Apparatus or methods for measuring properties of infrared, visible, or ultraviolet light, for the purpose of:

G01J relates in general to the passive optical detection per se of the quantities referred to in the Definition Statement. Measuring arrangements having a configuration dictated by the particular type of sample being investigated (for example spectrophotometer units adapted to scan articles spread over the whole width of a conveyor belt), as well as the corresponding methods, are a subject-matter to be found and classified in the corresponding (application-related) fields.

Optical arrangements occur in many areas of technology. To avoid unnecessary double classification, optical systems and instruments for which specific entries exist elsewhere (for example interferometers, gas analyzers or optical elements per se) are not generally given a secondary class in G01J. Exceptionally, where a feature of general interest for G01J is disclosed, such a secondary class may be given.

G01J comprises Indexing Codes corresponding to EC classes and Indexing Codes corresponding to finer subdivisions of EC classes. Generally speaking, the classification policy in G01J is to allocate all relevant EC classes and make a correspondingly limited use of Indexing Codes (by opposition to policies in some other fields, where for example a single EC class is given and all other aspects are allocated in the form of Indexing Codes). The limited use of the Indexing Codes in G01J is defined as follows:

The Indexing Codes corresponding to EC classes (e.g. G01J 1/04, corresponding to EC class G01J 1/04) should be given to a document which should not have an EC class in G01J (because it relates primarily to another field) but which describes a side aspect of potential relevance for the subject-matter of the corresponding group (e.g. G01J 1/04).

Of the Indexing Codes corresponding to finer subdivisions of EC classes, only a limited number is used, because the classification practice has shown that not all of these Indexing Codes are necessary and that a danger of loosing in classification consistency exists, due to potential overlaps between these groups. A list of the Indexing Codes (corresponding to finer subdivisions of EC classes) to be used is appended under the headers of each section below (G01J 1/00, G01J 3/00, etc.).

Photometry per se, photodetection principles, solar radiance measurements,

goniophotometry, aspects of integrating sphere measurement theory, standard sources for perfoming photometry; e.g. relating to exposure meters, scalar irradiance meters, directionally sensitive photodetectors, sunshine monitors, laser power meters, illuminometers, standard flashing lights, domestic lighting measurements, measurement of street lighting.

In G01J 1/00, the list of Indexing Codes corresponding to finer subdivisions of EC classes and being in use is the following:

G01J 2001/0276

G01J 2001/028

G01J 2001/0285

G01J 2001/0481

G01J 2001/0485

G01J 1/0488

G01J 1/0492

G01J 2001/4238

G01J 2001/4242

G01J 2001/4247

G01J 2001/4261

G01J 2001/4266

G01J 2001/4406

G01J 2001/442

G01J 2001/4426

G01J 2001/4433

G01J 2001/444

These Indexing Codes therefore belong to the list of codes which must be considered for use during classification.

The further remaining Indexing Codes, not appearing in this list above, optionally may be considered as well, but these additional codes, being only optional, cannot be considered as a reliable help for search, because they are not complete.

Indexing Code G01J 2001/4242 is used for classifying the aspect of synchronous detection for all apparatuses of G01J.

Optical or mechanical details specific to photometry, e.g. relating to removing stray light, photometer field of view determination, pointing of a photometer, housings, user interfaces or display arrangements

Optical or mechanical details of photometers. Optical concentrators, deflectors, attenuators, conical light guides, corrugated diffusers.

Photometers having elements positioned in front of the detector for restricting the angle of incident light.

Standard light sources, e.g. relating to deuterium lamps, argon arc, tungsten filaments.

Calibration of photodetectors using these standard sources, e.g. relating to a model sky for calibration and testing, or comparison sources built in photometers for calibrating the latter.

The "arrangements of light sources" are not necessarily for calibration. This group covers documents referring to photometric devices making use of a light source, wherein details of the light source are an important part of the disclosure (for example the way the source itself is built). This is independent from any consideration as to calibration.

In addition, documents referring to the calibration of a light sensor by means of light sources which are able to impinge the detector with known and predetermined amounts of light. These light sources used for calibrating light sensors are particular light sources, and therefore are classified in this group too.

Photometers based on a comparison of a value measured through electric radiation detectors with reference light or a reference electric value, e.g. relating to signal processing details, lock in amplifiers, ratio forming circuits, automatic gain control for compensation.

