note above). 264,  Plastic and Nonmetallic Article Shaping or Treating: Processes,   subclasses 408+ , measuring, testing or inspecting by passing light through material. 307,  Electrical Transmission or Interconnection Systems,   subclass 117 , radiant energy responsive switching systems; subclass 10.8, vehicle mounted light system (see Signaling Systems; 3 Note above). 313,  Electric Lamp and Discharge Devices,   subclasses 364+ for photosensitive cathode-ray tubes, and subclasses 523+ for other photosensitive discharge devices (see Photocells, per se; (7) note above). 314,  Electric Lamp and Discharge Devices: Consumable Electrodes,   subclass 63 for arc lamps in which the feeding of the electrodes is controlled by a photocell. 315,  Electric Lamp and Discharge Devices: Systems,   subclasses 10+ , with radiant energy sensitive control means, subclasses 82+ for vehicle headlamp as by dimming when the photocell is illuminated by the headlamps of another vehicle, and subclass 134, with signal indicator or alarm readout energy responsive control. 315,  Electric Lamp and Discharge Devices: Systems,   subclasses 10+ for miscellaneous circuits for supplying electric current and/or potential to a cathode-ray tube where the system includes a photocell to control the cathode-ray tube. The systems included in subclasses 10+ include systems having a photocell in the supply circuit of the cathode-ray tube and systems where the cathode-ray tube includes a photoelectric electrode (see Photocell Controlled Cathode-ray Tube Circuit: (4) note above). 315,  Electric Lamp and Discharge Devices: Systems,   subclasses 10+ for photocell controlled cathode-ray tube circuits. See (4) and (6c) Notes, supra. Subclass 134 provides for indicator or alarm signal in an electron tube circuit controlled by a photoelectric cell. Subclasses 149+ provide for photocell circuits which control an electric lamp or an electronic tube of the gas or vapor type. See subclass 150 where the lamp or gas or vapor tube is itself a photocell, subclass 151 where the lamp which illuminates the photocell is in the output circuit of the photocell, (see (6) Note, b, above and subclasses 156 and 157 where the photocell controls the operation of a gas or vapor type electronic tube or lamp (see (6) Note, c, above). 318,  Electricity: Motive Power Systems,   subclasses 560+ , particularly subclass 640 for electric motor position servo systems which may be responsive to a photocell; subclasses 576+, particularly subclass 577 for electric motor systems in which a photocell senses a pattern and controls the motor in accordance with the sensing; and subclass 480 for other photocell controlled electric motor systems. 322,  Electricity: Single Generator Systems,   subclass 26 for electric generator systems having a generator and a photocell which controls the generator or the driving means for the generator. 323,  Electricity: Power Supply or Regulation Systems,   subclass 221 for voltage magnitude control systems having a photocell which automatically controls the system. 324,  Electricity: Measuring and Testing,   subclass 344 , using a radiant energy receiver for geological measurement or test; subclass 96, light detector. 327,  Miscellaneous Active Electrical Nonlinear Devices, Circuits, and Systems,   subclasses 509+ for miscellaneous circuits responsive to radiant energy (see Signaling Systems; (3) note above.) 338,  Electrical Resistors,   subclasses 15+ for electrical resistors, per se, whose resistance value changes in response to a change in light intensity, e.g., photoconductive type electrical resistors (see Photocells, Per Se; (7) note above). 330,  Amplifiers,   subclass 59 , light controlled or activated device. 331,  Oscillators,   subclass 66 , light responsive ambient condition sensor. 335,  Electricity: Magnetically Operated Switches, Magnets, and Electromagnets,   subclasses 2+ , electromagnetically actuated switches. 337,  Electricity: Electrothermally or Thermally Actuated Switches,   subclasses 298+ for thermally responsive switches (see Photocells, Per Se; (7) note above). 338,  Electrical Resistors,   subclasses 15+ for light responsive electrical resistors. 340,  Communications: Electrical,   subclasses 902+ for vehicle carried photocell system; subclasses 870.28+, for telemetering via light beam; subclasses 500+ for photocell controlled condition responsive devices; e.g., alarms; subclass 942, for photoelectric vehicle detectors. 340,  Communications: Electrical,   for miscellaneous signaling systems controlled by a photocell. Note especially subclasses 901+ for a vehicle carried photocell system, subclass 870.29 for telemetering via a light beam, and subclass 600 for a condition sensing photocell which actuates a signal or alarm (see Signaling Systems; (3) note above.) 341,  Coded Data Generation or Conversion,   subclasses 1+ , digital pattern reading converter, especially subclasses 13, optical, and subclass 14, optical waveguide, and subclass 31, photoelectric actuated keyboard code generator (see Signaling Systems; (3) note above.) 342,  Communications: Directive Radio Wave Systems and Devices (e.g., Radar, Radio Navigation),   subclasses 52+ , with diverse type radiant energy system. 345,  Computer Graphics Processing and Selective Visual Display Systems,   subclasses 180+ for light pen input to selective visual display communication systems. 346,  Recorders,   subclass 33 , combined with external optical system recorder operating means. 348,  Television,   subclasses 207.99 through 207.2and 332 for television system which may include a photocell (see Signaling Systems; (3) note above), and subclasses 602-603 for photocell controlled cathode-ray tube. 360,  Dynamic Magnetic Information Storage or Retrieval,   subclass 31 for monitoring or testing recording progress; subclass 74.6 for photoelectric stopping or reversing control; and subclasses 114.01-114.1 for reproducing only, using light. 351,  Optics: Eye Examining, Vision Testing and Correcting,   subclass 210 , using photodetector to detect eye movement. 352,  Optics: Motion Pictures,   subclass 140 , focus control; and subclass 141, automatic diaphragm control. 353,  Optics: Image Projectors,   subclasses 25+ , selective data retrieval. 355,  Photocopying,   subclasses 55+ , photodetector used with focus or magnification control; subclass 41, identifying, composing or selecting using photocell; subclass 38, color film exposure or light intensity control; subclasses 203+, photocopiers with diagnostic testing; subclass 68, illumination system including photocell. 356,  Optics: Measuring and Testing,   particularly subclasses 300+ for photoelectric spectroscopic apparatus, subclass 450 for photoelectric interference type test apparatus, subclasses 364+ for polarized light tests, subclasses 128+ for photoelectric refraction test apparatus, subclasses 402+ for shade or color tests, subclasses 433+ for light transmission tests, subclasses 445+ for light reflection tests, subclasses 218+ for photoelectric type photometers, and subclasses 237.1+ for photoelectric flaw testing apparatus. 358,  Facsimile and Static Presentation Processing,   subclass 161 for control of brightness or contrast of display on cathode-ray tube dependent on ambient light sensed by photocell, and subclasses 400-304 for facsimile and subclasses 471-498 for facsimile systems which may include a photocell (see Signaling Systems; (3) note above.) and for photocell control of a cathode-ray tube in facsimile systems (see Photocell Controlled cathode-ray Tube Circuit: (4) note above). 359,  Optical: Systems and Elements,   subclasses 107 through 108for optical computing, subclasses 507-514, for foreign particle control of optical elements or systems. 360,  Dynamic Magnetic Information Storage or Retrieval,   subclass 31 for monitoring or testing recording progress; subclass 74.6 for photoelectric stopping or reversing control; and subclasses 114.01-114.1 for reproducing only, using light. 361,  Electricity: Electrical Systems and Devices,   subclasses 173+ for photocell controlled relay and electromagnet circuits. See (6) Note. c, above. 362,  Illumination,   subclasses 276 and 277+ for illuminating means having a movable screen which is automatically controlled by a photocell, and subclass 4, light responsive photographic lighting. 363,  Electric Power Conversion Systems,   subclasses 125+ for rectifying systems having rectifiers of the selenium type, analogous to selenium photocells. 365,  Static Information Storage and Retrieval,   subclasses 106+ , radiant energy; subclasses 215+, optical read-write circuits; subclasses 234+, optical address (see Signaling Systems; (3) note above.) 367,  Communications, Electrical: Acoustic Wave Systems and Devices,   subclass 64 , optical processing of seismic signals; subclasses 140+, signal transducer (see Signaling Systems; (3) note above.) 369,  Dynamic Information Storage or Retrieval,   subclasses 100+ for electrical sound recording and reproducing systems which include a photocell (see Signaling Systems; (3) note above.) 369,  Dynamic Information Storage or Retrieval,   subclasses 44+ , optical transducers; subclasses 100+, radiation beam modification by storage medium. 370,  Multiplex Communications,   subclasses 1+ , optical (see Signaling Systems; (3) note above.) 370,  Multiplex Communications,   subclasses 1+ , optical. 379,  Telephonic Communications,   appropriate subclasses, for electric sound recording and reproducing, using photocells (see Signaling Systems; (3) note above.) 365,  Static Information Storage and Retrieval,   subclasses 106+ , radiant energy; subclasses 215+, optical read-write circuits; subclasses 234+, optical address. 367,  Communications, Electrical: Acoustic Wave Systems and Devices,   subclass 64 , optical processing of seismic signals; subclasses 140+, signal transducer. 368,  Horology: Time Measuring Systems or Devices,   subclass 11 , ambient light sensor. 372,  Coherent Light Generators,   subclasses 9+ , particular beam control device. 374,  Thermal Measuring and Testing,   subclasses 121+ for temperature measurement by an arrangement responsive to thermally emitted radiation by the body whose temperature it measured. 376,  Induced Nuclear Reactions: Processes, Systems, and Elements,   subclass 248 , testing reactor condition using optics. 377,  Electrical Pulse Counters, Pulse Dividers, or Shift Registers: Circuits and Systems,   subclass 53 , with photoelectric detector; subclass 6, counting inanimate entities. 378,  X-Ray or Gamma Ray Systems or Devices,   subclasses 97 and 108 for source control in response to detecting radiation therefrom. 382,  Image Analysis,   all subclasses. 396,  Photography,   subclasses 549+ for phototype composing, subclasses 89+ for automatic camera focussing with photoelectric control; subclasses 213+ for automatic exposure control; and subclass 570 for photocell controlled fluid-treating means. 400,  Typewriting Machines,   subclasses 706+ , for indicating position of line or end of page, including detector of record medium. 409,  Gear Cutting, Milling, or Planing,   subclass 128 , tracer adapted to trigger a photocell. 422,  Chemical Apparatus and Process Disinfecting, Deodorizing, Preserving, or Sterilizing,   subclasses 50+ , analyzer, indicator or manipulative laboratory device; subclass 162, automatic analytical monitor and control of industrial products; subclass 85, with color change; subclass 91, gas analysis with absorption and with photometric detector; subclass 106, control element responsive to sensed liquid level. 424,  Drug, Bio-Affecting and Body Treating Compositions,   subclasses 9.1+ for in vivo diagnosis and testing compositions and subclasses 10.1+ for Class 424 compositions with an identification or warning feature. 427,  Coating Processes,   subclass 10 , optical measuring, testing and indicating. 434,  Education and Demonstration,   subclasses 1+ , electromagnetic sensor to detect or determine range; subclasses 112+, communication aids for handicapped; subclass 187, measurement of length or volume; subclass 240, radio navigation with light sensor in simulator; subclass 303, science, physics, optics; subclass 325, image projector and light detector used in question or problem; subclass 337, correctness of response using light detector; subclasses 355 and 358, grading a response using light sensor. 435,  Chemistry: Molecular Biology and Microbiology,   subclass 288.7 for optical sensing apparatus; and subclasses 4+ for measuring or testing. 436,  Chemistry: Analytical and Immunological Testing,   subclasses 164+ , optical result; subclass 805, optical property. 438,  Semiconductor Device Manufacture: Process,   particularly subclass 7 for methods of making semiconductor devices having a step controlled in response to a sensed optical condition and subclass 16 for methods having a step of measuring an optical condition. 446,  Amusement Devices: Toys,   subclass 175 , having light or sound responsive switch or control. 455,  Telecommunications,   subclasses 600+ , for lightwave communication (see Signaling Systems; (3) note above.) 463,  Amusement Devices: Games,   subclasses 51+ for a game in which an electromagnetic ray (e.g., a light ray, etc.) is used to simulate a projectile fired from a gun, torpedo launcher, etc., which game may include a photocell (often as part of a target for the gun, torpedo launcher, etc. 493,  Manufacturing Container or Tube From Paper; or Other Manufacturing From a Sheet or Web,   subclasses 3+ , condition responsive control means, especially subclass 10, using photocell. 505,  Superconductor Technology: Apparatus, Material, Process,   subclasses 150+ for high temperature (Tc greater than 30 K) superconducting devices, subclasses 300+ for processes of producing high temperature superconductor or superconductive devices, particularly subclasses 320, 325, and 480+ for use of radiant energy or particle bombardment; and cross-reference art collections 842+ for superconductor measuring and testing. 600,  Surgery,   subclasses 300+ for diagnostic testing. 702,  Data Processing: Measuring, Calibrating, or Testing,   appropriate subclasses. 703,  Data Processing: Structural Design, Modeling, Simulation, and Emulation,   subclass 3 for analog computer simulation of physical phenomena (see Signaling Systems; (3) note above). 708,  Electrical Computers: Arithmetic Processing and Calculating,   subclass 816 for optical correlation or convolution (see Signaling Systems; (3) note above). 901,  Robots,   subclass 47 , optical sensing device. 902,  Electronic Funds Transfer,   subclass 41 , with means to read data stored on identifier.

