A. This class includes methods and apparatus (1) for analyzing light to measure or test its characteristics, such as intensity, color and polarization; (2) for determining the optical or nonoptical properties of materials or articles by noting, as by inspection, measurement, or test the effect produced by the materials or articles on light associated therewith; and (3) for measuring the dimensions of structures or the spatial relationships such as distances or angle bearings of spaced points by comparison of the respective properties (usually direction or spatial position) of the light from these points or by comparison of the properties of these lights with some scale or standard. The light analyzing includes or is for spectroscopy, interference, polarization, beam direction or pattern, focal position of a light source,
shade or color, and photometers. The material or article properties determined are or involve crystal or gem examination, material strain analysis, blood analysis, optical pyrometers, egg candling, cutting blade sharpness, oil testing, document verification, flatness, lens or reflector testing, refraction testing, monitoring moving webs or fabrics, light transmission or absorption, light reflection, inspection for flaws or imperfections in materials, and thread counting.
The dimensioning and spatial relationship determination includes triangulation by a light beam, contour plotting, range or height finders, motion stopping, velocity or velocity/height measuring, sighting where the optical element or reticle moves with the sighted object, particle size determination, particle light scattering, electrophoresis, angle measuring or axial alignment, mensuration or configuration comparison, alignment in a lateral direction, and fiducial instruments.
B. Included also are apparatus and methods to facilitate the viewing of structure as for flaws and imperfections. The structure is usually optically significant such as transparent sheets or bottles or semi-transparent cloth; or the structure is inaccessible as a bore requiring a bore scope. Included also are methods and structure for preparing the sample for an optical test, and optical test standards.
C. Included also are apparatus and methods involving a plurality of measurements or tests each within the scope of this class; and also included are a measurement or test within the scope of this class together with a measurement or test or other art structure provided, per se, elsewhere, but where no provision for the combination is made elsewhere.

LINES WITH OTHER CLASSES AND WITHIN THIS CLASS
A. OPTICAL MEASURING OR TESTING CLASSIFIED ELSEWHERE
Class 33 provides for optical measurements of the light ray type within the scope of this class. See "Geometrical Instruments in This Class and in Class 33," section C, below, for the subject matter placed in Class 33 and Class 356. Class 73 includes optical measuring and testing within the scope of its subclasses. See "Measuring and Testing in This Class and Class 73," section D, below, for the line between Class 73 and Class 356. Signal and indicating apparatus which may involve optics are classified elsewhere. See, for example, temperature, radiant energy, smoke, or gas indicators. Surgical diagnostic instruments which may involve optical measuring or testing on or in the body are elsewhere. Television systems for measuring and testing which may include optical elements are classified elsewhere. Photocells and associated circuitry together with optical structure which may involve measuring or testing are classified elsewhere. However, this Class 356 includes optical testing with a photoelectric light detector and
usually claiming either an indicator or structure to support or contain the specimen or sample under test. Lamp and discharge device testing is classified elsewhere. Eye examining and testing instruments which may include optical measuring or testing are elsewhere. (See Subclass References to the Current Class and References to Other Classes, below, for subclass references of subject matter above.)
B. TESTING AND MEASURING SUBCOMBINATIONS PROVIDED FOR ELSEWHERE
Optical elements which may be used in measuring and testing apparatus are classified elsewhere as are the conventional optical elements such as lenses, prisms, and mirrors. Subclasses relating to scale or indicia reading should be particularly noted. Photocell circuits and apparatus are elsewhere. Photo-sensitive discharge devices are classified elsewhere. Mechanical scales and gauges which may be part of optical measuring systems are elsewhere. Mechanical indicators which may be part of optical measuring systems classified elsewhere. Electrical indicating and measuring devices which may be part of optical measuring systems are classified elsewhere. (See References to Other Classes, below, for class/subclass references to these art areas.)
(1) Note. Telemetric signaling means useful in transmitting a measured quantity, not limited to any particular measuring instrument provided for in other classes, is classified elsewhere, while Class 356 takes such telemetric signaling means in combination with a particular measuring means of the type provided for in Class 356. (See References to Other Classes, below.)
C. GEOMETRICAL INSTRUMENTS IN THIS CLASS AND IN CLASS 33
This Class (356) provides for measuring devices which are used for determining spatial relationships, and which involve the establishment of an optical axis between the observer's station and a remote point and which include significant optical structure. This includes certain types of range-finders, angle or azimuth measuring instruments and velocity measuring devices as qualified below. In this subject matter the recitation of specific optical details such as lens, prism, or mirror details is sufficient for classification in this Class 356. Exceptions which remain in Class 33 are bomb sights with specific optical line sighting instruments with a telescope or microscope recited even in some detail, and as a viewing aid to but not a part of the sighting instrument. Also where a plurality of optical functions are recited as, for example, plural reflections of a line of sight, classification is in this Class 356. Where optic is only recited broadly as, for example, "an optical axis", a "telescope", or a "deflection of the line of sight", the subject matter is generally classified in Class 33, as opposed to Class 356.
Also included in this Class 356 are instruments for visual
sighting which in addition to having a field of view, perform an aiming or alignment function or establish a line of sight by means of an artificial reference and which include significant optical structure.
The geometrical instruments of this Class 356 usually either involve the determination of the direction of a point remote from an observer with respect to some reference direction where the two directions may be viewed and compared simultaneously; or the determination of the relative direction of two points remote from an observer where the two directions may be viewed and compared simultaneously. Optical structure is usually provided to facilitate this simultaneous viewing. The subject matter of Class 33 relates more to the direction determination by aiming an instrument on a point and later noting the direction of the aimed instrument with respect to some reference such as a level, compass, or other point. A mere single deflection of a line of sight as by a mirror or lens to facilitate the viewing is not precluded from Class 33. In the mensuration or figure comparison, the patents in this Class 356 include structure to facilitate the viewing (usually simultaneously) of the specimens, or configurations to be compared with other specimens or configurations or with scales, masters, or patterns.
A single sight line optical instrument such as a transit with structure for indicating the direction is classified in Class 33. However where such an instrument includes a sighting mark or scale at an optically critical position such as in the focal plane classification is in Class 356.
Comparison instruments which merge the rays from diverse directions for common viewing as in a split image range finder are classified in Class 356. However plural sighting instruments which merely aim on angularly separated points (even simultaneously) with mechanical reading of the directions are classified in Class 33. Space measuring instruments whose operation is essentially optical such as optical interferometers are classified in Class 356 as opposed to Class 33. Reticles and cross hairs generally are classified in Class 33. However, optical reticles which reflect or refract light are classified in Class 356.
D. MEASURING AND TESTING IN THIS CLASS AND CLASS 73
This Class (356) provides for optical measuring and testing as defined above. Class 73 provides for measuring and testing which may include optical measuring and testing as defined, combined with some nonoptical limitations beyond the scope of this Class 356 and specifically provided for in Class 73. Specific provision exists in Class 73 when the measurement or test is of the type provided for by the subclasses of Class 73 definitions. For example, Class 73 provides for gas chromatography involving color determination of the Class 356 type together with some manipulation of the gas beyond the scope of Class 356. Again Class 73 provides
for engine testing involving optical tests of the Class 356 type together with some mechanical manipulation of the parts beyond the scope of Class 356. In general Class 73 provides for measuring and testing of the type indicated by its subclass titles and definitions which may include optical steps together with other mechanical measuring and testing steps beyond the scope of Class 356. There are some patents presently in Class 73 which relate to measuring and testing as there provided, but which claim only optical subject matter within the scope of Class 356. Combinations of optical measuring or testing with other structure or methods is classified in Class 356 if no provision for such combinations exists elsewhere. (See References to Other Classes, below.)
An exception to the above involves cutting blade sharpness testing where Class 356 provides for the optical type with the remainder in Class 73. Another exception involves stress analysis where Class 356 provides for the optical type absent intentional loading of the specimen. The remainder is classified in Class 73, particularly for optical stress analysis with intentional loading of the specimen. (See Subclass References to the Current Class and References to Other Classes, below.)
E. NONVISIBLE RADIATION
This class is restricted to measuring and testing involving visible light. However where the measuring or testing involves infrared or ultraviolet radiation with apparatus optical in nature and nothing peculiar to such infra red and ultra violet radiation, classification is in this class. For example, optical equipment where the radiation was claimed as ultraviolet or infra red would be classified in this class, especially methods and apparatus for the inspection of solid or liquids by charged particles and invisible radiation responsive electric signalling methods and apparatus. See also THERMOCOUPLES AND BOLOMETERS, below. (See Subclass References to the Current Class, below.)
F. FLUORESCENCE AND PHOSPHORESCENCE TESTING
The examination of fluorescent and phosphorescent material or organisms to determine their fluorescent or phosphorescent properties or the examination of invisible energy including ultraviolet light by subjecting fluorescent or phosphorescent material to invisible radiation is classified elsewhere even though the fluorescent or phosphorescent radiation is in the visible light range and the intensity and the frequency of the fluorescent or phosphorescent light is examined. Methods of determining oil presence, contamination or concentration, methods and apparatus using luminophor test material or a luminophor detector in combination with an electric signalling device responsive to the light emitted by the luminophor, methods and apparatus to irradiate a luminophor and luminscent devices, per se, are classified elsewhere. (See References to Other Classes, below.)
Fluorescent or phosphorescent apparatus used as a visible light standard and claimed as part of a visible light testing apparatus as of a comparator type and which is basic subject matter of Class 356 is classified in Class 356. The examination of the visible light, per se, emitted by fluorescent or phosphorescent materials would be classified in Class 356 when the fluorescent or phosphorescent materials or source producing the visible light is not included in the claims.
G. LASERS AND RESONANCE RADIATION
The testing with optical apparatus of a laser beam for the intensity or frequency of the visible light, per se, emitted by the laser is in Class 356 (see Subclass References to the Current Class, below). However, lasers and similar devices when they function as an amplifier of light in the visible range and laser modulator, per se, are classified elsewhere. For optical elements which control light intensity or direction on a molecular level, see classification elsewhere; for modulation involving polarized light and for light control by altering an optical medium or surface see elsewhere. Coherent light generators, per se, are classified elsewhere.
H. THERMOCOUPLES AND BOLOMETERS
Where the intensity or the frequency of invisible radiation is determined by means of a thermal detector, classification is elsewhere. Where the intensity or the frequency of visible light radiation is determined by means of a thermal detector, classification is in Class 356. Where the total energy or power in a beam of radiation is measured by a thermal detector classification is elsewhere; and where thermally emitted radiation is measured to determine the temperature of the emitting source, classification is also elsewhere, except where the radiation is limited to light, where the classification is in Class 356. (See Subclass References to the Current Class and References to Other Classes, below.)
I. BURNING
Although the burning of a combustible material is a chemical reaction, the combination of the burning of combustible material for visible light examination purposes with visible light analyzing structures of this class is in this Class 356. See References to Other Classes, below for "Combustion" and for all combustion reactions not provided for elsewhere. See also Subclass References to the Current Class, below. (See References to Other Classes, below.)
J. COUNTING
Claims to the counting of discrete particles such as blood particles, bacteria colonies, or dust particles, one at a time by numerical counting apparatus which registers the
counts corresponding to the respective particles will be found elsewhere. However, the visual counting with a scale or spacer to aid the eye is classified in this Class (356). Claims to the sizing and counting of particles such as blood particles, bacteria colonies, or dust particles, one at a time by numerical counting apparatus will be found elsewhere. The counting of undulations by means of visible light or indeterminate length material such as a web of fabric or threads, per se, for testing the weave of the web for evenness, or the thread for unevenness, or for flaws, or for optical properties or physical dimensions where the measurement is affected only by the variations of the light caused by the web or thread will be in Class 356 rather than elsewhere. The counting of particles with visible light by statistical analysis procedures instead of a one by one numerical particle count as elsewhere will be in Class 356. The sizing and counting of particles with visible light by statistical analysis procedures instead of a one by one numerical particle count as elsewhere will be in Class 356. The counting or the sizing and counting of particles with visible light by statistical methods in Class 356 involves for example, polarized light, light scattering, color testing, and reflective diffusion of light. Where a microscope is utilized to count particles, one by one, such as blood particles or bacteria colonies, see elsewhere. Where an optical element such as a lens for magnification is used in combination with a support for counting bacteria colonies, or particles such as dust see classification elsewhere for one by one counting. Where no optical element is utilized and only a support is used see this Class (356). Where a microscope having a graticule rather than a cross hair or a reticle is used to count particles one by one see this class (356). See this class (356) for supports for bacteria counters where only a light and a support for the one by one count is involved. (See Subclass References to the Current Class and References to Other Classes, below.)
K. READING AND RECORDING
The combination of an optical test of this class with a qualitative or quantitative marker or recorder is in this class. Class 356 provides for the reading visually of the information or data cards where not elsewhere provided.
Pattern or character recognition of a document or a record is classified elsewhere. Where the document analysis or verification is limited to the intrinsic properties of the record, classification is in Class 356. Systems controlled by a record and code record sensors, respectfully, are classified elsewhere. Apparatus to check hole type cards for errors in the punching or in the sorting of cards where the error check equipment is not part of a business machine is classified elsewhere. (See Subclass References to the Current Class and References to Other Classes, below.)