Photometers, light meters, or the like, in which a second detector is used for correction, compensation, or the like.

Series connected pairs of photodiodes, or the like. Differential photometers, ratiometric photometers. AGC (automatic gain control). Automatic exposure control.

Compensation for drift of photometers by comparison with standard light sources, voltages, etc. Compensation for dirty lenses, temperature compensation.

Photometers having means for varying the intensity of a measured or a reference value in order to equalise their effects at the detectors, and wherein said means is a variable element positioned in the light path; e.g. relating to

Visual photometers in which the field of view is split to allow comparison with a standard source and which use grey wedges, adjustable slits or diaphragms, or polarisation filters which swing into the line of sight.

Printed scales for light meters.

Photographic exposure meters, graduated neutral density wedges.

Spinning sectored discs.

Polarisation photometers.

In G01J 4/00(polarization measurement), a modulating polarizer/analyzer is often inserted between the incoming light and the detector during the measurement process. The difference with the present group however is that in G01J 4/00 measurements are simply made in order to determine the polarization and are usually not compared to a reference light or electric value, as required in G01J 1/22 (subgroup of G01J 1/10).

Comparative photometers in which two different light paths or light types impinge alternately (sequentially) the eye of an observer. Comparison with standard sources are an example.

Chopper wheels, tuned fork choppers, light dividers, hinged mirrors, nutating mirrors, rotating polygonal mirrors, wheels carrying polarisation filters or colour filters.

Polarisation photometers with flicker effect, with or without a sample, should have a class in G01J 1/34.

Examples of flicker photometer : FR878647, US5936724.

Rotating polygonal mirrors : DE1239870).

Wheels carrying polarisation filters : US2450761.

Wheels carrying colour filters : US2394508.

Visual determination of colour differences by flickering, using colour filters : US2394508.

Comparative photometers in which two different light paths or light types impinge alternately (sequentially) on electric radiation detectors.

All aspects of photometers related to the electric radiation detector(s) itself, e.g. photon counters, particular photodiode types for IR astronomy, position sensitive detectors (PSD), solarimetry, power meters, measurement of light intensity of street lighting, integrating photometers for pulsed sources, sunlight dosimeters.

Photometers, light meters, etc, in which a second detector is used for correction, compensation, etc. Series connected pairs of photodiodes, etc. Photometers using photodetector arrays. Temperature compensation. Background compensation. Linearisation.

Intensity distribution of laser beams, monitoring the characteristics of laser beams. Laser power measurements. Spot size. Beam waist. Sampling of high energy laser beams.

Characteristics of a beam include power, power repartition or energy density within a cross section of the beam (near-field and far-field energy patterns), size of a cross section of the beam (spot size, beam waist, focus position, waist radius), divergence, quality of a laser beam and position of the beam (by means of electrical detectors (position sensitive detectors, quadrant detectors, etc.)).

All aspects related to the use of electric radiation detectors specific to photometry and applied to measurement of ultraviolet light, e.g. for measuring UV radiation from flames, sun lamps, sterilisation plant, or UV lasers.

Typical examples of subject matter covered by the scope of this subgroup are exposure meters for UV microlithography, UV CCDs for astronomy or weapons tracking, sunburn monitors (using electronic detectors), UV dosimetry, UV fire alarms.

All aspects of photometers using electric radiation detectors relating to electrical circuits, e.g. relating to circuits for photodiodes or photoresistors, avalanche photodiode quenching, temperature compensation, signal amplification, noise removal, signal storage, signal transfer, pulse circuits, background removal, autoranging.

Photometer circuits with capacitor for integration or for generating pulse modulated signal/digital output.

Light meters for pulsed sources, e.g. lasers. Integrating photometers. Digital exposure meters.

Example: Measurement of very low light levels : WO9900649

Photometric devices using chemical effects, wherein a change in colour of an indicator indicates the amount of received light, e.g.relating to actinometers, sunburn dosimeters,

exposure meters for photography.

Devices using fluorescence (transfer of UV light to visible light) for measuring the intensity of incoming light (use of visible detectors).

Measuring intensity of UV radiation. Flame detectors. Laser warning devices. Indicator cards for UV radiation.

Suntan gauge.

UV integrating sphere, coated with fluorescent material.

Testing of phosphors.

Actinometry.

Fibre optic UV sensing.