201.1	Photocell controls its own optical systems:
	This subclass is indented under subclass 200.  Subject matter in which the photocell automatically controls the illumination which falls on the photocell by altering optical means located between a source of illumination and the photocell or by altering the illumination source. (1) Note. The control of the illumination may be achieved by altering the source of light (e.g., intensity or position) or by altering the optical path between source of light and photocell (e.g., transparency of light transmitting medium or position of photocell or optics). SEE OR SEARCH THIS CLASS, SUBCLASS: 205, for photocell controlled circuits for controlling light source intensity. 206.1+, for photocell controlled circuits or devices which do not control the illumination of the photocell. 216+, for optical systems which control the illumination of a photocell.

201.2	Automatic focus control:
	This subclass is indented under subclass 201.1.  Subject matter in which at least one photocell is used to automatically adjust a lens to form a distinct image of an object on an imaging surface. SEE OR SEARCH CLASS: 396,  Photography,   subclasses 89+ for automatic camera focussing having photoelectric control.

201.3	Of a microscope:
	This subclass is indented under subclass 201.2.  Subject matter in which the focusing of the light image in a microscope is controlled. SEE OR SEARCH CLASS: 359,  Optics: Systems (Including Communication) and Elements,   subclasses 368+ , for optical microscopes, per se.

201.4	Active autofocus:
	This subclass is indented under subclass 201.2.  Subject matter having means to illuminate the object with light other than, or supplementary to, ambient light. (1) Note. Optical elements or systems of optical elements, e.g., reflectors, used to concentrate or otherwise intensify ambient illumination are encompassed by active autofocus illumination means. SEE OR SEARCH CLASS: 396,  Photography,   subclasses 106+ for automatic camera focussing using active ranging, for related subject matter when the camera structure is claimed as well as active focussing means.

201.5	With optical storage medium; e.g., optical disc, etc.:
	This subclass is indented under subclass 201.4.  Subject matter in which the image is formed on the surface of an optical information storage or retrieval medium, e.g., an optical disc. SEE OR SEARCH CLASS: 369,  Dynamic Information Storage or Retrieval,   subclass 45 for patents claiming details of the optical storage medium or writing or reading of information to or from the medium, and subclasses 100+ for optical details of the optical information storage and retrieval system.

201.6	Based on triangulation:
	This subclass is indented under subclass 201.2.  Subject matter in which the focusing is based on geometric triangulation using a baseline distance between at least two photocells. (1) Note. This subject matter differs from that in Class 356, subclasses 3.01+ in that subject matter in this subclass provides for triangulation to achieve automatic focus control of an optical pre-photocell system whereas subject, matter in Class 356, subclasses 3.01+ uses triangulation to measure the distance of an object from the photocell or pre-photocell system.

201.7	Based on contrast:
	This subclass is indented under subclass 201.2.  Subject matter in which the photo-cell generates signals used to create an image and adjustment of the focus is based on the degree of contrast in all or part of the image, i.e., on the ratio of the darkest and lightest portions of all or part of the image.

201.8	Based on image shift:
	This subclass is indented under subclass 201.2.  Subject matter in which the focusing is based on coincidence of two images of the same object moved in the same plane or of the displacement or distance between different images of the same object in the same plane, e.g., the photodetector plane.

201.9	Light beam wavefront phase adaptation:
	This subclass is indented under subclass 201.1.  Subject matter in which the phases of light waves are sensed and compared, and their sum or difference is used to control the optical system.

202	Following a pattern (e.g., line or edge):
	This subclass is indented under subclass 201.1.  Subject matter having means for illuminating the photocell in accordance with the relative position of the photocell and a pattern, and having means for causing the photocell to follow the edge of the pattern under control of said illumination, or for causing the optical path between pattern and photocell to change, under the control of said illumination, so that the photocell follows the edge of the pattern image. (1) Note. The edge of the pattern may be either a thick or thin line or the line of demarcation between two areas of different optical properties. The photocell may follow the pattern either by moving spatially or by causing the pattern to move past the photocell while the photocell remains stationary. SEE OR SEARCH THIS CLASS, SUBCLASS: 548, for optical systems including a web, strand, strip, or sheet and a photocell controlling same. 559.01+, for optical systems, including a web, strand, strip, or sheet and photocell circuit.

203.1	Following a target (e.g., a star or instrument pointer or other object) other than a pattern:
	This subclass is indented under subclass 201.1.  Subject matter having means for illuminating the photocell in accordance with the relative position of the photoelectric cell and an object, and having means for causing the photoelectric cell to follow the object under the control of said illumination. (1) Note. The object may be a star, a search light at the end of a luminous glide path beam or a spot or an instrument. (2) Note. The photocell must follow the object, as seen through the associated optical system. However, the photocell itself, or the supporting structure, as a whole, need not follow the point, as in a guided missile which is guided towards a terrestrial target by heavenly bodies sensed by a self-carried photocell guiding apparatus. SEE OR SEARCH CLASS: 244,  Aeronautics and Astronautics,   subclass 3.16 , for missile stabilization or trajectory control using optical guidance. 318,  Electricity: Motive Power Systems,   subclass 640 for electric motor follow-up systems wherein the motor control includes a photocell responsive to a moving light point. 346,  Recorders,   subclasses 31 and 32 for photocell systems which control a recorder in accordance with an instrument which operates, free of the mechanical burden, of the recorder, in which the pointer of the instrument is sensed and followed by the photocell, which controls the system which drives the recorder and following means. 382,  Image Analysis,   subclass 60 , image sensing curve tracers for systems that follow the contour of a character as part of an optical character reader. 434,  Education and Demonstration,   subclass 4 , optical radar included in a simulator; and subclass 240, light sensor included in simulator of radio navigation equipment. 463,  Amusement Devices: Games,   subclasses 51+ for a game in which an electromagnetic ray (e.g., a light ray, etc.) is used to stimulate a projectile fired from a gun, torpedo launcher, etc., which game may include a photocell (often as part of a target for the gun, torpedo launcher, etc.) 473,  Amusement Devices: Games,   subclasses 140+ , 151+, 176, 192, and 199 for moving golf ball detection which may involve a photocell.