SEE OR SEARCH THIS CLASS, SUBCLASS:
3 28, 139.01+, 141.1+, 152.1+, 218, and 442 for optical testing with a photoelectric light detector and usually claiming either an indicator or structure to support or contain the specimen or sample under test.
32 for stress analysis where Class 356 provides for the optical type absent intentional loading of the specimen.
43 where radiation is limited to light, classification is here; where thermally emitted radiation is measured to determine the temperature of the emitting source, classification is elsewhere.
51 where measuring or testing involves infrared or ultraviolet radiation with apparatus optical in nature and nothing peculiar to infra red and ultra violet radiation.
69 for cutting blade sharpness testing where Class 356 provides for the optical type.
71 where document analysis or verification is limited to the intrinsic properties of the record.
213 and 402+ for testing with optical apparatus of a laser beam for the intensity or frequency of the visible light, per se, emitted by the laser.
244 for supports for bacteria counters where only a light and a support for the one by one count is involved.
306 for methods and apparatus for the inspection of solid or liquids by charged particles.
315 see Search Class and the notes in reference to a flame producer whose flame heats or burns a sample to cause the emission of radiation to be analyzed. (See Lines With Other Classes, "Burning", above.)
335 for the sizing and counting of particles with visible light by statistical analysis procedures instead of a one by one numerical particle count.
336 for invisible radiation responsive electric signalling methods and apparatus.
438 and 441+ for the counting of particles with visible light by statistical analysis procedures.