Example: Optical crystal which receives a narrow band visible light from a source and infrared light from a sample (light containing infrared absorption spectrum information of the sample), and transforms these two lights into a sum frequency light having a visible sum frequency image : US6687051. (The visible sum frequency image is then detected.)

Optical spectrometry, spectrophotometry. Optical spectrometers per se, independently of specific applications, e.g. relating to waveguide spectrometers, acousto-optic spectrometers, imaging spectroscopy, UV spectroscopy, holographic spectroscopy, heterodyne spectroscopy.

Colour measurement per se.

Application specific arrangements are classified in G01N 21/00.

In G01J 3/00, the list of Indexing Codes corresponding to finer subdivisions of EC classes and being in use is the following:

G01J 2003/1213

G01J 2003/1217

G01J 2003/1221

G01J 2003/1226

G01J 2003/123

G01J 2003/1239

G01J 2003/1243

G01J 2003/1247

G01J 2003/1278

G01J 2003/1282

G01J 2003/1286

G01J 2003/2866

G01J 2003/466

G01J 2003/467

These Indexing Codes therefore belong to the list of codes which must be considered for use during classification. The further remaining Indexing Codes, not appearing in this list above, optionally may be considered as well, but these additional codes, being only optional, cannot be considered as a reliable help for search, because they are not complete.

Details relating to particular optical elements of spectrometers, other than general prisms, filters, gratings and photodetectors.

Spectrometers using fibre optics.

Attachments for spectrometers, matching to cameras, correction for stray light.

Parabolic light concentrators. Collimators. Shutters.

Microscopes with beam splitters for spectrometry.

This group has a number of dedicated subgroups corresponding to each type of details. For the rare cases where a specific aspect is not foreseen, the present group is used.

All aspects relating to slits in spectrometer arrangements, e.g. relating to adjustable slits, mounting arrangements for slits, calibration of slit width, motorised slit mechanisms, reflecting slits, alignment procedures for slits, curved slits.

All aspects relating to scanning arrangements of elements of a spectrometer, e.g. relating to gratings driven by stepper motor, sinebar mechanisms, continuous rotation of a grating with shaft encoders, cam drive arrangements, fast-scan spectrometers, mechanisms for scanning a mirror or another optical element, screw-based mechanisms for coupling the movement of two optical elements.

Spectrometers having a switching mechanism for switching a light beam between sample path and reference path, for example using segmented mirror wheels or pivoted mirrors. Beam switching arrangements are arrangements for introducing sequentially light beams travelling along different beam paths into a single spectrometer.

All aspects relating to light sources or lamps for spectrometers or spectrophotometers, e.g. relating to infrared sources, glow discharge lamps, UV sources, daylight simulators, Cerenkov light source, hollow cathode lamps, pulsed sources, lasers.

This group classifies the documents which contain sufficient details about the light source(s) being used in a spectroscopic device. Sufficient details include for example constructional details, type of light source or the use of a plurality of light sources in order to make a more complete measurement.

It usually does not refer to the position of the light source.

Optical devices operating a selection of a relatively narrow spectral band out a broader spectral domain, e.g.relating to monochromators, optical filters associated to a broadband source, optical filters having a variable passband, scanning monochromators, liquid crystal optical filters, graded interference filters, rotating filter wheels or "paddle wheel" filters.

Filters being Fabry-Perot filters or linearly variable filters (wedge shape) (G01J 3/26)

The devices within this group can be placed either before the sample ("source side") or after the sample ("detection side").

Specific details about the filters are additionally given appropriate Indexing Codes in the range G01J 2003/1213 - G01J 2003/1252.

Spectrometers using prisms as dispersive element.

Autocollimating monochromators, i.e. combination of a prism with a concave mirror to produce a parallel beam of dispersed light - has the merit of allowing uniform slit width for all wavelengths.

All aspects relating to diffraction or dispersion elements in spectrometers, e.g. relating to grating based monochromators or spectrometers, toroidal gratings, plane gratings, concave gratings, double pass grating monochromators, multi-echelle grating monochromators, order sorters.

All aspects relating to Fabry-Perot cavities in Fabry-Perot spectrometers and interferometers, and linearly variable filters in spectrometry, e.g. relating to scanning Fabry-Perot interferometers, spectrometers using a wedge shaped linearly variable filter.