203.2	Target illuminated by artificial light source:
	This subclass is indented under subclass 203.1.  Subject matter in which the object to be tracked is, as disclosed, illuminated by an artificial light source, e.g., a laser, and the light from that source which is reflected from the target is detected and used to track the object.

203.3	Self-luminous target:
	This subclass is indented under subclass 203.1.  Subject matter in which the object to be tracked emits light which is detected and used to track the object.

203.4	Sun:
	This subclass is indented under subclass 203.3.  Subject matter wherein the self-luminous target to be tracked is the Sun. (1) Note. Since solar radiation is so intense at or near the earth"s surface. Many solar trackers track a shadow cast by an object in between the sun and the photocell. SEE OR SEARCH CLASS: 126,  Stoves and Furnaces,   subclasses 573+ , for solar heat collectors with tracking means controlled by sun position tracking sensor; and subclasses 600+ for means to reposition solar collector for optimum radiation exposure.

203.5	Cathode-ray tube scanning:
	Subject matter under 203.3 in which the self luminous target followed is a spot of light on the face of a cathode-ray tube (CRT).

203.6	Airborne target, or spaceborne target other than the sun (e.g., star or missile):
	This subclass is indented under subclass 203.3.  Subject matter where the self-luminous target is a star or other spaceborne object other than the sun, e.g., a missile exhaust plume. (1) Note. The brightness of these objects is substantially lower than that of the Sun.

203.7	With moving reticle in optical path:
	This subclass is indented under subclass 203.3.  Subject matter in which a moving, e.g., oscillating or rotating, apertured or patterned element is in the optical path between the target and photocell to modulate the light reaching the photocell from the target. (1) Note. A reticle is often used (a) to chop the light reaching the photodetector(s) to permit a-c amplification of the signal generated by the photodetector(s); (b) to aid in distinguishing the target from background illumination; and (c) to generate signals indicative of the position (e.g., azimuth and elevation) of a target. SEE OR SEARCH THIS CLASS, SUBCLASS: 233, rotary light chopping light valves for reticles used to control light reaching a photocell. SEE OR SEARCH CLASS: 359,  Optical: Systems and Elements,   subclasses 234+ for reticles which rotate in an optical path to control light.

204	Adjusting optical system to balance brightness in plural paths:
	This subclass is indented under subclass 201.1.  Subject matter having two optical paths from a source or two sources of illumination to one or more photocells and having means for controlling one or more of the optical paths so that the ratio of light flux which traverses the different optical paths stays constant. SEE OR SEARCH THIS CLASS, SUBCLASS: 208.1+, for similar subject matter having plural photocells in an electric circuit which does not control the illumination reaching the photocells. 578, for photocell illuminating systems having plural light paths to one or more photocells.

205	Controlling light source intensity:
	This subclass is indented under subclass 201.1.  Subject matter having means for controlling the intensity of the light source which illuminates the photoelectric cell in accordance with the illumination which falls upon the photoelectric cell. (1) Note. In addition to the means for controlling the light source, there may be means between the light source and the photoelectric cell to variably divert or absorb the light which passes from the light source to the photocell. Where the sole means for controlling the light which reaches the photoelectric cell is means to variably divert or absorb the light rays, the patent is not classified in this subclass, but will be found in subclasses 201.1 through 204 above. (2) Note. The light source whose intensity may be controlled may be an electric light, a gas flame or any other source of light. SEE OR SEARCH THIS CLASS, SUBCLASS: 201.1, through 204, see (1) Note above. SEE OR SEARCH CLASS: 315,  Electric Lamp and Discharge Devices: Systems,   subclass 151 , where the source of illumination is an electric lamp or gas or vapor discharge device, the photocell controls the electrical condition or electrical characteristics of the source of illumination and there is no significant optical structure in the optical path between source of illumination and photocell.

206	Photocell controlled circuit:
	This subclass is indented under subclass 200.  Subject matter in which the photocell controls an electrical or electro-mechanical system circuit, and systems circuits under subclass 200 for supplying electric current and/or potential to a photocell. (1) Note. In order to be classified in this and indented subclasses, the electrical or electro-mechanical system circuit should be significant. It is significant if it is recited in the claims more specifically than by name only, or if it is disclosed as being nonconventional.

206.1	Having means to generate positional information in at least one plane of a target moving relative to one or more photodetectors:
	This subclass is indented under subclass 206.  Having means to generate positional information in at least one plane of a target moving relative to one or more photodetectors: Subject matter in which photodetecting means generate signals proportional to the position in at least one plane of a target moving relative to the photodetecting means. (1) Note. In order to be classified in this and indented subclasses, the electrical or electromechanical system should be significant. It is significant if it is recited in the claims more specifically than by name only, or if it is disclosed as being nonconventional. (2) Note. Subject matter in this subclass is differentiated from that in subclasses 203+ because in those subclasses, photocell output signals are used to control the pre-photocell optical system whereas in this subclass, no control of the pre-photocell optical system occurs or, if it does, is not claimed. (3) Note. If a means for indicating the positional information is claimed, then classification is in Class 356, subclasses 139.04 through 139.08, 141.1 through 141.5 and 152.1 through 152.3. (4) Note. The subject matter in this and indented subclasses is differentiated from that in subclasses 231.4+, in that, the latter subclasses deal with rotating shafts which are not considered to be moving targets since their location in global space is fixed even though they are rotating on an axis. Targets, on the other hand, are changing their global position regardless of whether they are spinning about an axis.

206.2	Detection of positional information in two more planes (e.g., azimuth and elevation; hour angle and declination):
	This subclass is indented under subclass 206.1.  Subject matter in which the positional information of a target moving relative to one or more photocells relates to two or more planes, e.g., azimuth and elevation, or hour angle and declination, and may be expressed in any coordinate system, e.g., Cartesian (X,Y,Z) or radial (r, theta).

206.3	With moving reticle in optical path:
	This subclass is indented under subclass 206.2.  Subject matter in which a moving, e.g., rotating or oscillating, apertured or patterned element is in the optical path between the target and photodetector(s) to modulate the light reaching the photodetector(s) from the target. (1) Note. A reticle is often used (a) to chop the light reaching the photodetector(s) to permit amplification of the signal generated by the photodetector(s); (b) to aid in distinguishing the target from background illumination; and (c) to generate signals indicative of the position (e.g., azimuth and elevation) of a target. SEE OR SEARCH THIS CLASS, SUBCLASS: 233, rotary light choppers to modify light reaching a photocell. SEE OR SEARCH CLASS: 359,  Optical: Systems and Elements,   subclasses 234+ for reticles which rotate in an optical path to control light.

207	Electron multiplier:
	This subclass is indented under subclass 206.1.  Subject matter in which the photocell has plural electrodes, one or more of which is photoemissive, and in which secondary emission takes place. (1) Note. Secondary emission is the emission of electrons from a material when bombarded by primary electrons. The secondary emission may take place at the photoelectric cathode or at one or plural other electrodes. SEE OR SEARCH CLASS: 330,  Amplifiers,   subclass 42 for amplifiers having a secondary emissive tube.

208.1	Plural photosensitive image detecting element arrays:
	This subclass is indented under subclass 206.  Subject matter having plural photocells structured in the form of a one or two dimensional array capable of sensing an image of an object viewed by the array. (1) Note. Subject matter in this subclass does not provide for means, e.g., electronic scanning means, coupled to the photosensitive image detecting array to generate a picture image. (2) Note. Subject matter in this subclass includes arrangements of semiconductive photosensitive elements within an array which control an optical or electrical device and, therefore, do not fall within the scope of certain subclasses in Class 257 which are limited to arrays, per se. (3) Note. If plural photocells are used to generate a picture image of an object viewed by the plural photocells, e.g., linear or area photocell arrays, the pictorial signal scanning and generation means will remove the subject matter from this class and subclass and take it to Class 348, subclasses 294+ and 332 and Class 358, Facsimile, subclasses 471+. SEE OR SEARCH THIS CLASS, SUBCLASS: 204, for photocell systems having plural optical paths which terminate at plural photosensitive electrodes and in which the optical paths are controlled by the photosensitive electrodes to balance the light flux in the plural paths. 207, for photocell systems in which the photocell has plural electrodes, some of which act as secondary emitters. SEE OR SEARCH CLASS: 348,  Television,   subclasses 294+ , for solid-state image sensor and subclass 332 for array of photocells for generating visible image of an object. 356,  Optics: Measuring and Testing,   subclass 222 for use of plural photocell photometers; subclass 343, using plural photocells to detect particle light scattering; subclass 411, for use of plural photocells to measure color of flowing liquids by light transmission; and subclass 435 for use of plural photocells to measure light transmission or absorption. 382,  Image Analysis,   subclass 68 , full retina optical image sensing, for arrays of photocells that scan characters for recognition purposes.

208.2	Plural photosensitive nonimage detecting elements:
	This subclass is indented under subclass 206.  Subject matter having plural photocells structured or arranged so that they collectively do not detect or generate a picture image signal of an object from which light is detected by the photocells.