REFERENCES TO OTHER CLASSES

SEE OR SEARCH CLASS:
15, Brushing, Scrubbing, and General Cleaning, subclass 3.1 for machines to clean eggs, or machines to clean and assort or screen eggs.
26, Textiles: Cloth Finishing, subclass 70 for devices
facilitating the inspection of cloth.
33, Geometrical Instruments, subclass 1 for planimeter type calculators such as moment of inertia of areas, subclasses 18.1+, for scribers, subclass 121, for area integrators, subclass 125, for distance measuring, subclasses 501+, for gauges of the fixed or adjustable type, and subclass 227, for means and methods utilizing nonreflected light rays and direct sighting for determining the characteristics and mutual relationships of points, lines, angles, etc.
33, Geometrical Instruments, provides for mechanical scales and gauges which may be part of optical measuring systems. (See Lines With Other Classes, B, "Testing and Measuring Subcombinations Provided for Elsewhere.")
33, Geometrical Instruments, provides in subclass 227 for optical measurements of the light ray type within the scope of this class. (See Lines With Other Classes, A, "Optical Measuring or Testing Classified Elsewhere.")
40, Card, Picture, or Sign Exhibiting, 446 for changeable exhibitors, and subclasses 361+ for transparent film viewers.
53, Package Making, subclass 52 for automatic or triggered control of a package making machine in response to a test which may be optical, and subclasses 507+ for visual inspection means combined with package making machines.
65, Glass Manufacturing, 377 for processes of glass making with a step of visually, chemically or physically determining a chemical or physical property, subclass 38 for the process of forming a lens with a fusion bonding step, and subclass 158 for inspection means which may be optical.
72, Metal Deforming, subclass 37 for metal deforming with use of optical or transparent (e.g., viewing) means.
73, Measuring and Testing, subclass 23.1 for the examination of the effluent of a mixture of gases which has contacted a solvent or sorbent which separates the mixture into fractional components and for gas chromatography involving color determination of the Class 356 type together with some manipulation of the gas beyond the scope of Class 356, subclass 28 for analysis of solid matter in gases, subclass 29 for analysis of moisture content or vapor pressure by physical means, subclass 30 for density tests by physical means, subclass 32 for specific gravity or density testing of liquids or solids, subclass 37 for fluid pressure tests, subclasses 53.01+ for the testing of liquids or a liquid suspension of solids including sediment or foreign content, subclass 73 for determining moisture content or absorption characteristics of material, subclass 78 for hardness testing, subclasses 760+ for stress or strain testing of material generally, particularly subclass 800 for optical stress analysis with intentional loading of the specimen,
subclass 104 for surface and cutting edge testing generally, subclass 116 for motor and engine testing including engine parts, subclass 156 for statistical record verifying, subclass 157 for record strip sprocket hole testing, subclasses 861+ for volume or rate of flow meters, subclass 290 for liquid level or depth gauges, subclass 488 for speed or acceleration testing generally, subclasses 700+ for fluid pressures gauges, and subclass 421 for samplers and tollers. (See Lines With Other Classes, sections A and D, above.)
73, Measuring and Testing, subclass 156 for apparatus to check hole type cards for errors in the punching or in the sorting of cards where the error check equipment is not part of a business machine. (See Lines With Other Classes, K, "Reading and Recording.")
74, Machine Element or Mechanism, subclass 20 for mechanical movement apparatus, subclass 640 for gearing arrangements, subclass 469 for control lever and linkage systems, and subclass 567 for machine elements, per se.
91, Motors: Expansible Chamber Type, subclass 1 for signals, indicators or inspection means including visual inspection devices whereby the motor operation or the condition of some part may be ascertained.
92, Expansible Chamber Devices, subclass 5 for signals, indicators, or inspection means whereby the expansible chamber operation or the condition of some part of the device may be ascertained.
95, Gas Separation: Processes, 1 for processes of gas separation with control responsive to sensed condition which may involve an optical test and subclasses 82+ for processes of gas separation using chromatography.
96, Gas Separation: Apparatus, 101 for chromatography type apparatus for gas separation, subclass 413 for gas separation apparatus having sampling means, and subclasses 417+ for gas separation apparatus having signals, indicators, measuring, or testing means.
100, Presses, subclass 99 for alarm, signal, indicator, or test means which may be of an optical character.
101, Printing, subclass 2 for printing devices combined with sorting devices which may utilize an optical test.
116, Signals and Indicators, for mechanical signals and indicators, particularly 200 for mechanical indicators which may be part of optical measuring systems and subclass 137 for compressional wave generators. (See Lines With Other Classes, B, "Testing and Measuring Subcombinations Provided for Elsewhere.")
116, Signals and Indicators, for signal and indicating apparatus which may involve optics. (See Lines With Other
Classes, A, "Optical Measuring or Testing Classified Elsewhere.")
118, Coating Apparatus, 663 for automatic control of coating apparatus which may include an optical test, subclasses 712+ for testing, inspecting or measuring which may involve visual inspection or an optical test device, and subclasses 712+ for signals and indicators responsive to a condition.
119, Animal Husbandry, subclass 6.8 for egg candling methods and apparatus combined with the treating of fertilized eggs, and subclass 311 for incubators which include candling operations.
125, Stone Working, subclass 30 for working precious stones.
131, Tobacco, 280 for cigar and cigarette making machinery which include light testing devices to control the operation of the machinery.
134, Cleaning and Liquid Contact With Solids, subclass 113 for such apparatus with an alarm, signal, indicating, inspecting, illuminating, or display means.
136, Batteries: Thermoelectric and Photoelectric, 243 for photoelectric primary batteries.
137, Fluid Handling, subclass 2 for processes of flow control by a condition or characteristic of a fluid which may be of an optical nature, and subclass 93 for self-proportioning or correlating systems responsive to an optical property, and subclass 551 for indicators, registers, recorders, alarms, or inspection means including visual inspection means.
141, Fluent Material Handling, With Receiver or Receiver Coacting Means, subclass 83 for testing or weighing receiver content, and subclass 94 for signals, indicators, recorders, inspection means, and exhibitors permitting inspection of the material handling means.
156, Adhesive Bonding and Miscellaneous Chemical Manufacture, subclass 64 for methods with measuring, testing or inspecting, subclass 378 for apparatus with testing, measuring alone or in combination with indicating means involving the properties, dimensions, or a condition of the work or apparatus, and subclass 379 for inspecting with or without illuminating means for observing normally nonvisible machine or work parts.
162, Paper Making and Fiber Liberation, subclass 198 for processes involving measuring, inspecting alone or in combination with testing or visual inspection of the product, and subclass 263 for apparatus to detect some condition of the machine or the material including inspection of the material undergoing treatment for some chemical or physical
characteristic.
165, Heat Exchange, 11.1 for exchange apparatus having an alarm, indicator, signal, register, recorder, test or inspection means.
166, Wells, 250.01 for processes including indicating, testing, measuring, locating, or recording a well condition, and subclass 64 for well apparatus including time, distance, temperature, or counting apparatus.
171, Unearthing Plants or Buried Objects, subclass 15 for apparatus including separation by size, subclass 18 for apparatus for separating buried objects based upon physical differences, and subclass 20 including visual inspection of the buried object.
173, Tool Driving or Impacting, subclass 20 for apparatus including means to indicate or signal a condition including position or movement of the driving or impacting tool.
174, Electricity: Conductors and Insulators, subclass 11 for electrical apparatus including a fluid or vacuum with structure to signal or indicate some condition of the fluid or vacuum.
175, Boring or Penetrating the Earth, subclass 40 for apparatus with signalling, indicating, testing or measuring including invisible radiation examination in subclass 41 and visual inspection means in subclass 49.
177, Weighing Scales, appropriate subclasses for balances, per se, and automatic weighing devices, particularly subclass 45 for apparatus including alarms or signals in addition to the weight indicator, and subclass 50 for apparatus for performing an additional test including size gauging not provided for elsewhere.
193, Conveyors, Chutes, Skids, Guides, and Ways, appropriate subclasses for nonpowered type material transporting apparatus including subclass 2 for chutes and subclass 35 for rollerways.
194, Check-Actuated Control Mechanisms, subclass 207 including apparatus for the testing of paper currency for genuineness and other anomalous checks in automatic dispensing machines and including apparatus in subclasses 224 and 304+ for coin in circuit operated switches, subclasses 219+, 230+, and 239+ for coin operated switches, and subclasses 302+ for fraud preventive devices.
198, Conveyors: Power-Driven, subclass 502 for a conveyor having signalling or indicating means or means for measuring the conveyed load, subclasses 504+ for a conveyor having load weighing means, and appropriate subclasses for different types of conveyors or systems of conveyors having operation control means using a photo-optics system.
200, Electricity: Circuit Makers and Breakers, subclass 61.02 for light actuated switches.
204, Chemistry: Electrical and Wave Energy, 450 and 600+ for processes and apparatus, respectively, dealing with electrophoresis and electro-osmosis; subclasses 400+ for electrolytic analysis and testing apparatus; and subclasses 242+ for electrolytic cells, in general.
209, Classifying, Separating, and Assorting Solids, particularly 510 for the combination of a candling operation with a weighing operation of the sorting type; subclasses 556+ for diverse condition responsive testing means; subclasses 525 and 586 for light-type gauging apparatus; subclasses 580+ for apparatus for sorting on the basis of an optical property of a material including the color and polarization effects of the material; subclasses 512+, 592+, and 645 for automatic weighers; and subclasses 702+ and 939 for manual candling and assorting apparatus.
210, Liquid Purification or Separation, subclass 635 and 656+ for processes involving chromatography, and subclass 85 for apparatus including alarms, indicators, registers, recorders, signals or inspection means including sight glasses.
211, Supports: Racks, appropriate subclasses for supports for plural articles particularly subclass 10 for racks to facilitate the sorting of articles by hand, and subclass 14 for racks designed to support eggs.
221, Article Dispensing, subclass 2 for apparatus including recorders, registers, indicators, signals or exhibitors for noting a condition or position of a dispenser part, and subclass 155 for apparatus with transparent inspecting or viewing means.
225, Severing by Tearing or Breaking, subclass 41 for manual severing devices which have a housing for the work supply with an inspection window or transparent panel.
226, Advancing Material of Indeterminate Length, subclass 100 for apparatus with an alarm, signal, or indicator to sense a condition in the movement of indefinite length material.
228, Metal Fusion Bonding, subclass 56.5 for apparatus to note the physical state or location of the work, flux, filler, or product.
235, Registers, 419 for record controlled electromechanical calculators, subclass 61 for mechanical digital and analogue calculators.
235, Registers, 375 and 435+ for systems controlled by a record and code record sensors, respectfully. (See Lines With Other Classes, K, "Reading and Recording.")
239, Fluid Sprinkling, Spraying, and Diffusing, subclass 71 for apparatus having means to indicate a condition, indicate the extent of motion or position of a part, or perform a quantity measurement or an inspection to determine flow conditions.
242, Winding, Tensioning, or Guiding, subclass 357, 472.9+, 479.9+, 484.8, 484.9, 534+, 563+ for detector or stop for controlling various winding or unwinding operations, and subclass 912 for an alarm or indicator.
246, Railway Switches and Signals, subclass 20 for block signal systems, subclass 111 for grade crossing track protection, subclass 120 for the detection of defects in the roadway, subclass 122 for train position indicating apparatus, subclass 125 for electric automatic highway signal apparatus, and subclass 169 for train defect indicating apparatus including infrared hot box detectors.
248, Supports, appropriate subclasses for single article supports in general.
249, Static Molds, subclass 53 for apparatus including static gauges, levels, plumbs or scale markings on molding apparatus.
250, Radiant Energy, subclass 200 for photoelectric circuits to control the illumination falling upon the photocell or to follow a pattern or to follow a point, and for apparatus, subclass 206 for photoelectric controlled circuits, particularly subclass 216 for optical or prephotocell systems which includes in subclass 221 for system controlled by articles, persons or animals, in subclass 225 polarizing optical system, in subclass 226 optical systems including visible light filters, prisms, and diffraction gratings and in subclass 229 the control of light by optical shutters and attenuators, and subclasses 250 to 422 for methods and apparatus dealing with the production of invisible radiant energy, its detection or utilization. (See Lines With Other Classes, B, "Testing and Measuring Subcombinations Provided for Elsewhere.")
250, Radiant Energy, subclass 200 provides for photocells and associated circuitry together with optical structure which may involve measuring or testing. (See Lines With Other Classes, A, "Optical Measuring or Testing Classified Elsewhere.")
250, Radiant Energy, subclass 301 for methods of determining oil presence, contamination or concentration, subclass 361 for methods and apparatus using luminophor test material or a luminophor detector in combination with an electric signalling device responsive to the light emitted by the luminophor, subclasses 458.1+ for methods and apparatus to irradiate a luminophor and subclasses 453.11+ for luminscent devices, per se. The examination of fluorescent and
phosphorescent material or organisms to determine their fluorescent or phosphorescent properties or the examination of invisible energy including ultraviolet light by subjecting fluorescent or phosphorescent material to invisible radiation is in Class 250 even though the fluorescent or phosphorescent radiation is in the visible light range and the intensity and the frequency of the fluorescent or phosphorescent light is examined. (See Lines With Other Classes, F, "Fluorescence And Phosphorescence Testing.")
250, Radiant Energy, where the intensity or the frequency of invisible radiation is determined by means of a thermal detector. (See Lines With Other Clases, H, "Thermocouples And Bolometers.")
252, Compositions, subclass 62.3 for barrier layer device compositions, subclass 501.1 for light sensitive emissive or conductive compositions, subclass 299 for liquid crystal containing optical filter compositions and subclasses 582+ for other optical filter compositions, and subclasses 301.16 through 301.6 for fluorescent or phosphorescent compositions.
264, Plastic and Nonmetallic Article Shaping or Treating: Processes, 1.1 for methods for forming articles producing optical effects including light polarization, and subclass 40 for methods with measuring, testing, or inspecting some variable condition in the shaped article, the mold, the molded material or shaping surface.
269, Work Holders, subclass 8 for magnetic work holders, subclass 11 for holders provided with illuminating means, and subclass 19 for holders provided with gage means such as vertical or horizontal position indicators for the work or the holder.
313, Electric Lamp and Discharge Devices, subclass 94 for photo-sensitive discharge devices. (See Lines With Other Clases, B, "Testing and Measuring Subcombinations Provided for Elsewhere.")
318, Electricity: Motive Power Systems, subclass 18 for follow-up systems of motor control, particularly subclass 28 for self-balancing network controls, subclass 480 for apparatus which includes the radiant energy control of a motor, and subclass 490 for motor systems with signals, meters, recorders and testing devices.
324, Electricity: Measuring and Testing, appropriate subclasses for the measurement or the testing of electric properties, particularly 300 for measurements or tests relating to nuclear or electronic induction, subclasses 403+ for the testing of lamps, vacuum tubes, and discharge devices, subclass 200 for tests which rely on magnetic phenomenon, subclasses 600+ for the measurement of impedance, admittance, inductance, resistance, conductance, and susceptance, subclasses 76.11+ for measuring or testing
electricity, per se, including subclass 96 for tests utilizing optical principles to determine electrical quantities, and subclass 121 for cathode-ray type indicators. (See Lines With Other Classes, A, "Optical Measuring or Testing Classified Elsewhere.")
324, Electricity: Measuring and Testing, for electrical indicating and measuring devices which may be part of optical measuring systems. (See Lines With Other Classes, B, "Testing and Measuring Subcombinations Provided for Elsewhere.")
329, Demodulators, appropriate subclasses for a demodulator of signals of less than infrared frequency which may contain an optical device (e.g., an optical isolator).
330, Amplifiers, subclass 4.3 for lasers and similar devices when they function as an amplifier of light in the visible range and laser modulator, per se. (See Lines With Other Clases, G, "Lasers snd Resonance Radiation.")
338, Electrical Resistors, subclass 15 for photoconductive resistors responsive to infrared, ultraviolet or visible light.
340, Communications: Electrical, subclass 146.2 for digital comparator systems, subclasses 825.30+ for intelligence comparison of information, subclasses 870.01+ for telemetric signaling means useful in transmitting a measured quantity, not limited to any particular measuring instrument provided for in other classes, and also 870.01+ for quantitative telemetering systems including subclasses 870.28+ whereby the telemetering is transmitted by means of radiant energy, subclasses 870.16+ wherein the telemetering system is responsive to a condition, subclasses 500+ for condition responsive indicating systems, particularly subclasses 577+ for a flame indicator; subclasses 603+ for a fluent material indicator; subclass 670 for a velocity indicator; subclass 675 for a web, film, or strip indicator; subclass 678 for a geometrical gauge indicator, and subclass 265 for geometrical gage type responsive systems.. (See Lines With Other Classes, B, "Testing and Measuring Subcombinations Provided for Elsewhere," (1) Note.)
340, Communications: Electrical, for electrical indicating and measuring devices which may be part of optical measuring systems. (See Lines With Other Classes, B, "Testing and Measuring Subcombinations Provided for Elsewhere.")
340, Communications: Electrical, for signal and indicating apparatus which may involve optics. See, for example, 584, 600, 630, and 632, for temperature, radiant energy, smoke, or gas indicators, respectively. (see Lines With Other Classes, A, "Optical Measuring or Testing Classified Elsewhere.")
342, Communications: Directive Radio Wave, Systems and (e.g., Radar, Radio Navigation), subclasses 1-205 for radar
systems involving electromagnetic radiation in the radio wave frequency.
346, Recorders, for the generic class of recording the movements of machines or making a record of any phenomenon, particularly subclass 33 for recorders combined with external recorder operating means, subclasses 150.1+ for electric recording including spark and electrochemical, subclasses 107.1+ for light or beam recording.
347, Incremental Printing of Symbolic Information, 112 for electrostatic marking, particularly subclasses 129+ for photo scanning; subclasses 224+ for light or beam marking processes or apparatus.
348, Television, 135 for television systems utilized to effect a measurement and subclasses 180+ for measuring and testing devices utilized in television systems which may include optical elements.
348, Television, 135 and 180+ for television systems for measuring and testing which may include optical elements. (See Lines With Other Classes, A, "Optical Measuring or Testing Classified Elsewhere.")
351, Optics: Eye Examining, Vision Testing and Correcting, subclass 204 for interpupillary distance measuring and lens positioning examination instruments, and subclasses 239+ for test charts and targets for the subjective testing of vision for astigmatism and chromaticity.
351, Optics: Eye Examining, Vision Testing and Correcting, 200 for eye examining and testing instruments which may include optical measuring or testing. (See Lines With Other Classes, A, "Optical Measuring or Testing Classified Elsewhere.")
352, Optics: Motion Pictures, appropriate subclasses for methods and apparatus dealing with cameras for taking of pictures and projectors which show the motion pictures, especially subclass 39 for methods of utilizing motion pictures for time and motion studies or for other uses other than the creation of the illusion of motion.
353, Optics: Image Projectors, appropriate subclasses for projection apparatus which may be used to facilitate optical measuring and testing.
358, Facsimile and Static Presentation Processing, subclasses 1.1-1.18 for data processing for static presentation on fixed medium (e.g., for printer).
359, Optics: Systems (Including Communication) and Elements, 350 for optical elements usable in the infrared or ultraviolet range, subclasses 362+ for combpound lens systmes including telescopes, microscopes, or periscopes, subclasses 396+ for microscope slides, subclasses 436+ for scale or
indicia reading, subclasses 483+ for polarization type devices, subclasses 290+ for light control systems which after an optical medium surface, or interface, subclasses 566+ for diffractions gratings subclasses 557+ for light interference systems, subclass 615 for light dispersion systems, subclasses 645+ lenses, particularly subclass 801 for lenses combined with illumination and a viewed object support, subclasses 227+ for light control systems using an opaque element or medium movable in or through the light path, subclasses 831+ for prioms and their mounts, subclasses 838+ for reflectors, and subclasses 885+ for optical filters. (See Lines With Other Classes, B, "Testing and Measuring Subcombinations Provided for Elsewhere.")
359, Optics: Systems (Including Communication) and Elements, for optical elements which may be used in measuring and testing apparatus. The conventional optical elements such as lenses, prisms, and mirrors are there. (See Lines With Other Classes, B, "Testing and Measuring Subcombinations Provided for Elsewhere.")
359, Optics: Systems (Including Communication) and Elements, for optical elements which control light intensity or direction on a molecular level, 246, 281+, and 301+ for modulation involving polarized light, and subclasses 290+ for light control by altering an optical medium or surface. (See Lines With Other Clases, G, "Lasers and Resonance Radiation.")
359, Optics: Systems (Including Communication) and Elements, for utilizing a microscope to count particles, one by one, such as blood particles or bacteria colonies, and for where an optical element such as a lens for magnification is used in combination with a support for counting bacteria colonies, or particles such as dust; see Class 359 for one by one counting. (See Lines With Other Classes, J, "Counting.")
361, Electricity: Electrical Systems and Devices, 173 and 211 for electric circuits for relays and electromagnets controlled by a photosensitive device.
362, Illumination, appropriate subclasses for general purpose lighting devices, particularly 3 for photographic lights, subclasses 138+ for inspection lamps, and subclass 293 for signal lanterns.
365, Static Information Storage and Retrieval, appropriate subclass for static information storage and retrieval systems, per se. Static storage systems which include testing or measuring are excluded from this class.
372, Coherent Light Generators, for coherent light generators, per se. (See Lines With Other Classes, G, "Lasers snd Resonance Radiation.")
374, Thermal Measuring and Testing, subclass 32 for thermal measurement of total energy or power radiated from a source;
and subclasses 121+ for emitted radiation, in general.
374, Thermal Measuring and Testing, subclass 32 where the total energy or power in a beam of radiation is measured by a thermal detector; and subclasses 121+ where thermally emitted radiation is measured to determine the temperature of themitting source, except where the radiation is limited to light, where the classification is in Class 356. (See Lines With Other Classes, H., "Thermocouples And Bolometers.")
376, Induced Nuclear Reactions: Processes, Systems, and Elements, 245 for the testing, sensing, measuring, monitoring or detecting of a reactor condition including control of the reactor as a result of the testing or sensing.
377, Electrical Pulse Counters, Pulse Dividers, or Shift Registers: Circuits and Systems, subclass 6 for article counters of the electrical type.
377, Electrical Pulse Counters, Pulse Dividers, subclass 10 for counting of discrete particles such as blood particles, bacteria colonies, or dust particles, one at a time by numerical counting apparatus which registers the counts corresponding to the respective particles. (See Lines With Other Classes, J, "Counting.")
382, Image Analysis, appropriate subclasses for the application of image analysis or pattern recognition systems.
382, Image Analysis, for pattern or character recognition of a document or a record. (See Lines With Other Classes, K, "Reading and Recording.")
385, Optical Waveguides, appropriate subclasses for fiber optics, per se.
395, Information Processing System Organization, 1 for artificial intelligence processing, subclasses 118+ for computer graphics processing, subclasses 200.01+ for digital data processing, and subclasses 326+ for a computer operator interface.
396, Photography, subclass 563 for a sensitometer which may produce an optical wedge having varying light transmission characteristics by the controlled exposure of a photographic medium to light.
399, Electrophotography, 9 for diagnostics of electrophotographic devices.
414, Material or Article Handling, appropriate subclasses for the generic class of article handling, particularly 431 for engaging an article between its ends for rotation and advancement, and subclass 433 for article rotators, roller type.
422, Chemical Apparatus and Process Disinfecting, Deodorizing, Preserving, or Sterilizing, 50 for analytical and analytical-control apparatus involving an optical test; subclass 44 for viable blood-treating apparatus; and subclass 99 for laboratory apparatus. An alternative electronic search of U.S. patents based upon a modification of the European Patent Office Classification (ECLA) System for certain subject matter in this subclass may also be found in Class 422 Cross-Reference Art Collections 908-948. (There are no definitions associated with these Cross-Reference Art Collections. The most available disclosure as to the types of documents contained herein is given in any notes associated with the titles.)
423, Chemistry of Inorganic Compounds, for all combustion reactions not provided for elsewhere. (See Lines With Other Classes, I, "Burning.")
424, Drug, Bio-Affecting and Body Treating Compositions, 9.1 for compositions and methods of diagnosing a body condition by an in vivo test.
427, Coating Processes, subclass 162 for processes of coating, per se, wherein the product is an optical element.
428, Stock Material or Miscellaneous Articles, appropriate subclasses, for a stock material product in the form of a single or plural layer web or sheet which may possess a critical light transmissive or reflective property; and especially subclass 426 for nonstructural composite web or sheet embodying a layer of glass.
430, Radiation Imagery Chemistry: Process, Composition, or Product Thereof, subclass 24 for radiation imagery chemistry process involving control feature responsive to a test or measurement.
431, Combustion, subclass 13 for gas burners with signal, alarm or indicator for controlling the combustion ingredients or any other function relating to the burning of the gas, and subclass 355 for laboratory type burners including those used in sample excitations dealing with spectroscopy and flame photometers of Class 356.
431, Combustion, subclass 4 for feeding a substance to the flame additional to the normal fuel and oxidizing material to act as a protective agent or to give the flame some special characteristic, subclass 126 for apparatus with ornamental forms, surface ornamentation or an additive or additive means producing flame coloration, and subclass 355 for apparatus comprising a vertical tube of constant cross section with a fuel gas feed means and an opening for air admission at its lower end, the fuel being fed upwardly and vertically into the tube, mixing air, and discharging from the upper end to burn thereabove. (See Lines With Other Classes, I, "Burning.")
433, Dentistry, subclass 6 for the visual comparison of tooth forms with the shape or coloring of a person's face or teeth.
434, Education, Demonstration, and Cryptography, subclass 298 and 303 for apparatus and processes relating to chemistry and physics which could include light testing devices, subclasses 98+ for color comparison charts which are used for display and instruction purposes, and subclasses 322+ for examination devices and methods which may include as a part thereof reflection and transmission tests similar to those found in Class 356.
435, Chemistry: Molecular Biology and Microbiology, 4 for the quantitative or qualitative testing of fermentation processes.
436, Chemistry: Analytical and Immunological Testing, 1 for analytical and analytical control methods which could involve an optical test.
445, Electric Lamp or Space Discharge Component or Device Manufacturing, subclass 4 and 64 for methods and apparatus for adjusting electrodes by means of optical operations.
451, Abrading, 42 for a lens grinding process which may include optical tests as part of the grinding process and subclass 325 for a stationary tool type of lens grinder.
505, Superconductor Technology: Apparatus, Material, Process, 150 for high temperature (T[subscrpt]c[end subscrpt] > 30 K) superconducting devices, and particularly subclasses 160+ for measuring or testing system or device.
600, Surgery, 310 for surgical diagnostic instruments which may involve optical measuring or testing on or in the body, including in vivo light examination of a body process, including metabolism, spirometers, and endoscopes.. (See Lines With Other Classes, A, "Optical Measuring or Testing Classified Elsewhere.")
604, Surgery, 20 for subject matter relating to administration or removal of material from the body by means responsive to optical diagnostic means.
606, Surgery, 2 for subject matter relating to surgical instruments, or their use, for applying light to the body.
607, Surgery: Light, Thermal, and Electrical Application, 1 for therapeutic instruments which utilize light.
700, Data Processing: Generic Control Systems or Specific Applications, subclasses 90-306 for particular application of data processing systems or calculating computers.