All aspects relating to the various types of calibration or correction of optical spectrometers and spectrophotometers, for example using deconvolution of overlapping spectral lines, derivative spectroscopy, matrix solving methods, spectral library searching, automated calibration, neural networks.

All aspects relating to detector arrays in spectrometers, e.g. relating to photodiode array spectrometers, details of CCDs for spectrometry, binning techniques, Vidicon detectors, focal position detection or spectrometer adjustment relatively to a focal point.

An imaging spectrometer collects incident light from a scene and analyzes it to determine the repartition of spectral intensities for each pixel thereof (spatial resolution of the scene).

Either a whole spectrum is measured for each pixel of a scene, or a hyperspectral image (comprising a large number of narrow spectral band spread densely over the spectrum) is produced.

An image is scanned to produce a map showing location of sources of different wavelengths. Applications to satellites.

This group can include imaging interferometers used as spectrometers.

All aspects relating to measurement techniques based on Hadamard masks or grids, e.g. relating to spectrometers having patterned windows, wherein the patterns are complementary.

All aspects of time-resolved spectroscopy, e.g. relating to time-resolved Fourier transform spectrometry.

Spectrometers using a single detector which scans. Successive spectral band detection.

Examples of scanning are a wavelength scanning filter, a detector moving through a spectrum, the use of rotating slotted wheels.

Scanning spectrophotometers.

Spectrometers for analysing several spectral bands simultaneously, wherein each band is directed at or detected by a separate detector. Can use diode array detectors. Systems employing several subareas of a large area 2D detector as separate detectors (each subarea detecting a different spectral band) are classified here.

Polychromators (detection side).

Spectral detection in two or more broads spectral ranges, for example UV-Vis-NIR spectrometers. Several different spectrometers in one.

Example of UV-Vis-NIR spectrometers or several different spectrometers in one: DE10010213.

All aspects of absorption spectrometry, where the absorption of a sample is being measured, e.g. relating to dual-beam, sample/reference cell spectrometers and spectrophotometers, reflection absorption spectrometers, grazing incidence spectrometers, absorption spectrometers using logarithmic amplifiers or ratio circuits,

cavity ring down spectroscopy (CRDS), nonlinear spectroscopy like two-photon absorption (TPA), THz (Terahertz) spectroscopy)

All aspects of derivative spectroscopy, wavelength, amplitude or phase modulation spectroscopy, phase switching spectroscopy, laser Stark modulation spectroscopy, e.g. relating to spectrometers using wobbling interference filters or a mirror vibrating on a tuning fork.

Derivative spectroscopy is mostly used for :

- Measuring low concentrations (or liquids)

- Isolate a constituent among a multiplicity of constituents

- Isolate weak emission lines

- Determine the concentration of a substance in a mixture.

Frequency-modulation absorption spectroscopy, optical heterodyne spectroscopy, e.g. using lead-salt diode lasers, tunable lasers, two-tone techniques, multi-mode lasers, a vibrating slit for wavelength modulation, tilting interference filters, double frequency modulation.

All aspects of Raman spectrometry, CARS (= coherent Raman anti-Stokes) spectroscopy,

Fourier Transform (FT) Raman spectroscopy, picosecond Raman spectroscopy.

Spectrometers for luminescence, phosphorescence, fluorescence.

Spectrofluorometers, spectrophosphorimeters, microspectrofluorimeters.

All aspects relating to scattering light spectroscopy, Brillouin scattering spectrometry,

dynamic light scattering, quasi-elastic light scattering, photon correlation spectroscopy.

Atomic emission spectrometry.

Spectroscopy based on polarisation effects. Fourier Transform polarisation spectroscopy.

Polarisation spectrophotometer for both emission and excitation.

Spectrum treatment, correction, calibration, standardization of data provided by Fourier Transform (FT) spectrometers or interferometers.

Interfaces to FT spectrometers/interferometers.

All aspects of Fourier Transform (FT) infrared, visible or UV spectrometry, e.g. involving Michelson interferometers, polarising interferometers, dual-beam FT spectrometry, static interferometers.

All aspects of cross-correlation spectrometry, dispersive correlation spectroscopy, e.g. involving mask spectrometers (devices comprising a grating and an array of slits tailored to an predetermined spectrum), cross-correlation interferograms with a Michelson interferometer. Usually, correlation of measured data of interest with measured data serving as reference (e.g. measurement at non-absorbing lines) is performed.)