208.3	With electronic scanning:
	This subclass is indented under subclass 208.2.  Subject matter with means to electronically, as distinct from mechanically, scanning of the photocell outputs to obtain an output signal or signals representative of the output signals of the plural photocells.

208.4	Used to switch an electrical circuit or device on or off:
	This subclass is indented under subclass 208.2.  Subject matter in which plural photocells are, by disclosure, used to generate signals which are used to switch all or just part of an electrical circuit on or off. SEE OR SEARCH THIS CLASS, SUBCLASS: 214, for photocell controlled switching circuits, per se. SEE OR SEARCH CLASS: 340,  Communications: Electrical,   subclasses 500+ for condition responsive devices which are responsive to radiant energy and which use photocell controls to turn on alarms or other indicators in response to a specific condition sensed by the photocells. 361,  Electricity: Electrical Systems and Devices,   subclasses 174+ for condition responsive control systems for electromagnetic devices which use a light sensor for controlling its light path.

208.5	With photodetector output ratioing other than by bridge or push-pull circuits:
	This subclass is indented under subclass 208.2.  Subject matter in which circuit means are provided for forming a ratio of the outputs of two or more photodetectors other than by using bridge or push-pull circuits. (1) Note. This subclass provides for many circuits which form ratios digitally rather than by older bridge or push-pull circuits. The latter are classified in Class 250, subclass 210. SEE OR SEARCH THIS CLASS, SUBCLASS: 210, for circuits which form ratios by using bridge or push-pull circuits.

208.6	With specific relative positional geometry of photosensitive elements (e.g., an annular photosensitive element surrounding a coaxially mounted photosensitive element):
	This subclass is indented under subclass 208.2.  Subject matter in which the plural photosensitive elements are arranged in a predetermined, specific geometric orientation relative to each other to provide a desired result, e.g., detecting specularly reflected light as well as diffusely reflected light from an object viewed by the photosensitive elements. SEE OR SEARCH THIS CLASS, SUBCLASS: 227.28, with specific light conductor or conductor component configuration, for related subject matter involving specific relative positional geometry of light conductors or components.

210	Bridge and push-pull circuits:
	This subclass is indented under subclass 206.1.  Subject matter in which the photocell is in a bridge circuit or in a push pull circuit. SEE OR SEARCH THIS CLASS, SUBCLASS: 209, for bridge circuits having plural photocells, plural photosensitive electrodes or plural nonphotosensitive electrodes.

214	Special photocell or electron tube circuits:
	This subclass is indented under subclass 206.  Subject matter including means to electrically connect a particular photocell or electron tube with one or more electrical or electronic devices in a closed or closable electrically conducting path. SEE OR SEARCH THIS CLASS, SUBCLASS: 315, Electric Lamp and Discharge Devices: Systems, subclasses 10+ for photocell circuits in which the photocell controls a cathode-ray tube or in which the photocell is part of a cathode-ray tube, and subclasses 149+ for photocell circuits in which the photocell controls a lamp or gas or vapor discharge device. SEE OR SEARCH CLASS: 330,  Amplifiers,   appropriate subclasses, particularly subclass 59 for light controlled or light activated devices.

214.1	Special photocell:
	This subclass is indented under subclass 214.  Subject matter in which the photocell has characteristics which are sufficiently unique to be stated in the claims. (1) Note. For a compilation of the classes which provide for photocells, per se, see (7) Note to subclass 200 of this class.

215	Combined with diverse-type device:
	This subclass is indented under subclass 200.  Subject matter in which the photocell is built into a device specific to an art other than the photocell art, and in which the utility of the art device is not destroyed by removal of the photocell. (1) Note. As an example, a refrigerator which is provided with a photocell controlled defrosting device, in which the photocell senses excessive frost, is found in this subclass, if within the definition of superior subclass 200, since the photocell is (1) built into the refrigerator which (2) is an art device and which (3) has utility if the photoelectric cell is removed. Generally, the patents in this subclass are cross references, as there are few art devices which are not elsewhere provided for.

216	Optical or pre-photocell system:
	This subclass is indented under subclass 200.  Subject matter having means for illuminating the photoelectric cell. (1) Note. The means for illuminating the photoelectric cell should be significant, and if conventional and claimed by name only, is not found in this and indented subclasses. (2) Note. The means for illuminating the photocell need not be a specific light source, but may be the ambient illumination.

221	Controlled by article, person, or animal:
	This subclass is indented under subclass 216.  Subject matter in which the optical path between the light source and the photocell is directly affected by an object which is movable with respect to, is not part of and is not continuously associated with the photocell device. (1) Note. The ultimate object being sensed must directly affect the light beam, and not indirectly through the medium of a linkage, shutter or other instrumentality. Further, the object must be one which is independent of the photocell apparatus in the sense of being nonintegral with it and having an independent existence of its own, regardless of the existence of the photocell apparatus. (2) Note. Examples of such objects are animate objects such as horses on a race track, human beings entering doors, animals in traps or inanimate objects such as plants being cultivated, work pieces being gauged, paint samples being tested. SEE OR SEARCH THIS CLASS, SUBCLASS: 231, for similar subject matter where the article indirectly affects the photocell. 554, for similar subject matter where the article is a flame and illuminates the photocell.

222.1	Inanimate article:
	This subclass is indented under subclass 221.  Subject matter in which the object is an inanimate article.

222.2	Particle detection:
	This subclass is indented under subclass 222.1.  Subject matter in which the article is a particle. SEE OR SEARCH CLASS: 377,  Electrical Pulse Counters, Pulse Dividers, or Shift Registers: Circuits and Systems,   subclasses 10+ for particle counting.

223	Conveyor or chute:
	This subclass is indented under subclass 222.  Subject matter having means for carrying the inanimate article into or out of or through a location where the article will affect the optical path between the light source and the photocell. (1) Note. The conveyor may stop while the article is being sensed. (2) Note. Examples of conveyors are railroad cars on tracks and gravity operated chutes. SEE OR SEARCH THIS CLASS, SUBCLASS: 559.01+, and 566+, for similar subject where the object is a coded record or a web, strand, strip or sheet which is conveyed to the sensing point. 573, for similar subject matter, where the object is fluent or pulverulent and is conveyed to the sensing point.

224	Article and light ray relatively moved during sensing:
	This subclass is indented under subclass 222.  Subject matter having means for causing relative movement between the inanimate article and the light ray while the article is in the light path between light source and photocell. (1) Note. The motion referred to above is one above and beyond that required to bring the object into the testing or sensing station. During sensing, either the object, light source, photocell or some other part of the optical system may move. (2) Note. As an illustrative example, this subclass includes camera shutter photocell sensing devices, where the camera shutter opens and closes while in the light beam and roller photocell sensing devices, where the roller is rotated while being sensed for size. SEE OR SEARCH THIS CLASS, SUBCLASS: 223, for similar subject matter where the inanimate article is moved through the sensing station by a conveyor. 559.01+, and 566+, for similar subject where the object is a coded record or a web, strand, strip or sheet which is conveyed to the sensing point.

225	Polarizing:
	This subclass is indented under subclass 216.  Subject matter having a polarizer in the optical path between light source and photocell. SEE OR SEARCH CLASS: 359,  Optical: Systems and Elements,   subclasses 483+ for polarizers, per se.

226	Color (e.g., filter or spectroscope):
	This subclass is indented under subclass 216.  Subject matter having optical means for acting unequally upon different frequencies of radiation in the optical path of light from a light source to the photocell. (1) Note. Examples of such optical means, found in this subclass, are diffraction gratings, dispersion prisms and visible light filters. SEE OR SEARCH THIS CLASS, SUBCLASS: 211, for similar subject matter, where the photocell has inherent selective color sensitivity. 239, for photocells which are provided with cooling means to absorb infrared rays. 361+, where the photocell is provided with means to enhance response to invisible radiant energy or diminish response to visible radiant energy, e.g., an ultraviolet filter.

227.11	Light conductor:
	This subclass is indented under subclass 216.  Subject matter including an optical fiber or rod, made of a material having a high index of refraction that allows it to confine, guide and transmit light. SEE OR SEARCH CLASS: 385,  Optical Waveguides,   appropriate subclasses for light conducting elements, per se. 398,  Optical Communications,   particularly subclasses 134 , 141, 178, 200, and 214 for light wave communications systems which employ optical waveguides optically coupled to photocells.

227.12	Optical delay line:
	This subclass is indented under subclass 227.11.  Subject matter where the light conductor is used to decrease the speed of a light pulse directed toward a photodetector. (1) Note. Typically, light pulses are directed through a light conductor in which the speed of light is slower than through air or vacuum. The arrival of a pulse going through the light conductor is delayed from the time it would have arrived had it travelled directly through air or vacuum.

227.13	Light pen:
	This subclass is indented under subclass 227.11.  Subject matter wherein a photocell and light conductor are combined in a single instrument configured to be hand held. SEE OR SEARCH CLASS: 235,  Registers,   subclasses 472.01+ for hand held optical coded record sensors. 345,  Computer Graphics Processing and Selective Visual Display Systems,   subclasses 180+ for visual displays employing light pens. 382,  Image Analysis,   subclass 59 for hand held image sensing means.

227.14	Condition responsive light guide (e.g., light guide is physically affected by parameter sensed which results in light conveyed to the photocell):
	This subclass is indented under subclass 227.11.  Subject matter in which the light which photocell senses is affected by some property of the light conductor itself which is, in turn, acted upon by the condition or parameter being sensed and the photocell generates an electric signal in response thereto. (1) Note. The light conductor itself transduces a quantity or parameter which is sought to be measured quantitatively or qualitatively by the photodetector.