GLOSSARY:
DIFFRACTION
The bending of a light ray in passing the edge formed by contiguous opaque and transparent edges.
DIFFUSE
Pertaining to the scattering or random deviation of transmitted or reflected light.
ELECTROPHORESIS
The effect in which charged particles suspended in a liquid are moved under the influence of an electrostatic field.
FIDUCIAL
A reference direction formed as by a light ray, level, compass, or scale from which another direction is measured or compared.
LIGHT, VISIBLE LIGHT
Visible light is radiation, which stimulates the optical receptors of the eye, and has a wavelength from 3850 to 7600 Angstrom units. The term light in these definitions refers to radiation in the above mentioned range, and when qualified by the terms ultraviolet and infrared refers to the corresponding radiation ranges adjacent the visible range.
MEASURING-TESTING
Measuring usually involves a more precise and quantitative determination of the characteristic or property in question. Testing may be a mere indication of the presence or absence of the characteristic or property, and may involve only a mere inspection or viewing of the phenomenon or specimen. It should be recognized that the two terms overlap to some extent in meaning.
MENSURATION
Measurement of lengths, areas, or volumes.
MONOCHROMATOR
An instrument for producing a narrow band of the spectrum by dispersing a radiation beam into its components or colors, and isolating the narrow band desired as by passing the components or colors through a narrow slit.
OPTICAL ELEMENT
A structure which performs a basic optical function. See Class 359 for a more specific definition.
OPTICAL SYSTEM
A combination of two or more similar or diverse optical elements which are optically related, or an optical element combined with nonoptical structure where the overall function performed is optical in nature. The optical systems in this class are for measuring or testing purposes.
OPTICS, OPTICAL
The science of light and vision and the construction of optical instruments.
REFLECTION
The return of light striking a surface back into the medium from which it came.
REFRACTION
The deviation of light which results when a ray of light passes obliquely from a medium of one density to a medium of another density.
SPECTRUM
The band of colors produced by separating white light into its component frequencies. The term also denotes radiation arrayed over a frequency range where the frequency of the radiation continuously increases or decreases over the range.