Optical measurement devices and methods having the purpose of measuring colour, e.g. relating to aspects of chromaticity diagrams, colour-difference formulae, colorimetry based on physiology, checking colour fidelity of TV cameras, CIE standards, tristimulus values, colour matching, control of colour for printing.

Colour mixing, colour creation, colour reproduction using colour spinners (discs with partitions, sectors or portions of different colours).

"Visual" mixing, or mixing due to the human eye perception.

Matrix representations of colour spaces, transformations from one colour space into another, numerical corrections or manipulations within a colour space.

Colour management systems.

Colour matching methods and devices.

Colour measurements taking into account or modelling the particular perception of the human eye. Tristimulus detection, colour measurements based on the CIE colour matching functions.

Metamerism-related issues.

Colour measurement using photocells, cameras etc.

Colorimeters using a selected number of discrete wavelengths as light source to illuminate the sample.

Examples of selective illuminants are LEDs or a broadband source followed by a filter or filters (the filter(s) being provided between the source and the sample). The resulting light may not be as narrowband as for a LED, but it should be sufficiently narrow for measuring a colour without using filters on the detection side (in front of the detector(s)).

Colorimeters having movable filters positioned in front of the detectors (filter wheels).

Colorimeters having fixed filter-detector pairs.

Colorimeters using dichroic mirrors and ratio detectors (where only two wavelengths are detected and their ratio is monitored)

Colour systems in the form of color charts: OSA, DIN, Coloroid, Ostwald, CIE, BS5252, Munsell. Colour atlases, colour harmony. Farnsworth-Munsell 100-hue test. Grey scales.

Colour charts for printing. Colour charts in digital form (look-up tables).

G01J 3/52 regroups the colour charts as such (the way in which they are built, i. e. the particular presentation of colours that they allow and which answers the needs of a particular application). The way in which a colour database is structured should be classified here and includes "real" charts as well as virtual ones (computer-based)

Circular or partially circular colour charts. Charts made of one or more discs, superposed or not.

All aspects relating to the calibration of colorimeters.

Devices which help a user to determine a choice of (different) colours which harmonize together, in the sense that the global effect of these colours put next to each other is pleasing to the eye. Mostly used for showing colour combinations in the fields of interior decoration (colours of sofas, walls, ceilings, curtains...), for the choice of different colours to be applied on different parts of a car, or in the field of clothing.

All aspects relating to the choice of pleasant colour combinations, e.g. relating to choice of colours for interior decoration, choice of colours in a nail varnish simulator, charts, advertising displays, etc, for aiding choice of colour, combination of colours.

Devices using colour harmony theory. These devices rely on the definition of colour harmony, according to which n colours harmonize together when their mixture gives a grey colour. These devices are usually circular colour charts covered by a mask with a number of holes. Choosing a first colour by means of one of the holes leads to the selection of other ("harmonic") colours through the remaining holes.

Passive measurement of the polarisation state of a beam of incoming light. Measurement of degree of depolarisation.

Ellipsometric devices which send a selectable polarized light on a sample (active device) and detect afterwards the effect of the sample on the polarization state of the input light are classified in G01N 21/211. Documents about ellipsometry may only be classified in G01J if they present special or unusual ways of detecting polarization on the detection side.

Polarimeters having a spatial filter for separating an incoming light beams into sub-beams.

Aspects of polarimeters relating in particular to electric radiation detectors and processing of the detected signals. Stokes, Jones, Mueller representations of polarization states and related calculus.

Example for Mueller representations of polarization states and related calculus : US2003117624.

The measurement of temperature through analysis of the optical (infrared, visible or ultraviolet) radiation emitted by the hot body.

The measurement of temperature through analysis of the optical (infrared, visible or ultraviolet) radiation emitted by a test body directly contacting the hot body whose temperature is to be determined.

Subclasses G01J and G01K cover the measurement of temperature in general, but Subclass G01J is restricted to a particular form of thermometry, namely radiation pyrometry. In contrast, subclass G01K covers all temperature measurements of general applicability, except radiation pyrometry.

Measurement of radiant heat transfer of samples.