227.15	With detection of macroscopic break in fiber:
	This subclass is indented under subclass 227.14.  Subject matter wherein the detector and a light conducting fiber are positioned, configured or arranged so that light is coupled to or away from a detector if there is a break in the fiber to sense the presence of a break. SEE OR SEARCH CLASS: 340,  Communications: Electrical,   subclasses 600+ for condition responsive devices which detect radiant energy. 356,  Optics: Measuring and Testing,   subclass 73 for testing of the optical properties of fiber optic light guides.

227.16	With detection of fiber microbend caused by parameter affecting fiber:
	This subclass is indented under subclass 227.14.  Subject matter in which a photodetector sense a small scale, i.e., micro, bend in an optical fiber caused by a parameter such as pressure, temperature, stress or strain, etc. SEE OR SEARCH THIS CLASS, SUBCLASS: 231.1+, for photocell control of light valve pre-photocell systems which are activated by external physical quantities. SEE OR SEARCH CLASS: 73,  Measuring and Testing,   subclass 705 , photoelectric fluid pressure gauges; and subclass 800 for optical testing of specimen stress or strain. 356,  Optics: Measuring and Testing,   subclasses 32+ for optical measurement and testing of material strain.

227.17	Causing polarization change in fiber:
	This subclass is indented under subclass 227.14.  Subject matter in which the condition sensed changes the polarization of the light passing through the fiber due to some parameter affecting the fiber so that light of a different polarization reaches the photodetector than was incident on the fiber.

227.18	Causing light spectral frequency/wavelength change:
	This subclass is indented under subclass 227.14.  Subject matter in which the condition sensed causes a change in frequency/wavelength of the light transmitted to the photodetector by the light conductor. (1) Note. The photocell may, for example, detect changes in the frequency of the light transmitted to it by the light conductor due to changes in the elongation of the light conductor. (2) Note. This subclass provides for significant light conductor means in detecting color whereas subclass 226, is directed to color detection broadly. SEE OR SEARCH THIS CLASS, SUBCLASS: 226, color (e.g., filter or spectroscope), for related subject matter that may or may not include light conductors. SEE OR SEARCH CLASS: 209,  Classifying, Separating, and Assorting Solids,   subclasses 580+ , for sorting articles based on their color. 356,  Optics: Measuring and Testing,   subclasses 402+ , measuring and testing color of an object; subclasses 300+ for measuring and testing by dispersed light spectroscopy. 436,  Chemistry: Analytical and Immunological Testing,   subclasses 164+ optical result, including subclass 171, optical spectrum, where the test and the result involves a chemical reaction. 702,  Data Processing: Measuring, Calibrating, or Testing,   appropriate subclasses.

227.19	With coherent interferrometric light:
	This subclass is indented under subclass 227.14.  Subject matter wherein the light waves transmitted by the light conductor are coherent, i.e., the phases of the waves are substantially in step spatially and temporally, and the condition sensed by the light conductor affects the coherent light so that an interferometric pattern is presented to the photocell. (1) Note. This definition is inclusive and includes, for example, arrangements where noninterferometric light is presented to a photocell along with an interferometric pattern to a photocell. (2) Note. This type of device ordinarily includes fiber-optic equivalents of classic interferometers, e.g., Michelson interferometers, and ring laser gyroscopes. It also includes detection of changes in the state of polarization in a light conductor, e.g., induced birefringence by stresses or strains. (3) Note. This is a residual subclass in a residual class and other classes and subclasses, e.g., Class 356, subclasses 32+ or 345+, provide for this subject matter where optical measurement and testing are involved, and take precedence. Cross-references to this subclass (277.19) are discretionary. SEE OR SEARCH THIS CLASS, SUBCLASS: 550, interference pattern analysis for related subject matter which may or may not involve light conductors but which does not claim significant light conductor means. SEE OR SEARCH CLASS: 356,  Optics: Measuring and Testing,   subclass 450 for measuring and testing by light interference involving, inter alia, coherent interferometric light. 359,  Optical: Systems and Elements,   subclasses 1+ provide for holographic systems which employ coherent interferometric light. 365,  Static Information Storage and Retrieval,   subclasses 215+ for optical, including holographic, read/write circuits which may include light conductors handling interferometric light.

227.2	With imaging:
	This subclass is indented under subclass 227.11.  Subject matter wherein the light conductor presents an image of the object viewed by it to the photocell, outputting the elements of the object(s) that it views in the same spatial relationship they have in reality. (1) Note. An imaging light conductor is defined as one which presents an image of the object viewed by it to the photocell(s). An imaging light conductor outputs the elements of the object(s) it views in the same spatial relationship they have in reality. An incoherent light conductor is one which scrambles the object it views so that what is transmitted to the photocell(s) is not an image of the original, but is light reflected by or transmitted through the object in a nonimage form. A coherent light conductor can present a true image of an object it views to a photocell with ordinary incoherent light reflected from or transmitted through the object. SEE OR SEARCH CLASS: 385,  Optical Waveguides,   subclasses 116+ and 133, for imaging light conducting guides/fiber bundles, per se.

227.21	With light chopping or modulation:
	This subclass is indented under subclass 227.11.  Subject matter wherein means are provided for varying the intensity of the light transmitted to the photocell from substantially zero to substantially maximum intensity as a function of time. (1) Note. The chopping or modulating means may be for example, electromechanical or electrooptical, an object under inspection or analysis, or a keyboard controlled optical shutter, for example. SEE OR SEARCH CLASS: 359,  Optical: Systems and Elements,   appropriate subclasses for light modulators/chopping devices, per se, as well as for optical logic devices.

227.22	Keyboard or other manual switch controlled:
	This subclass is indented under subclass 227.21.  Subject matter in which the means to operate the light gate or modulator is a manually operable switch or keyboard. SEE OR SEARCH THIS CLASS, SUBCLASS: 229, for light chopping or modulation type pre-photocell optical systems. SEE OR SEARCH CLASS: 341,  Coded Data Generation or Conversion,   subclass 31 for photocell controlled keyboard coders which include code conversion data processing.

227.23	With spectral frequency/wavelength discrimination:
	This subclass is indented under subclass 227.11.  Subject matter including means for selecting and transmitting light of one or more discrete wavelengths or wavelength bands by the light conductor(s) to the photocell(s). (1) Note. The intensity of the light of different wavelengths may be varied by using, for example, polarizers, diaphragms, etc. (2) Note. This subclass provides for significant light conductor means in detecting color, whereas subclass 226 is directed to color detection broadly. SEE OR SEARCH THIS CLASS, SUBCLASS: 226, color (e.g., filter or spectroscope), for related subject matter that may or may not include light conductors, SEE OR SEARCH CLASS: 209,  Classifying, Separating, and Assorting Solids,   subclasses 580+ for sorting articles based on their color. 356,  Optics: Measuring and Testing,   subclasses 402+ measuring and testing colors of an object, subclasses 300+ for measuring and testing by dispersed light spectroscopy; and subclass 451 measuring and testing by interferometric spectroscopy. 436,  Chemistry: Analytical and Immunological Testing,   subclasses 164+ , optical result, including subclass 171, optical spectrum, where the test and the result involves a chemical reaction. 702,  Data Processing: Measuring, Calibrating, or Testing,   appropriate subclasses.

227.24	With coupling enhancement means:
	This subclass is indented under subclass 227.11.  Subject matter with means used to increase the overall coupling efficiency of the light conductor and the photocell, i.e., to improve the ratio of light reaching the photocell from the light conductor to the light leaving the photoconductor on its way to the photocell. (1) Note. Coupling enhancement means may or may not include structure to physically or mechanically connect a photocell to a light conductor. The enhancement means may, for example, simply include configurations to improve evanescent wave coupling phenomena, or modal coupling phenomena, or may include optomechanical connectors. (2) Note. A light conductor coupled to a photocell may be classified here or in Class 356, subclasses 96+, depending on what is recited. If the photocell is just nominally recited, and the coupling enhancement means is recited nominally or in detail, then classification is proper in Class 385. If the photocell is recited more than nominally, i.e., including an electrical output which is generated for utilization, then classification is in this subclass regardless of the claimed detail of the coupling enhancement means. SEE OR SEARCH CLASS: 385,  Optical Waveguides,   subclasses 15+ for optical coupling means, per se. See Note (2), above.

227.25	Fluid coupling:
	This subclass is indented under subclass 227.24.  Subject matter in which the coupling enhancement means is a fluid, i.e., in the gas or liquid state.

227.26	With scanning:
	This subclass is indented under subclass 227.11.  Subject matter with means to actually or electronically move a light beam transmitted by a light conductor over an object. (1) Note. The scanning may involve a stationary light conductor and moving optical elements such as lenses or reflectors, or may involve moving the light conductor. It also may include electronic scanning of the photocells optically coupled to the light conductors. SEE OR SEARCH CLASS: 348,  Television,   subclasses 197 and 359 for television scanners employing fiber optics. 359,  Optical: Systems and Elements,   subclasses 196.1 through 226.3,227+, 240+, 290+, and 298+ for various optical scanning means.