This subclass is indented under the class definition. Subject matter including structure responsive to two stereoscopic images as photographed or otherwise viewed at spaced points over a surface (usually of the earth) and furnishing a contour plot of the surface based on the distinctions in these images.
(1) Note. The subject matter of this subclass usually involves a photodetecting apparatus such as a photocell system which scans or otherwise responds to the stereoscopic images or records, together with apparatus to compare the photocell outputs to operate some form of indicator such as a recorder. If the indication is by a scriber, classification is in Class 33; and if the output is an error signal as for alignment purposes classification is in Class 250, especially subclass 558.

SEE OR SEARCH THIS CLASS, SUBCLASS:
138 for general alignment inspection.

SEE OR SEARCH CLASS:
33, Geometrical Instruments, 20.1 for sight line controlled geometrical scribers.
250, Radiant Energy, subclass 220 for photocell systems with plural photocells responsive to plural related images where the measuring is lacking.
348, Television, subclass 26 for television systems including means to generate contours based on features in the scene viewed.
353, Optics: Image Projectors, subclass 5 for projection involving mapping or aerial photograph rectifying.
359, Optics: Systems (Including Communication) and Elements, subclass 470 for stereoviewers with compensation for camera positions, as of the plotting or mapping type.

RANGE OR REMOTE DISTANCE FINDING:
This subclass is indented under the class definition. Subject matter comprising instruments to measure the distance between an observer and a remote point or to measure the distance between two points remote from the observer.
(1) Note. Height is a distance that may be measured.

SEE OR SEARCH THIS CLASS, SUBCLASS:
496 for interferometric dimensional measurement of small structure or spaces.

SEE OR SEARCH CLASS:
235, Registers, subclass 414 for means to calculate the range of a target and not employing a particular sighting means.
348, Television, 135 for television systems utilized to determine range.
396, Photography, 89 for range finders which operate in conjunction with camera structure.

Triangulation ranging to a point with one projected beam:
This subclass is indented under subclass 3. Subject matter including the following: (a) the distance to any single remote target point is determined in accordance with the principles of triangulation; (b) the target may include several points requiring more than one beamed measurement; and (c) a light beam or its reflection from the target point is oriented and projected to form at least one side of a triangle.
(1) Note. Triangulation involves, for example, establishing a triangle where one side (i.e., the base) and the angles, which the two other sides form with the base, are determined.
(2) Note. This subclass does not necessarily require the use of a photodetector, but requires a projected beam.
(3) Note. This subclass includes, for example, apparatus that utilizes together a nonfixed axial source and a nonfixed axial line of sight for the sensing that is not found elsewhere, but that still requires only a single source for each point.

SEE OR SEARCH THIS CLASS, SUBCLASS:
3.09 where scanning is required to achieve angular measurement to a single point.
3.12 for photodetection remote from at least two source locations that are transmitting beams to be received by a photodetector.
9 for triangulation with no projected beam and no photodetection.
372 for distance measurement to define the dimensions of an adjacent, as opposed to remote, article that may involve triangulation to any one point.

SEE OR SEARCH CLASS:
250, Radiant Energy, subclass 201.6 for triangulation used to establish distance-related focus of the source onto a triangulating photodetector.
342, Communications: Directive Radio Wave Systems and Devices (e.g., Radar, Radio Navigation), for the use of similar circuitry not requiring the same wavelength or radiation distinctions.
367, Communications, Electrical: Acoustic Wave Systems and Devices, for the use of similar circuitry not requiring the same wavelength or radiation distinctions.
396, Photography, 89 where triangulation may be employed in the focus of a separate photographic camera.

Using photodetection with a fixed axial line of sight:
This subclass is indented under subclass 3.01. Subject matter that determines an angle of the triangle with respect to a known base line by establishing a fixed viewing direction and field of view for a photodetector to generate an electrical signal upon the coincidence of the target along a photodetector's line of sight.
(1) Note. This subclass would include apparatus that utilizes a moving detector with respect to a fixed optical viewing axis to determine the direction of light from a targeted source.

Using a source beam with a fixed axial direction or plane:
This subclass is indented under subclass 3.01. Subject matter that includes a beam or plane of light from the target that has a fixed angular orientation with respect to a baseline to establish an angle of the triangle.
(1) Note. The use of a photodetector is not required for this subclass, but the use of a vidicon-type detector is found here.

SEE OR SEARCH THIS CLASS, SUBCLASS:
3.05 for a system that includes a moving optical axis in the receiver optics and a fixed detector.

With a single staring photodetector having one element:
This subclass is indented under subclass 3.03. Subject matter wherein a detector produces an electrical signal related to the angular position of the source based on the instantaneous output of or differential output across a single detecting element that is not subdivided for its operation.
(1) Note. A one-element photodetector may consist of a lateral effect or photoresistive element.

SEE OR SEARCH THIS CLASS, SUBCLASS:
3.03 for vidicon-type detection.
3.06 for use of detectors that define the position of incidence of received light by the difference in the outputs of more than two detector elements (e.g., at least three separate photodetectors).