Optical pyrometry for flames and/or gases and/or smoke, e.g. involving temperature measurement of hydrogen flames, arcs, plasmas, temperature measurement by light scattering, fluorescence, laser beam deflection, plasma temperature profile in MHD boundary layer, remote sensing of gases temperature in the atmosphere, the use of line-reversal methods.

Non-contact temperature measurement of moving objects, e.g. steel strip, turbine blades, yarn, float glass, motor rotors, railway wagon wheel bearings. Detection of vehicle wheel spin by pyrometry.

Details about constructional aspects of non-contact temperature detection devices.

Details about optical aspects of non-contact temperature detection devices: G01J 5/08.

Elimination of stray light: G01J 5/06.

Getters: G01J 5/045.

Ear thermometer probe covers: G01J 5/021.

Ear thermometers casings: G01J 5/049.

Details about the functioning of non-contact temperature detection devices and processors for controlling such devices, e.g. G01J 5/026.

The general group: G01J 5/0011 for ear thermometers applies when neither G01J 5/049 nor G01J 5/021 is relevant.

Compact devices in "one piece", e.g. integration or encapsulation of optical and sensing elements within a package.

Illustrative example of subject-matter classified in this group:

Devices using sensor-related data during measurement or analysis. For instance, information obtained from bar codes, visual signatures, etc. on the optical elements is used to identify a specific component and its properties.

Pyroelectric null detectors using electrical balancing by a null detection method.

Devices (circuitry, memory, display, etc.) pertaining to the recording and indicating of thermal data from thermoelectric elements, resistors, thermistors, photo-emissive and photo-voltaic cells, e.g. video recording, display of thermal color temperature.

Details of housings of IR detectors. Purging arrangements, choice of thermal materials, encapsulated packages. Mounting arrangements for a pyrometer. Infrared thermometers, particularly mounts. Mounts for astronomical radiometers.

All aspects of mountings or housings of pyrometers in environments where the available space is very limited and/or where difficult measurement conditions prevail, for example due to dust or strong vibrations. Examples of such environments include car engines, exhaust pipes, furnaces, rotating machines, kilns, electron microscopes, moulds, gas turbines, microwave ovens, brakes.

Constructional details of mountings allowing for translational and/or rotational sensor movement, e.g. rails.

Means for prevention or determination of dirt, dust, smog, or clogging, e.g. from combustion taking place in furnaces, from disturbing radiation collection. This also includes cleaning optical elements before or during measurements.

Cold shields, field stops at reference temperature. Radiation shields for thermocouples.

Constructional arrangements having the effect of limiting, reducing or eliminating spurious radiation.

All aspects of non contact temperature measurement devices relating to the use of cooling or thermostating mechanisms for parts of the device, e.g. involving cryostats or vacuum vessels for IR detectors, cold shields, integrated detectors/coolers, self-cooling detectors, thermoelectric cooling, cold fingers, Dewar vessels.

Constructional arrangements for compensation of fluctuations caused by non-temperature environmental parameters (e.g. humidity, pressure or electromagnetic waves); controlling the atmosphere inside a pyrometer.

The aiming, pointing or tracking of pyrometers.

The encoding of angular position of pyrometers.

The means for aligning pyrometers or determining the field of view.

Details about optical aspects of non-contact temperature detection devices.

Optical fibre thermometry. Infrared light guides. Sighting or pointing arrangements for pyrometers.

Infrared detectors having individual concentrators and conical horn antennas : US2003089842, GB2369724

The means for restricting (selection) the range of wavelengths that are used to determine temperature by radiation pyrometry.

The means for isolating ranges of wavelengths for different purposes (discriminating), one of which is temperature measurement by radiation pyrometry. The other purposes could be monitoring (e.g. using a radiation band to monitor sensitivity while another band is used to determine temperature), calibrating, ensuring centering on the hot source (by using a radiation band associated with a specific hot source ‒ or with known noise ‒ to track the hot source ‒ or reduce the field of view to avoid sources of noise).

The optical filters, i.e. elements to select a range or band of wavelengths, specially adapted for use in radiation pyrometers.

Details about the construction of the chopper itself, e.g. relating to the chopper wheels, IR detector packages with integral shuttered windows, liquid crystal shutters, electro-optical elements for modulating IR beam, circuit arrangements (peak detection, sample and hold circuits) linked to the chopper.

Windows insulating the sensor of a radiation pyrometer from the environment.

Arrangements for fastening windows to radiation pyrometers.