227.27	With coherent interferrometric light:
	This subclass is indented under subclass 227.11.  Subject matter wherein the light waves transmitted by the light conductor are coherent, i.e., the phases of the waves are substantially in step spatially and temporarily, and the condition being sensed by the light conductor affects the coherent light to present an interferometric pattern to the photocell. (1) Note. This definition is inclusive and includes arrangements where noninterferometric light is presented to a photocell along with presentation of an interferometric pattern to a photocell. (2) Note. This type of device ordinarily includes use of light conductors which transmit light with a spatial energy distribution which is characterized as a single transverse electromagnetic mode (TEM) distribution. Included are not only single interferometric devices, but optically coupled (by light conductors) multiple interferometric devices. SEE OR SEARCH THIS CLASS, SUBCLASS: 550, interference pattern analysis for related subject matter which may or may not involve light conductors but which does not claim significant light conductor means. SEE OR SEARCH CLASS: 356,  Optics: Measuring and Testing,   subclass 450 for measuring and testing by light interference involving, inter alia, coherent interferometric light. 365,  Static Information Storage and Retrieval,   subclasses 215+ for optical, including holographic, read\write circuits which may include light conductors handling interferometric light.

227.28	With specific configuration of light conductor components with respect to each other:
	This subclass is indented under subclass 227.11.  Subject matter in which the components of a light conductor have a specific, predetermined configuration with respect to each other to achieve a desired light beam pattern to be presented to the photodetector means, e.g., one with suppressed higher order transverse electromagnetic (TEM) modes. SEE OR SEARCH CLASS: 385,  Optical Waveguides,   appropriate subclasses for optical fibers with specific components, per se.

227.29	With specific illumination or viewing orientation of light conductor relative to viewed object (e.g., light normal to, and detector at 45 degree angle to, viewed object):
	This subclass is indented under subclass 227.11.  Subject matter in which the angular relationship of the light source, photodetector means and object being illuminated and detected have a specified geometric relationship. (1) Note. For example, the photodetector may be placed at 45 degrees to the normal of the illuminated surface, while the optical axis of the light source may be placed perpendicular to the object surface.

227.3	With variable orientation of light conductor relative to viewed object (e.g., goniometer):
	This subclass is indented under subclass 227.11.  Subject matter in which means are provided to vary the angular relationship of the light source or photodetector with respect to the surface of the object under illumination and photodetection. (1) Note. Devices with means to vary the angular relationship between light source, object surface and photodetector are conventionally known as goniometers. SEE OR SEARCH CLASS: 356,  Optics: Measuring and Testing,   subclass 340 , measuring particle light scattering with photocell detection at variable angle to the light beam.

227.31	Side or edge illuminated light conductor or collector:
	This subclass is indented under subclass 227.11.  Subject matter in which the light conductor is configured or arranged to receive light along its side or edge in lieu of, or in addition to, its end face. (1) Note. Typical examples include solar collector light collecting guides and optical scanning light conductors.

227.32	End illuminated light conductor with noncircular geometric cross section:
	This subclass is indented under subclass 227.11.  Subject matter wherein the light conductor has a noncircular end-face configuration which is end-face illuminated. (1) Note. The light conductors in this subclass are end-face illuminated whereas in the previous subclass they are illuminated along their side or edge faces. Both subclasses encompass light conductors of various geometries other than cylindrical or circular.

228	Integrating sphere:
	This subclass is indented under subclass 216.  Subject matter having an integrating sphere in the optical path between light source and photocell. (1) Note. An integrating sphere is a hollow body having an interior of highly light reflecting but also diffusing material, and having relatively small openings in the shell of the hollow body to admit light. It has the property of raising the interior illumination to a level which depends only upon the amount of light flux entering the openings and not upon the reflection or diffusion of that incident light flux.

229	Light valve (e.g., iris diaphragm):
	This subclass is indented under subclass 216.  Subject matter having means in the optical path between light source and photocell for varying the amount of light which reaches the photocell. (1) Note. In this subclass, the means for varying the amount of light which reaches the photocell is always a part of, or is continuously associated with, the photocell device, and is not an object which has an independent existence of its own. Devices found in this and indented subclass comprises, for example, keyboard operated shutters which variably permit a light source to illuminate a photocell, iris diaphragms and optical wedges. SEE OR SEARCH THIS CLASS, SUBCLASS: 221+, for similar subject matter in which the light path between light source and photocell is directly affected by an object which is not part of the photocell apparatus and has an independent existence of its own. 237, for similar subject matter comprising relatively stationary hoods, gratings, baffles or diaphragms.

230	Reflection type (e.g., mirror galvanometer):
	This subclass is indented under subclass 229.  Subject matter in which the optical path between light source and photoelectric cell includes a reflective element, and in which the amount of reflection or the direction of reflection is varied so as to vary the intensity of the photocell illumination. (1) Note. Examples of such variable reflecting elements include mirrors which oscillate under the control of a physical quantity and compass cards which have variable reflective markings.

231.1	Actuated by dynamic external physical quantity:
	This subclass is indented under subclass 229.  Subject matter in which the means in the optical path between the light source and the photocell for varying the amount of light which reaches the photocell is actuated by an external mechanical force. (1) Note. Examples of dynamic type physical quantities include pressure, weight (mg where m = mass of an object andg = gravitational force), force (f) where f = ma or f = 1/2 mv squared), deflection of an object connected to the means in the optical path for varying the amount of light reaching the photocell, speed of an object, velocity of an object (including fluid flow), position (angular or linear) of an object. (2) Note. Measurement of the position of an object properly classified herein is distinct from the position indication classified in this class, subclasses 206.1+ in that the latter concerns global position of a target whereas this subclass concerns local position, e.g., rotation of a shaft about an axis where the shaft"s global position is known or not of concern. (3) Note. Excluded from the definition of dynamic type physical quantities are electrical quantities, e.g., current, voltage, impedance; chemical properties; passive physical quantities and forces, such as color, temperature, physical dimensions (length, width, diameter, Coriolis force); and quantum mechanical forces and properties. SEE OR SEARCH CLASS: 33,  Geometrical Instruments,   subclass 363 , for electrical telemetering with a photoelectric pickoff; and subclass 707 for distance measuring including optical means. 73,  Measuring and Testing,   subclass 290 for measuring and testing involving, inter alia, radiant energy detection; and subclass 705 for photoelectric fluid projection gauges. 324,  Electricity: Measuring and Testing,   subclasses 96+ for measurement, testing or sensing of electricity using radiant energy; and subclass 344, for use of a radiant energy receiver for a geological measurement or test. 356,  Optics: Measuring and Testing,   for measurement of passive physical forces such as color ( subclasses 402+ ); temperature (subclasses 43+), and physical dimensions (subclasses 2, 3+, 27+, 450, 123, 124+, 372+, 388+, 247+, etc.) 374,  Thermal Measuring and Testing,   subclasses 32 , 121+, and 162 for various temperature measuring means or methods. 396,  Photography,   subclasses 106+ for automatic camera focussing using active ranging. 434,  Education and Demonstration,   subclasses 1+ for electromagnetic sensors to detect or determine the range of an object; subclass 187 for measurement of length or volume; and subclass 303, for science, physics or optics. 435,  Chemistry: Molecular Biology and Microbiology,   subclass 808 for optical sensing apparatus. 436,  Chemistry: Analytical and Immunological Testing,   subclasses 164+ for analytical chemical testing by optical means and involving a chemical reaction. 702,  Data Processing: Measuring, Calibrating, or Testing,   appropriate subclasses.

231.11	Actuated by gauge element deflection:
	This subclass is indented under subclass 231.1.  Subject matter wherein displacement of a gauge component, e.g., needle, by a force, e.g., gravity or an electromotive force is the active external physical quantity sensed.

231.12	Gyroscopes:
	This subclass is indented under subclass 231.1.  Subject matter wherein gyroscopic movements or conditions are the active external physical quantities sensed. SEE OR SEARCH CLASS: 74,  Machine Element or Mechanism,   subclass 5.6 , for gyroscopes with optical pickoffs.

231.13	Shaft angle transducers:
	This subclass is indented under subclass 231.1.  Subject matter wherein the angular position or speed or a rotatable shaft is the active external physical quantity sensed by one or more photocells and an output is generated which is indicative of those parameters. SEE OR SEARCH CLASS: 341,  Coded Data Generation or Conversion,   subclasses 1+ for related subject matter further specifying the coded data generation or conversion circuitry, especially subclasses 13+ and 31 for optical type code converters, including keyboard actuation.

231.14	Incremental shaft readers; i.e., with means to generate increments of angular shaft rotation:
	This subclass is indented under subclass 231.13.  Subject matter wherein photocell means is provided to incrementally sense the angular position or speed of a rotatable shaft as the active external physical quantity and for generating an output proportional to the number of increments sensed by the photocell(s). SEE OR SEARCH CLASS: 341,  Coded Data Generation or Conversion,   subclass 11 for similar subject matter combined with digital signal processing circuitry.

231.15	With plural gear driven discs:
	This subclass is indented under subclass 231.14.  Subject matter in which the incremental data is generated using more than one circularly shaped element coupled to the rotating shaft by gear drive means. SEE OR SEARCH CLASS: 341,  Coded Data Generation or Conversion,   subclass 2 for similar subject matter combined with digital signal processing circuitry.

231.16	Using phase difference of output signals from plural photodetectors:
	This subclass is indented under subclass 231.14.  Subject matter in which a signal proportional to the phase sum of, or difference between, outputs of the photodetectors is generated and is representative of the angular position or speed of the rotating shaft. SEE OR SEARCH CLASS: 341,  Coded Data Generation or Conversion,   subclass 6 for similar subject matter combined with digital data processing circuitry.