Having moving receiver optics:
This subclass is indented under subclass 3.04. Subject matter wherein an image of the source is moved with respect to the detector's axial line of sight to achieve an effective movement of the photodetector's angular field of view across the source.

SEE OR SEARCH THIS CLASS, SUBCLASS:
3.02 for systems that may include a moving detector element with respect to a fixed optical line of sight.

With a single photodetector having multiple elements:
This subclass is indented under subclass 3.03. Subject matter wherein a detector produces an electrical signal related to the angular position of the source based on the output of a particularly positioned one of an array of at least three subelements in the focused field of view of a single detector structure.

SEE OR SEARCH THIS CLASS, SUBCLASS:
3.03 for vidicon-type detection.
3.07 for CCD-type multi-element detectors that are electronically scanned.
3.08 for two separated detectors that are paired.

Having electronic scanning of the photodetector:
This subclass is indented under subclass 3.06. Subject matter that includes electronic regular sampling through time of the elements of the detector array in order to determine
the position or angle associated with a particular element illuminated by the target.
(1) Note. This subclass includes, for example, CCD-type detectors.

SEE OR SEARCH THIS CLASS, SUBCLASS:
3.03 for vidicon-type detection.

With at least one paired set of staring photodetectors:
This subclass is indented under subclass 3.03. Subject matter wherein any two separated detectors produce electrical signals related to two angular positions detected from the single source.

SEE OR SEARCH THIS CLASS, SUBCLASS:
3.06 for a single detector subdivided into at least three subelements.

Requiring scanning of a source beam:
This subclass is indented under subclass 3.01. Subject matter wherein the source comprises a beam of light that is moved at some angular rate that can be detected and associated with any one target's angular position.
(1) Note. The target may be at the source position or reflected by the source, but scanning is required to generate the angular information.

SEE OR SEARCH THIS CLASS, SUBCLASS:
3.02 for moved but not necessarily spatially scanned sources that define a target with respect to a fixed axial line of sight of a photodetector.

Triangulation ranging to a point with two or more projected beams:
This subclass is indented under subclass 3. Subject matter wherein a target distance is determined in accordance with the principles of triangulation, and two light beams,
separated by a known baseline distance, are oriented and projected to define the other two legs of the triangle.
(1) Note. The two beams may be scanned over angularly related time across the target or moved at least once to orient their coincidence on the target.
(2) Note. Triangulation involves, for example, establishing a triangle where one side (i.e., the base) and the angles, which the two other sides form with the base, are determined.
(3) Note. This subclass does not necessarily require the use of a photodetector, but requires projected beams.

SEE OR SEARCH THIS CLASS, SUBCLASS:
3.09 where scanning is required to achieve angular measurement to a single point.
3.12 for photodetection remote from at least two source locations transmitting beams to be received by a photodetector.
9 for triangulation with no projected beam and no photodetection.
372 for distance measurement to define the dimensions of an adjacent, as opposed to remote, article that may involve triangulation to any one point.

SEE OR SEARCH CLASS:
250, Radiant Energy, subclass 201.6 for triangulation used to establish distance-related focus of the source onto a triangulating photodetector.
342, Communications: Directive Radio Wave Systems and Devices (e.g., Radar, Radio Navigation) for the use of similar circuitry not requiring the same wavelength or radiation distinctions.
367, Communications, Electrical: Acoustic Wave Systems and Devices, for the use of similar circuitry not requiring the same wavelength or radiation distinctions.
396, Photography, 89 where triangulation may be employed in the focus of a separate photographic camera.

Using photodetection at the source station(s):
This subclass is indented under subclass 3.1. Subject matter wherein an electrical signal is generated based on the
reflection of the two beams from the target back to the plane, platform, or station(s) that supports the beams and the photodetector.

Using photodetection remote from the source station(s):
This subclass is indented under subclass 3.1. Subject matter wherein an electrical signal is generated based on the incidence of the two sources onto a photodetector that is not located on the same plane, platform, or station(s) as the two sources.
(1) Note. The detector may be located at the target to receive direct unreflected directional beams of illumination from the sources.

Triangulation ranging with photodetection, but with no projected beam:
This subclass is indented under subclass 3. Subject matter wherein the distance to any single remote target point is determined in accordance with the principles of triangulation, wherein at least one passive image of a target point (which may be formed by arbitrary target point illumination) forms at least one side of a triangle.
(1) Note. Triangulation involves, for example, establishing a triangle where one side (i.e., the base) and the angles, which the two other sides form with the base, are determined.
(2) Note. The target point may be an active omnidirectional beacon source or may be actively illuminated where the active beam does not form one side of the triangle measured.
(3) Note. Sequential views of a moving target with a known speed may comprise the target.

SEE OR SEARCH THIS CLASS, SUBCLASS:
3.12 for photodetection remote from at least two source locations transmitting directed beams to be received by a photodetector.
9 for triangulation with no projected beam and no photodetection.
372 for distance measurement to define the dimensions of an adjacent, as opposed to remote, article that may involve
triangulation to any one point.

SEE OR SEARCH CLASS:
250, Radiant Energy, subclass 201.6 for triangulation used to establish distance-related focus of the source onto a triangulating photodetector.
342, Communications: Directive Radio Wave Systems and Devices (e.g., Radar, Radio Navigation), for the use of similar circuitry not requiring the same wavelength or radiation distinctions.
367, Communications, Electrical: Acoustic Wave Systems and Devices, for the use of similar circuitry not requiring the same wavelength or radiation distinctions.
396, Photography, 89 where triangulation may be employed in the focus of a separate photographic camera.

Using at least a pair of viewing axes:
This subclass is indented under subclass 3.13. Subject matter which includes two optical axes relating to the target directed to at least two photodetectors or detector arrays in the generation of a pair of electrical signals related to the triangle that defines the distance to the target.
(1) Note. The detector(s) may be mono- or multi-element, and further scanned or staring.
(2) Note. This subclass includes passive image correlation of two images from a single target source in establishing two angles to the target.

SEE OR SEARCH THIS CLASS, SUBCLASS:
3.08 for a pair of staring mono- or multi-element detectors used where a single source maintains a fixed axial direction.
3.15 for image correlation where a photodetector views images of a target and where one of the images is established along a fixed line of sight.
4.04 for split-image separation detection of "focus" quality where there is no baseline separation between the separate image viewing axes as here in subclass 3.14.

SEE OR SEARCH CLASS:
348, Television, subclass 139 for triangulation of range derived from two or more picture images generated and
compared based on their baseline separation.

With one viewing axis fixed:
This subclass is indented under subclass 3.14. Subject matter wherein one optical axis that views the target is fixed relative to the other one of the pair of viewing axes.

With moving optical elements in all viewing axes:
This subclass is indented under subclass 3.14. Subject matter that includes movement of each viewing axis in order to achieve measurement of the target point.

With photodetection:
This subclass is indented under subclass 3. Subject matter that includes the generation of an electrical signal in response to light associated with the distance being measured.
(1) Note. This subclass includes first any apparatus or method that includes a generic capability applicable to any one of pulse, phase, or frequency ranging systems.

SEE OR SEARCH THIS CLASS, SUBCLASS:
3.01 for a system that involves triangulation, even though that term is not mentioned, but is evidenced by a baseline or trigonometric technique and contains either photodetection and/or the use of a projected light beam.
9 for a system that uses neither a pro jected beam nor photodetection.
372 for distance measurement to define the dimensions of an adjacent, as opposed to remote, article that may involve similar ranging techniques to any one point.

SEE OR SEARCH CLASS:
342, Communications: Directive Radio Wave Systems and Devices (e.g., Radar, Radio Navigation), for the use of similar circuitry not requiring the same wavelength or radiation distinctions.
367, Communications, Electrical: Acoustic Wave Systems and Devices, for the use of similar circuitry not requiring the same wavelength or radiation distinctions.

Of a simulation or test:
This subclass is indented under subclass 4.01. Subject matter that includes a predefined range path for the light used to measure range in order to calibrate or test a range finder.
(1) Note. The simulation in this subclass is not considered the same as the alternate reference path used in subclasses 5.12 and 5.13 used during the regular operation of those range finders.

SEE OR SEARCH THIS CLASS, SUBCLASS:
72 for other optical tests not specifically dedicated to range or distance finders.

Of focused image size or dimensions:
This subclass is indented under subclass 4.01. Subject matter that includes a determination of the distance of or to an observed object by the relative focused size of the object or dimensional spread of reference points on the focal plane of the photodetector with respect to a calibrated size and corresponding distance.
(1) Note. The image size must be derived from a focused image as opposed to a blur circle size.

SEE OR SEARCH THIS CLASS, SUBCLASS:
4.04 for blur circle size or edge detection.
21 for the same, but without photodetection.

SEE OR SEARCH CLASS:
348, Television, subclass 140 where a picture image signal is analyzed for size.

Of degree of defocus:
This subclass is indented under subclass 4.01. Subject matter that includes a determination of the distance of a remote point or observed object by the degree of image focus through relative characteristics of in-and-out-of-focus intensity, blur circle size, lateral split image displacement, etc., of an image generated at some fixed location from focusing optics along its optical axis relative to the same characteristic under a focused condition at the same location along the optical axis.

SEE OR SEARCH THIS CLASS, SUBCLASS:
3.14 for split images of a single object directed to two detectors separated by a baseline, unlike split-image focus detection here in subclass 4.04 where there is no baseline separation.
4.03 for a focused image feature measurement(s).
4.05 for mechanically searching for the focal point based on the same or other characteristics as in subclass 4.04.
22 for split images without photodetection.

Of focal point search:
This subclass is indented under subclass 4.01. Subject matter that includes a way to mechanically, or otherwise, sample the "image" along the optical axis of a fixed focus lens or scan the focus of a transmitted beam to determine the point of maximum focus of the image or reflection of the source which is proportional to the distance to the targeted remote point.