Detector aspects which do not depend on the specific features of thermopiles (classified in G01J 5/12), bolometers (G01J 5/20) or pyroelectric devices (G01J 5/34), that is, which can be used with any of these detector types.

In case generic disclosures are illustrated by means of one of these particular devices (i.e. bolometer) then both a class in G01J 5/10 and in G01J 5/20 (bolometers) should be given.

All aspects of thermopile detectors (arrays of thermocouples), e.g. relating to specific geometrical arrangements of the thermocouples, cold junction temperature compensation, thermocouples consisting of tensioned wire grid, heat flux meters.

All aspects of thermopile detectors relating to electrical circuits and/or signal processing, e.g. involving linearisation of the detector's output, negative feedback to improve frequency response.

Thermopiles in which the cold junction temperature is measured (for correction purposes), or in which the cold junction is thermostated.

Other detectors having temperature compensation circuits for which no other group is foreseen are classified here too (e.g. US2004079888)

All aspects of bolometric or junction based detectors, e.g. relating to fabrication details, superconducting bolometers, bolometer arrays, diode-based bolometers, cavity radiometers.

All aspects of bolometric or junction based detectors relating to electrical circuits and/or signal processing, e.g. involving correction of bolometer drift, superconducting bolometers, bolometer bridge circuits and their compensation, pulsed bolometers, a.c. bolometers.

All aspects of photoemissive cells, i.e. light-sensitive gas-filled or vacuum tubes that operate on the basis of the photoelectric effect, and photovoltaic cells generating voltage when light strikes the junction between a metal and a semiconductor or a junction between two different semiconductors, e.g. photodiodes operating in the photovoltaic mode.

Infrared sensors based on pyroelectric effect. Details for fabrication of pyroelectric arrays, etc. Infrared CCD imaging for intruder alarms, fire alarms. Pyroelectric polymer films, LiTaO₃, Sr(1-x)BaxNb2O6, other ferroelectric materials.

Using bimetallic elements.

More generally, detectors having stacked layers of materials having different thermal expansion coefficients, the materials not being necessarily metallic.

Radiometers measuring the radiant flux of radiation based on radiation pressure or the radiometer effect, e.g. light mills (Crookes radiometer), Nichols radiometer, MEMS radiometer.

Illustrative examples of subject-matter classified in this group:

The measurement of the spatial distribution of optical radiation emitted by an object or body to infer a local temperature corresponding to different regions of that object or body.

The measurement of temperature using radiation pyrometry by wholly visual means.

The use of thermography to detect flaws is covered in general by group G01N 21/88, whereas the use of thermography specifically and solely to diagnose a medical condition is covered by group A61B 5/01. Group G01J 5/48 is appropriate whenever thermographic techniques or features of general applicability are described.

The measurement of temperature by radiation pyrometry where reference sources are used either simultaneously with the temperature measurement, e.g. disappearing-filament pyrometer, or in previous or subsequent steps, e.g. in calibration steps using standard sources. This encompasses a process of collecting radiation signals using sources the temperature of which is known, adjusting the radiation pyrometer based on these signals, and measuring the temperature of the desired object or body in the final step.

Calibration and testing of infrared imagers for temperature detection.

Reference black bodies. Reference sources per se and devices to expose detectors to be calibrated to said sources. Thermal scene projectors for testing IR imagers.

Synthesis of infrared spectral signatures.

Theory of blackbody cavities. Absolute radiometry.

Standard IR lamps. Imager with inbuilt reference source.

Array of emitters.

The nondispersive determination of temperature based on the absorption or the attenuation of the emitted radiation. The determination involves the selection of a single wavelength or wavelength band.

The determination of temperature based on the polarisation of the emitted radiation.

The thermal imaging of a body based on the polarisation of the emitted radiation.

The determination of colour temperature, i.e. detecting at least one wavelength or spectral band emitted by a hot body, comparing the detected intensity or intensities to the values theoretically expected for a black body at well-defined temperatures and determining the temperature that produces the best fit between observed wavelengths or spectral bands and theoretically expected values.

The determination of temperature through measurement of at least two wavelengths or spectral bands, where the temperature is expressed as a mathematical function of pairs of intensity-wavelength values, or of intensity-spectral band values, typically in the form of ratios of intensities. In other words, the comparison need not be performed explicitly with the Planck formula. The comparison step could involve phenomenological equations derived from the Planck formula or providing a sufficiently precise approximation of it.