231.17	With means to indicate a complete shaft rotation:
	This subclass is indented under subclass 231.14.  Subject matter in which means are provided to determine whether a complete revolution of the shaft has occurred and to generate a signal representative of that fact. (1) Note. The provision of means to determine the number of complete revolutions is also included in this subclass.

231.18	Position indicating shaft encoders with means to generate a unique signal for each specific angular shaft position:
	This subclass is indented under subclass 231.14.  Subject matter including means to establish a unique number of shaft angle positions and to generate a unique, distinct signal for each of those positions. SEE OR SEARCH CLASS: 341,  Coded Data Generation or Conversion,   subclass 13 for similar subject matter combined with digital signal processing circuitry.

231.19	Pressure-responsive light valves:
	Subject matter under 231.1 wherein the dynamic external mechanical force sensed is pressure ((P) = F/A where F = a Newtonian type force and A = Area over which the force is applied) applied to the means in the optical path for varying the amount of light to reach the photocell(s). SEE OR SEARCH CLASS: 73,  Measuring and Testing,   subclass 705 for photoelectric fluid pressure gauges.

232	Light chopper type:
	This subclass is indented under subclass 229.  Subject matter having means for intermittently interrupting the optical path between the light source and photocell in a repetitious cyclic sequence. (1) Note. A camera shutter is generally not a light chopper, of the type found in this class, since it opens and closes in a nonrepetitious, noncyclic manner.

233	Rotary:
	This subclass is indented under subclass 232.  Subject matter in which the means for intermittently interrupting the optical path is a rotary element.

234	Means for moving optical system:
	This subclass is indented under subclass 216.  Subject matter having means for moving an element of the optical system. (1) Note. Examples of such means are means for adjusting the photocell so that its axis is aligned with the optical axis, a hand crank for adjusting the photocell to sense in a desired direction or a vehicle upon which the entire photocell apparatus is mounted. SEE OR SEARCH THIS CLASS, SUBCLASS: 218, for photocell sensing means in which a fluent material is moved through the optical path between light source and photocell. 223, and 224, for photocell sensing means in which an inanimate object is moved to or from or while in the optical path. 229+, for photocell sensing means having a light valve in the optical path, particularly indented subclass 231, where the light valve is adjusted in accordance with an external physical quantity and subclasses 232+, where the light valve continuously moves to chop the light. 559.01+, and 566+, for similar subject where the object is a coded record or a web, strand, strip or sheet which is conveyed to the sensing point.

235	Repetitious path:
	This subclass is indented under subclass 234.  Subject matter having means for cyclically moving an element of the optical system in a repetitious path. (1) Note. This subclass includes photocell devices having a vibratory scanner. An adjusting means is not deemed a means for providing a repetitious path, since there is no means for ensuring repetition or cycling. A hunting device which follows another element does not cycle, even though the followed element may, during its motion, fortuitously cycle.

236	Rotary motion:
	This subclass is indented under subclass 235.  Subject matter in which the element of the optical system, which moves in a cyclic path, rotates. SEE OR SEARCH CLASS: 348,  Television,   subclasses 199+ , 202, and 203+ for Nipkow discs and rotating mirrors.

237	Hoods, grating, baffles, diaphragms, masks:
	This subclass is indented under subclass 216.  Subject matter having a hood, grating, baffle, diaphragm or mask associated with the optical path between light source and photocell. SEE OR SEARCH THIS CLASS, SUBCLASS: 229+, for similar subject matter where the means associated with the optical path between light source and photocell are ajdustable.

238	Temperature control of photocell:
	This subclass is indented under subclass 200.  Subject matter having means for controlling the temperature of the photocell apparatus. (1) Note. If the temperature of nonphotocell apparatus is controlled, search should not be made here, but rather in the nonphotocell art concerned.

239	Housings (in addition to cell casing):
	This subclass is indented under subclass 200.  Subject matter having a housing for the photocell apparatus.

250	RADIO AND MICROWAVE ABSORPTION WAVEMETERS:
	This subclass is indented under the class definition.  Subject matter which includes sensing means responsive to electromagnetic radiation including a variable electrical member or variable radiation control member having a pointer and an associated scale calibrated in frequency or wavelength units and indicating means responsive to the sensing means to note the maximum energy detected by the sensing means whereby the scale and pointer indicate the wavelength or frequency of the radiation detected.

251	ELECTRICALLY NEUTRAL MOLECULAR OR ATOMIC BEAM DEVICES AND METHODS:
	This subclass is indented under the class definition.  Subject matter comprising means for producing or utilizing a unidirectional stream of molecules or atoms having no net electrical charge, usually through a vacuum with thermal velocity and methods using such means. Such devices and methods may include magnetic field means to deflect, divert or select a portion of the beam of a desired energy level and may also provide means for subjecting the selected portion of the beam to a microwave electromagnetic field to excite the molecules or atoms of the beam at a resonant frequency, causing a transition of the energy state of the molecules or atoms from one energy-level to another. SEE OR SEARCH THIS CLASS, SUBCLASS: 281, for means for effecting the ionic separation or analysis of materials, (e.g., mass spectrometry). SEE OR SEARCH CLASS: 122,  Liquid Heaters and Vaporizers,   for metal and apparatus to heat and vaporize a material by nonelectric means. 219,  Electric Heating,   subclasses 271+ for electric heating of solids and liquids to vaporize the material where no structure to use the vapor is claimed. 239,  Fluid Sprinkling, Spraying, and Diffusing,   particularly subclasses 79+ for apparatus including means to melt particles or bodies of normally solid substance and contiguous means to project the melted substance through the ambient air. 313,  Electric Lamp and Discharge Devices,   subclasses 231.01+ for space discharge devices with fluent material supply or directing means. 314,  Electric Lamp and Discharge Devices: Consumable Electrodes,   subclass 22 for consumable electrode discharge devices which have means to feed a fluent material, (e.g., solid particles) to the discharge space. 315,  Electric Lamp and Discharge Devices: Systems,   especially subclass 111.01 for systems wherein a fluent material is supplied to the discharge area between the discharge electrodes of the discharge device. 324,  Electricity: Measuring and Testing,   subclasses 332+ for measuring or testing devices for utilizing or determining molecular particle resonant properties of substances. 330,  Amplifiers,   particularly subclasses 4+ for maser type amplifying devices that may utilize molecular or atomic beams. 331,  Oscillators,   particularly subclass 3 for oscillators with automatic frequency stabilization utilizing molecular resonant means. 372,  Coherent Light Generators,   appropriate subclasses for molecular or particle resonant type oscillators, (e.g. masers, lasers), which oscillators may utilize molecular or atomic beams. 376,  Induced Nuclear Reactions: Processes, Systems, and Elements,   appropriate subclasses for apparatus or process for effecting a reaction within the nucleus of an element utilizing, for example, subatomic particles, such as thermal neutrons.

252.1	CALIBRATION OR STANDARDIZATION METHODS:
	This subclass is indented under the class definition.  Subject matter which includes methods to establish a reference indication of invisible radiation or invisible radiation level, or methods of error determination or correction using a reference indication or radiation level. (1) Note. For calibration or standardizing apparatus, see the appropriate subclasses for the specific structure involved. SEE OR SEARCH CLASS: 378,  X-Ray or Gamma Ray Systems or Devices,   subclass 207 for testing or calibration of X-ray devices.

253	GEOLOGICAL TESTING OR IRRADIATION:
	This subclass is indented under the class definition.  Subject matter s which includes means in combination with material within or on the surface of the earth to, (1) expose the material to radiation, (2) to detect radiation emanating naturally from the material or (3) to detect radiation modified or caused by the material interacting with radiation produced by the means to expose the material to radiation, and methods therefor. (1) Note. The material within or on the surface of the earth includes the surface of, underneath the surface of or the bottom of a naturally occurring body of water. (2) Note. The irradiation of material includes material within or about a well. SEE OR SEARCH CLASS: 73,  Measuring and Testing,   subclasses 152.01+ for measuring a characteristic of a borehole, a borehole casing, or a drill rigging wherein the measuring is not purely electrical or purely magnetic. 181,  Acoustics,   subclass .5 for geophysical exploration by use of seismic waves. 324,  Electricity: Measuring and Testing,   subclasses 323+ for geophysical surface and subsurface examination using electrical tests and electromagnetic waves below the infrared frequency band in the electromagnetic spectrum. 367,  Communications, Electrical: Acoustic Wave Systems and Devices,   subclasses 14+ for seismic prospecting using electrical acoustic wave systems. 436,  Chemistry: Analytical and Immunological Testing,   subclasses 25+ for methods of prospecting using chemical analysis.

254	With drill or drilling:
	This subclass is indented under subclass 253.  Subject matter which includes apparatus to bore a well and includes methods corresponding to the apparatus. SEE OR SEARCH CLASS: 166,  Wells,   subclass 247 for processes of treating wells using nuclear energy or radioactivity; subclasses 250+ for processes including wells, in combination with indicating, testing or measuring and subclass 66 for apparatus in combination with a well for giving electrical signals concerning something in relation to the well. See also section VI of the general notes to Class 166. 175,  Boring or Penetrating the Earth,   particularly subclass 41 for the combination of boring or drilling with a radiant energy test. See subclass 40, (3) Note for the line between Class 250 and Class 175.