SEE OR SEARCH THIS CLASS, SUBCLASS:
4.04 for determining range based on the focus characteristics of an image at some fixed point from the focusing lens.

Of differential amplitude at two source or detector distances:
This subclass is indented under subclass 4.01. Subject matter that includes either two sources at different distances from a target alternately illuminating the target at the remote point that a fixed detector views or includes
two detectors at different distances receiving focused images of the target illuminated by a single source from which distance is determined based on the relative intensities detected.

Of intensity proportional to distance:
This subclass is indented under subclass 4.01. Subject matter that includes a measure of the relative intensity of the received focused target image from which distance may be determined by the fact that intensity varies by the inverse square of the distance or the like.

Of height relative to a light plane:
This subclass is indented under subclass 4.01. Subject matter that includes some apparatus between two remote points being measured that defines the height between the ground and a detector or reflector moved to intersect a light beam or beam plane that may be scanned or fanned.
(1) Note. The apparatus may define a path for the light beam to traverse from the mirror intersecting the plane to the ground.

Of light interference fringes:
This subclass is indented under subclass 4.01. Subject matter wherein the photodetection is in response to an interference pattern formed by the interaction of coherent light waves which relate to range by a fringe pattern or fringe count.

SEE OR SEARCH THIS CLASS, SUBCLASS:
5.09 for a system that detects frequency of modulation to determine range where the beat frequency of a mixed or compared beam is not directly related to a coherent interference fringe count.
5.11 for phase change counting between known frequencies of modulation that are unrelated to coherent carrier mixing in the production of fringes.
5.15 for a system that demodulates a return beam by coherent
or incoherent mixing in order to shift the return to a different IF operating frequency unrelated to counting of fringes.
28.5 for a system where frequency is detected from the mixing of coherent waves that produce a moving, interference pattern or just a difference frequency, which is related to velocity.

Having different frequency sources:
This subclass is indented under subclass 4.09. Subject matter that includes at least two light beams from the same or different sources, but which have different frequencies.

Of pulse transit time:
This subclass is indented under subclass 4.01. Subject matter including means for measuring the time delay of a discrete light pulse in its time of flight (transit time) from an observing station to a remote point and back to the observing station.

Having return coincide with swept display or detector:
This subclass is indented under subclass 5.01. Subject matter wherein the return pulse's reception time is related to transit time by reference to where it appears in time on a calibrated sweep of a display screen, detector, or film which begins a sweep at the instant of transmission.

Having one or more return pulse gates or windows:
This subclass is indented under subclass 5.01. Subject matter including means at the receiver for accepting return signals to be processed if they occur during specified (gate or window) periods after the transmission of a light pulse.

Including a displayed image:
This subclass is indented under subclass 5.03. Subject matter wherein the return pulse includes image data of a reflecting object at the remote point and is displayed as at least a two-dimensional image that does not include reflection signals outside the gate period.

SEE OR SEARCH CLASS:
348, Television, subclass 31 for backscatter reduction of an image that may involve range gating, but does not involve range indicating.

Having pulse transmission trigger significance:
This subclass is indented under subclass 5.01. Subject matter including details of the manner in which the transmitted pulse instant is determined for measuring the transit time of the light pulse.

Including optical pick-off of transmission start:
This subclass is indented under subclass 5.05. Subject matter wherein the instant of pulse transmission is determined by optically detecting the transmission pulse in order to begin measuring the transit time.

With specific counter type timing of returns:
This subclass is indented under subclass 5.06. Subject matter including an electronic element that counts timing pulses associated with travel of the optical pulse to and from the target.

Including specific counter type timing of returns:
This subclass is indented under subclass 5.05. Subject matter including an electronic element that counts timing pulses associated with travel of the optical pulse to and
from the target.
(1) Note. This subclass includes electrical initiation of the counter controlled independently of the optical pulse itself.

Of frequency difference:
This subclass is indented under subclass 4.01. Subject matter that either sends a defined frequency beam or frequency modulates an outgoing pulse or continuous wave optical beam in order to compare the detected return frequency to the transmitted frequency for determining range calibrated frequency differences.

SEE OR SEARCH THIS CLASS, SUBCLASS:
4.09 where frequency is detected from the mixing of coherent waves that produce an interference pattern, which includes moving or static fringes which are counted.
5.15 where optical demodulation by heterodyning or homodyning is used to reduce the processed signal frequency.
28.5 where frequency is detected from the mixing of coherent waves that produce a moving interference pattern or just a difference frequency, which is related to velocity.

Of CW phase delay:
This subclass is indented under subclass 4.01. Subject matter that incorporates a continuous wave (CW) of modulated or unmodulated optical signal that is transmitted to and reflected from a target, such that the relative phase position of the returned wave is compared to the phase of the transmitted wave in order to determine the distance-proportional transit time to and from the target.
(1) Note. Phase nulling techniques are included in this subclass.

Having multiple carrier or modulation frequencies:
This subclass is indented under subclass 5.1. Subject matter including more than one frequency of modulation or carrier
frequency for the transmitted optical signal to further define the distance-proportional phases comparison.

Including an alternating reference path:
This subclass is indented under subclass 5.11. Subject matter that incorporates a path of known distance through which the transmitted signal is alternately sent in order to phase calibrate the receiver circuity for the received measuring signal from the target.

Having an alternating reference path:
This subclass is indented under subclass 5.1. Subject matter that incorporates a path of known distance through which the transmitted signal is alternately sent in order to phase calibrate the receiver circuity for the received measuring signal from the target.

Having polarization discrimination:
This subclass is indented under subclass 5.1. Subject matter that incorporates polarized optical elements in the optical path.

Having specific IF mixing of returns:
This subclass is indented under subclass 5.1. Subject matter that incorporates demodulation by optically or electrically heterodyning the received signals to an intermediate frequency (IF) for further processing.

SEE OR SEARCH THIS CLASS, SUBCLASS:
4.09 for systems that mix the return with another beam to produce a fringe pattern to be counted and frequency analyzed as a direct measurement of range.
5.09 for systems that detect frequency of modulation to determine range where the beat frequency of a mixed or compared beam is not directly related to a coherent
interference fringe count or to CW phase delay.

This subclass is indented under subclass 3. Subject matter comprising means for testing or indicating the condition of the range or height finder with regard to its adjustment, alignment, or calibration.

SEE OR SEARCH THIS CLASS, SUBCLASS:
124 for lens or reflective image former testing generally.

This subclass is indented under subclass 3. Subject matter wherein the instrument has two axis which are offset from each other in a direction perpendicular to the base line so that the device may function as a periscope.

SEE OR SEARCH CLASS:
359, Optics: Systems (Including Communication) and Elements, 540 for periscopes, per se.

This subclass is indented under subclass 3. Subject matter wherein the range or height finder is combined with a view finder.
(1) Note. Where the operation of the range finder is coordinated with the operation of some other element of the camera (usually the objective lens) classification is not here but in Class 396, subclasses 148+.

SEE OR SEARCH CLASS:
396, Photography, 148 for camera structure combined with a rangefinder and viewfinder; see also (1) Note above.

This subclass is indented under subclass 3. Subject matter wherein the range or height finder includes a base line as a part of the instrument with plural lines of sight directed from the extremeties of the base line to the point whose range is to be measured, at least one of the lines of sight being deviated.

This subclass is indented under subclass 9. Subject matter wherein filters or light valves are employed to aid the eye as in determining coincidence of the right and left images.

SEE OR SEARCH CLASS:
359, Optics: Systems (Including Communication) and Elements, 227 for diaphragms and shutters, and subclasses 885+ for filters of the color and neutral density type.

This subclass is indented under subclass 9. Subject matter wherein the range finder is combined with means to determine the height of the object whose range has been determined.

This subclass is indented under subclass 9. Subject matter wherein the observer sees the field of view in three dimensions, the range being determined by comparing the depth of the object whose range is to be measured with the apparent depth of a mark or marks superimposed upon the field of view.

SEE OR SEARCH CLASS:
359, Optics: Systems (Including Communication) and Elements, 462 for stereoscopic systems generally.

This subclass is indented under subclass 12. Subject matter where the observer sees an image in true perspective and also one in reverse perspective.

This subclass is indented under subclass 12. Subject matter where the measuring mark or marks are stationary.

This subclass is indented under subclass 9. Subject matter wherein the range measurement is made by varying the length of the base line.

This subclass is indented under subclass 9. Subject matter wherein the range measurement is made by deviating one of the lines of sight by means of an adjustable refracting element.

This subclass is indented under subclass 9. Subject matter wherein the range measurement is made by deviating one of lines of sight by means of the rotation of a reflecting element.

This subclass is indented under subclass 9. Subject matter comprising structural details including means for mounting, supporting or adjusting the range finder or its components.

SEE OR SEARCH THIS CLASS, SUBCLASS:
6 for testing the alignment or calibration of the instrument.

This subclass is indented under subclass 9. Subject matter including prism structure for displacing relative to each other the two images of a coincidence type range finder.
(1) Note. Such prism structure is appropriately classified here as a pertinent subcombination even though no other range finder structure is recited.

This subclass is indented under subclass 3. Subject matter wherein the complete measurement requires the knowledge of some distance or interval external to the measuring instrument.

SEE OR SEARCH CLASS:
33, Geometrical Instruments, appropriate subclasses, particularly subclass 262, 276, and 284, for similar subject matter with no significant optical feature.

This subclass is indented under subclass 20. Subject matter where there is an interval of known size (e.g., height of an object) at a remote point, the distance to which point is to be determined; or where the distance to a remote point is known and the size of some interval at the remote point is to be determined.

This subclass is indented under subclass 21. Subject matter where the instrument provides two displaced images of the same object for viewing by the observer.

This subclass is indented under the class definition. Subject matter comprising means whereby the relationship between periodic changes in light intensity or direction and the motion of a body are utilized in observing the body or performing some measurement with regard to the body or some means controlling the light source.
(1) Note. Where a specific test is provided for in another class, classification is in that class even though the subject matter may include a stroboscope. See Search Class notes below.