When temperature is inferred from measurements of spectra, the demarcation line between subclasses G01K and G01J is the following: subclass G01J encompasses solely temperature measuring techniques where the radiation spectrum originates from black-body radiation (as modelled by the Planck formula). In contrast, whenever the spectrum results from ambient radiation or radiation from a dedicated source being reflected or transmitted by the body the temperature of which is to be determined, this subject matter is covered in subclass G01K.

Multiple-wavelength pyrometers for observing spectrum, using prisms, gratings, etc.

Spectralradiometers. Raman scattering. A finely resolved spectrum is detected either sequentially (spectral scanning) or simultaneously (snapshot detection).

All aspects of non contact temperature measurement or colour temperature measurement which is based on the detection of specific spectral bands, e.g. involving monochromatic pyrometry, or the use of band pass or narrow band filters.

Passive compensation using off-line or a posteriori calibration.

The characterisation of a radiation pyrometer in good working order to determine instrumental parameters or settings, to be able to transform the collected radiation signal into an accurate value of temperature. One example is through modelling of the pyrometer's response.

The adjustment of a radiation pyrometer by correcting for known sources of background, like emissivity, atmospheric effects or scattered radiation.

This place is used to classify the calibrating or the modelling of a radiation pyrometer, in general. When calibration is accomplished by making use of reference sources, e.g. black bodies, the relevant place is group G01J 5/52.

When it is desired to ascertain that a radiation pyrometer is operating correctly, i.e. that its output is a faithful indication of the measured entity's temperature, the relevant classification place is group G01J 5/90.

One possible criterion to distinguish calibration from testing is that calibration presumes a properly operating instrument, but with that instrument being unable to produce a precise and accurate value of temperature without being supplied with auxiliary measurements, e.g. by performing measurements in a situation where the output is known or predictable.

The testing, inspection or checking, operational or functional, of radiation pyrometers.

This place is used for subject matter linked to detecting faults or deficiencies in radiation pyrometers, preventing their correct and accurate use. In contrast, group G01J 5/80 is used to classify subject matter where the radiation pyrometer is in good working order, but requires the determination of instrument parameters, before any precise or accurate measurement may be obtained from the pyrometer.

Devices to perform extremely accurate measurements of the velocity of light.

The usual purpose of these devices is to check the validity of Einstein's theory of relativity.

Non-interferometric measurement devices and methods for measuring wavefront, phase, coherence length and/or wavelength of an incoming light beam, e.g. relating to wavefront sensors, Shack Hartmann detectors, laser diagnostics for wavelength, phase and coherence measurement, wavefront detection per se for restoration of images degraded by turbulence, wavelength stabilization of laser beams by means of non interferometric determination of wavelength.

In G01J 9/00, the list of Indexing Codes corresponding to finer subdivisions of EC classes being used is the following:

G01J 2009/0219

G01J 2009/0223

G01J 2009/0226

G01J 2009/023

G01J 2009/0234

G01J 2009/0238

G01J 2009/0242

G01J 2009/0261

G01J 2009/0265

G01J 2009/0273

These Indexing Codes therefore belong to the list of codes which must be considered for use during classification. The further remaining Indexing Codes, not appearing in this list above, optionally may be considered as well, but these additional codes, being only optional, cannot be considered as a reliable help for search, because they are not complete.

Interferometric devices for measuring wavefront, phase, coherence and/or wavelength of an incoming light beam. Mach-Zehnder, Talbot, Fizeau configurations etc, also with optical fibres.

Wavefront control with optical feedback. Phase-conjugate interferometers.

Wavemeters. Lau effect.

Differential interferometry (= shearing interferometry) for measuring phase difference per se or degree of coherence of incoming light. Talbot interferometry.

Holographic interferometry. Moire interferometry. Speckle pattern interferometry

Interferometers for measuring wavelength, phase, etc, of laser beams. Single Wavelength Detection (SWD). Vernier fringe counting.

Spectral characteristics of laser beams.

Heterodyne laser interferometry. Self-homodyne technique. Optical heterodyne detection. Fibre-optic interferometry + spectrometry.

Use of a beat frequency between a known (local oscillator) signal and an unknown signal in order to measure the wavelength of the unknown signal.

Measurements on laser pulses, e.g.