255	With sampling:
	This subclass is indented under subclass 253.  Subject matter which additionally includes means to remove a portion of the material from the earth whereby the portion is subjected to (1) the means to detect natural radiation or (2) radiation modified or caused by the portion when irradiated by means to expose or (3) some other test. (1) Note. The subject matter of this subclass includes sampling on the surface of the earth within a well or at the bottom of a naturally occurring body of water. SEE OR SEARCH THIS CLASS, SUBCLASS: 304, for methods of preparing or separating material for an invisible radiation test or controlling the material during the test. SEE OR SEARCH CLASS: 73,  Measuring and Testing,   subclass 152.07 for borehole formation logging with analysis of density, porosity, or water saturation using core sample analysis, subclass 152.09 for oil, gas, or water saturation by core sample analysis, and subclass 152.11 for other analysis using core sampling. 436,  Chemistry: Analytical and Immunological Testing,   subclasses 25+ for geochemical exploration.

256	Well testing apparatus and methods:
	This subclass is indented under subclass 253.  Subject matter wherein the means to detect radiation emanating naturally from or modified or caused by the material interacting with radiation senses the material in or about a well and includes means to support for movement the means to detect natural radiation or radiation modified or caused by the interaction of the material with exposing radiation and includes methods corresponding to the apparatus. (1) Note. A well is meant to include a cased and uncased well and bore hole. (2) Note. Generally the claimed method and apparatus include an indication or a recording of the radiation detected. (3) Note. Generally the method and apparatus have claimed or disclosed a recording correlating the radiation sensed with the depth at which the radiation has been sensed. SEE OR SEARCH CLASS: 73,  Measuring and Testing,   subclasses 152.01+ for physical analysis of wells particularly subclasses 152.02+, for the identification of strata in a well by physical methods or apparatus. 166,  Wells,   subclasses 250+ , for well processes involving indicating, testing or measuring in combination with a well and subclasses 64 and 66+, for measuring or electrical means combined with a well. 175,  Boring or Penetrating the Earth,   subclass 41 for ray energy detection or measuring apparatus combined with drilling apparatus and subclasses 57+ for processes of boring or penetrating the earth. 181,  Acoustics,   subclass .5 for well exploration by use of seismic waves. 324,  Electricity: Measuring and Testing,   subclasses 323+ for well exploration by electrical, magnetic and radio waves. 340,  Communications: Electrical,   subclasses 853.1+ for telemetering a well. 346,  Recorders,   subclass 33 for a recorder used in a well logging operation.

257	With casing collar detection:
	This subclass is indented under subclass 256.  Subject matter which additionally includes apparatus which includes a detector to sense the location of a pipe collar in a cased well and methods corresponding to the apparatus. (1) Note. The collar detector need not be a radiation detector but can be any type which senses the position of the pipe collar in a well. SEE OR SEARCH CLASS: 73,  Measuring and Testing,   subclass 152.57 for a determination of a characteristic of a borehole casing wherein the determination is made by making a measurement which is not purely electrical or purely magnetic.

258	By interface of fluids:
	This subclass is indented under subclass 256.  Subject matter which includes means to cause two fluids to meet in a well to force one of the fluids into the earth, said one fluid being material or including material which emanates radiation, modified radiation, or causes radiation by interacting with radiation from the means to expose the material to radiation, wherein the means to detect radiation senses the said one fluid at the meeting point of the fluids, and methods corresponding to the apparatus. (1) Note. Generally, the depth at which the meeting point of the fluids occurs is recorded along with the results of the sensing. SEE OR SEARCH THIS CLASS, SUBCLASS: 259+, for fluids added to a well which may be or contain tracer material which is fluorescent or radioactive or capable of being made radioactive by irradiation.

259	With placement of tracer in or about well:
	This subclass is indented under subclass 256.  Subject matter which includes means to add the material into the well or the earth about the well whereby the means to detect senses the radiation emitted naturally from the material, or radiation caused by or modified by the material interacting with the radiation produced by the means to expose the materials to radiation. (1) Note. The material may be solid liquid, gas, particulate or entrained within a fluid. (2) Note. The means to eject the tracer material into a well is included here as a subcombination not classified elsewhere. (3) Note. Materials which are not radioactive, but are made radioactive in the well are placed here along with materials which can control radiation in some manner. SEE OR SEARCH THIS CLASS, SUBCLASS: 302+, for methods detecting tracer materials which emit or modify radiation generally.

260	Tracer being or including radioactive material:
	This subclass is indented under subclass 259.  Subject matter wherein the added material is radioactive or contains radioactive material entrained in a substance added to the well. SEE OR SEARCH THIS CLASS, SUBCLASS: 259, for tracers which must be irradiated in the well before they become radioactive. 303, for methods detecting radioactive tracers generally. 493.1+, for radioactive sources which are more than a composition, recited as a source. SEE OR SEARCH CLASS: 252,  Compositions,   subclass 301.1 for radioactive compositions. 424,  Drug, Bio-Affecting and Body Treating Compositions,   subclass 1 for a radioactive composition for medical use. 600,  Surgery,   subclasses 1+ for radioactive substances applied to the body for therapeutic purposes and holders therefore.

261	With detector or detector circuit control:
	This subclass is indented under subclass 256.  Subject matter wherein the means to detect radiation emanating naturally or radiation modified or caused by the material interacting with the radiation includes a detector and may include an electrical circuit responsive to the detector and apparatus to control or compensate for some physical or electrical condition of the radiation detector circuit or detector and circuit and includes methods corresponding to the apparatus. (1) Note. The conditions controlled include temperature control, voltage control of the detector or circuit and the speed of the detector while sensing in the well. SEE OR SEARCH CLASS: 62,  Refrigeration,   subclass 260 for temperature control in a geographic location such as a well.

262	With particular detector signal circuit:
	This subclass is indented under subclass 256.  Subject matter wherein the means to detect radiation emitted naturally or radiation modified or caused by material interacting with radiation includes a radiation detector and a detailed electrical circuit connected between the detector and an indicator or recorder of the radiation sensed by the detector and includes methods corresponding to the apparatus.

263	With detector signal modulation or carrier wave:
	This subclass is indented under subclass 262.  Subject matter wherein the electrical circuit includes means to modulate an electrical wave with signals emitted by the detector upon detecting radiation and includes methods corresponding to the apparatus.

264	Having plural detectors:
	This subclass is indented under subclass 262.  Subject matter wherein there are plural detectors and the individual detectors may be connected to the same electrical circuit or to separate electrical circuits and includes methods corresponding to the apparatus. (1) Note. Included are plural detectors connected to an anti-coincidence or coincident circuit. SEE OR SEARCH THIS CLASS, SUBCLASS: 265+, for well-logging circuits having plural detectors where no novelty is in the electrical circuit.

265	Plural detectors:
	This subclass is indented under subclass 256.  Subject matter wherein the means to detect radiation emitted naturally or radiation modified or caused by material interacting with radiation includes plural radiation detectors and methods corresponding to the apparatus. (1) Note. The detectors here may be electrical, nonelectrical, but a combination of a fluorescent screen and a responsive detector is considered but one detector. SEE OR SEARCH THIS CLASS, SUBCLASS: 264, for well testing apparatus using plural radiation detectors wherein the novelty resides in the electrical circuitry between the detectors and a recorder or indicator.

266	With spacing or direction of detectors:
	This subclass is indented under subclass 265.  Subject matter which may include the means to expose the material to radiation which includes at least a radiation source and wherein there are details concerning the location or spacing of the detectors with respect to the source or to one another or the direction the radiation is permitted to be incident upon the detectors and includes methods corresponding to the apparatus.

267	With radiation control to detector:
	This subclass is indented under subclass 256.  Subject matter wherein the means to detect radiation emanating naturally or radiation modified or caused by the material interacting with the radiation includes a detector and includes radiation modifying means to control the radiation incident upon the detector and methods corresponding to the apparatus. (1) Note. The control of the radiation to the detector includes type of radiation, the intensity of radiation, the direction of the radiation hitting the detector, the frequencies of the radiation, the radiation pattern arriving at the detector or the spacing of the detector with respect to source. SEE OR SEARCH THIS CLASS, SUBCLASS: 266, for radiation logging apparatus having plural detectors wherein the spacing of the detectors to each other or to a source or the direction if the radiation reaching the detector is claimed. 505.1+, for radiation controlling attenuators directional elements, filters, shutters, cones, apertures and shields.

268	With well-engaging means:
	This subclass is indented under subclass 256.  Subject matter which includes means to touch the wall of the well, the means to support for movement suspending the means to touch the well and the means to detect radiation as a common unit within the well and methods corresponding to the apparatus. SEE OR SEARCH CLASS: 33,  Geometrical Instruments,   subclasses 783+ for opposed contact type measuring instruments. 73,  Measuring and Testing,   subclass 152.17 for a formation logging device combined with detail of a borehole wall engaging means wherein the logging is made by making a measurement which is not purely electrical or purely magnetic.

269.1	With source and detector:
	This subclass is indented under subclass 256.  Subject matter in which means to expose the material to radiation in or about the well is also supported by the means to support for movement the means to detect radiation, and includes methods corresponding to the apparatus.

269.2	With plural types of detectors:
	This subclass is indented under subclass 269.1.  Subject matter wherein the means to detect radiation includes more than one different type of detector (e.g., a gamma detector and a neutron detector).

269.3	Having gamma source and gamma detector:
	This subclass is indented under subclass 269.1.  Subject matter wherein the means to expose the material to radiation includes a gamma ray source and the means to detect radiation modified or caused by the material includes a gamma ray detector and includes methods corresponding to the apparatus. SEE OR SEARCH CLASS: 376,  Induced Nuclear Reactions: Processes, Systems, and Elements,   subclass 157 for gamma ray activation analysis. 378,  X-Ray or Gamma Ray Systems or Devices,   subclass 88 for gamma ray composition analysis.