SEE OR SEARCH CLASS:
73, Measuring and Testing, subclass 1.56 for timing apparatus for watches, camera shutters and the like which may utilize stroboscopic principles.
315, Electric Lamp and Discharge Devices: Systems, appropriate subclasses for electric lamp and discharge device systems in general.
324, Electricity: Measuring and Testing, subclass 75 for calibration of electric meters using stroboscopic principles, and subclasses 76.11+ for measuring electric properties using stroboscopes.

This subclass is indented under subclass 23. Subject matter including reflecting or refracting means which are moved periodically to vary the direction of a light beam.

SEE OR SEARCH CLASS:
359, Optics: Systems (Including Communication) and Elements, 197 for scanning means in general which use a periodically moving reflecting or refracting element.

This subclass is indented under subclass 23. Subject matter
wherein the periodic motion of an element containing alternate opaque and transparent areas is used to interrupt a light source.

SEE OR SEARCH CLASS:
359, Optics: Systems (Including Communication) and Elements, 227 for light valves utilzing an opaque element movable through a light path.

This subclass is indented under subclass 25. Subject matter where the opaque element vibrates or oscillates.

This subclass is indented under the class definition. Subject matter including means to measure the velocity or the velocity to altitude ratio of a vehicle by sighting from the vehicle on a remote object, or including means to measure the velocity or the velocity to altitude ratio of a moving object remote from an observer by sighting on the object.
(1) Note. The vehicle may be a surface vehicle or an aircraft. The term "sighting" includes aiming an optical instrument with a photocell. This subject matter includes timing the passage of a sighted object over grids.

SEE OR SEARCH THIS CLASS, SUBCLASS:
459 for interferometric measurement of angular velocity.

SEE OR SEARCH CLASS:
235, Registers, subclass 413 for means to calculate the velocity of an object and not employing a particular sighting means.

This subclass is indented under subclass 27. Subject matter wherein the measuring system includes means responsive to the received light.

SEE OR SEARCH THIS CLASS, SUBCLASS:
3 for range or height finders with light detectors.
139.01 for devices measuring the angle with respect to a remote point having specified applications with photodetection.
141.1 for devices measuring the apex of an angle at a photodetection station with respect to a remote point.
152.1 for devices measuring the apex of an angle at a point remote from a photodetection station.

SEE OR SEARCH CLASS:
343, Communication: Radio Wave, subclass 8 for systems for measuring velocity by means of reflected radio wave energy.

Of light interference (e.g., interferometer):
This subclass is indented under subclass 28. Subject matter wherein the detection means is responsive to an interference pattern formed by the interaction of coherent light waves.
(1) Note. This subclass includes heterodyne interferometers which measure a doppler-shifted beam reflected from a moving object.

SEE OR SEARCH THIS CLASS, SUBCLASS:
4.09 and 4.1, for light interference measurement of displacement or distance over large distances.
35.5 for material strain analysis by light interference measurement.
450 for light interference measuring and testing, per se.

SEE OR SEARCH CLASS:
73, Measuring and Testing, subclass 71.3 for vibration sensing with a light beam indicator.

This subclass is indented under the class definition. Subject matter comprising means whereby a device for determining a line of sight relative to a remote point
includes an optical element or reticle which is moved relative to the device in accordance with the relative velocities of the device and remote point.
(1) Note. This subclass includes in general sighting devices containing optical elements which move relative to the device as a whole for the purpose of tracking a relatively moving object and also optical elements or reticles which are moved in accordance with information obtained by tracking the object by means of moving the sighting device as a unit.

SEE OR SEARCH THIS CLASS, SUBCLASS:
27 for optical devices which actually measure velocity.

This subclass is indented under the class definition. Subject matter including a support for a crystal or gem for examination by visible light, a light source passing light through or reflecting light from the crystal or gem and usually structure to view, mark, or locate the light patterns correlated to some condition of the crystal or gem.
(1) Note. Included in this subclass are apparatus and method claims which include nominal cutting or etching structure or steps to prepare the crystal for examination in addition to the claimed test.
(2) Note. The optical testing of piezoelectric and semiconductor crystals are included in this subclass.

SEE OR SEARCH THIS CLASS, SUBCLASS:
36 for sample preparation wherein the novelty is in the preparation of the sample for an optical test and not provided for elsewhere.
72 for an optical test combined with another are device and not provided for elsewhere.

SEE OR SEARCH CLASS:
29, Metal Working, subclass 25.35 for piezoelectric device making methods, which include cutting and etching steps.
125, Stone Working, subclass 12 and 13.01 for apparatus and methods for cutting crystals which include the step of first examining optically and marking the crystal for axis orientation. Also, see subclass 35 for work supports for cutting the crystal.
156, Adhesive Bonding and Miscellaneous Chemical Manufacture, 625 for methods including a chemical etching step.
378, X-Ray or Gamma Ray Systems or Devices, 73 for methods and apparatus for X-ray analysis of crystals which may include a support for the crystal.

This subclass is indented under subclass 30. Subject matter wherein the properties of crystals or gems are examined for one of the three principle axis of the crystal, the left or right handedness of the crystal, the polarity or the crystal faces, or twinning, if present, in the crystal.

SEE OR SEARCH CLASS:
216, Etching a Substrate: Processes, for the etching of a crystal or gem.

This subclass is indented under the class definition. Subject matter for examining an article or material by noting the effect of the strain in the stressed article on light associated with the article or material.
(1) Note. The light may be passed through or reflected from the article or material, or may be modified by changes in the contour or the position of markings thereon. The modification of the light may be in intensity, direction, polarization, color, or interference patterns produced thereby.
(2) Note. Stress strain measuring generally is provided for elsewhere (see the Search Class notes below). However, where the changes in the material tested operate to modify the characteristics of the light associated with the test, absent intentional loading of the specimen, classification is in this Class 356.

SEE OR SEARCH CLASS:
33, Geometrical Instruments, subclass 125 for extensiometers. See the (2) note of this subclass.
73, Measuring and Testing, 763 for testing the stress or strain of material, particularly subclass 800 for optical stress analysis with intentional loading of the specimen, and
subclasses 862+ for dynamometers which are not provided for elsewhere and which do not involve the modification of the associated light. See also (2) Note above.

This subclass is indented under subclass 32. Subject matter wherein the light utilized in the examination or analysis is polarized light, or is polarized as a result of the examination or analysis.
(1) Note. Class 359, subclasses 240+ and 483 provides for polarizing structure generally whose light polarizing properties are modified by mechanical stress; while the subject matter of this subclass is restricted to the measuring or analyzing of the strain in the stressed article or material from the effect of the strain on polarized light or from the polarizing effect of light.
(2) Note. This Class 356 provides for stress-strain determinations in articles or materials where the light is directly or indirectly associated with the article or material stressed as by direct reflection from or transmission through the articles or materials, and for transmissions of the light through detectors attached to articles or materials which are naturally or forced by stress to be light birefringent as a result of the strain on the articles or materials; while Class 73, subclasses 760+, provides for stress-strain determinations generally.

SEE OR SEARCH THIS CLASS, SUBCLASS:
30 for crystal or gem examination wherein polarized light testing may be involved.

SEE OR SEARCH CLASS:
73, Measuring and Testing, subclass 133 and 763+ for stress-strain testing apparatus and dynamometers generally where no polarized light is involved. See also (2) Note above.

This subclass is indented under subclass 33. Subject matter wherein the test apparatus utilized in examining articles or materials includes a detector which is naturally birefringent or forced by stress to be birefringent, and means to attach the detector to the articles or materials so that the strain
placed on the articles or materials is imparted to the detector so that the modification of the light associated with the detector is indicative of the strain in the stressed article or material.

SEE OR SEARCH THIS CLASS, SUBCLASS:
51 where infrared and ultraviolet light is involved in the test.
364 for polarized light examination apparatus which produces interference patterns created by the interaction of beams of polarized light.

SEE OR SEARCH CLASS:
359, Optics: Systems (Including Communication) and Elements, 483 for polarizing structure generally. See also (1) Note of subclass 33.

This subclass is indented under subclass 33. Subject matter wherein there is means to support transparent sheet material, statically or in motion, which exhibits birefringent properties naturally or when under strain, means to direct polarized light through the sheet material, and generally polarized light analyzing means to examine the sheet material.

SEE OR SEARCH THIS CLASS, SUBCLASS:
429 for monitoring of webs for optical properties or flaws.

By light interference detector (e.g., inter-ferometer):
This subclass is indented under subclass 32. Subject matter including means responsive to an interference pattern produced by the interaction of coherent light waves with the stressed article or material.

SEE OR SEARCH THIS CLASS, SUBCLASS:
4.5 for light interference measurement of displacement or distance over large distances.
28.5 for light interference measurement of velocity.
450 for light interference measurement, per se.

This subclass is indented under the class definition. Subject matter involving preparation or conditioning of an article or substance or a sample of the article or substance to facilitate or enable the later optical test and in combination with such an optical test, wherein the preparation or conditioning is significant and is not provided for in any other class.

SEE OR SEARCH CLASS:
73, Measuring and Testing, particularly subclass 23 for gas analysis and 53.01+ for the testing of liquid or liquid suspension of solids, and subclass 421 for samplers and tollers for gases and liquids including closed conduit type samplers.
422, Chemical Apparatus and Process Disinfecting, Deodorizing, Preserving, or Sterilizing, 50 for analyticalcontrol apparatus and apparatus which use sorbents or in which chemical reactions are produced.
436, Chemistry: Analytical and Immunological Testing, 1 for processes involving analytical control and use of sorbents or chemical reactions.

This subclass is indented under subclass 36. Subject matter wherein moisture or other liquids are deposited on particles to enlarge them or optically modify them (e.g., improve reflection) to facilitate optical study of the particles.
(1) Note. Generally the apparatus includes pump structure to deliver a gas sample containing p