Abstract: A thermal image identification system includes an infrared emitting element having a laminate, and a power source electrically communicable with the infrared emitting element. The laminate includes an infrared emitting layer having a first side and a second side, a cover layer associated with the first side, and a backing layer associated with the second side. The laminate may also include a first heat insulating layer between the infrared emitting layer and the cover layer, a second heat insulating layer between the infrared emitting layer and the backing layer, and an infrared reflective layer between the second heat insulating layer and the backing layer. A plurality of infrared emitting elements may be arranged contiguously for coordinated operation. The infrared emitting elements may be arranged in a one-dimensional or a two-dimensional array.

Abstract: An apparatus for measuring the concentration of a substance in a specimen. The apparatus includes a housing that defines a chamber for the specimen. A radiation source mounted to the housing emits radiation at a wavelength at which the radiation is absorbed by the substance. Two spaced apart receivers are mounted to the housing. Both receivers detect radiation at the wavelength at which it is absorbed by the specimen. Two concave mirrors are disposed in the housing. The mirrors are positioned to split the radiation emitted by the source into two beams, each of the beams being directed to a separate one of the receivers and so that the paths of travel of the beams from the source to the separate receivers are of different lengths. The concentration of the substance is determined by based on the difference in radiation detected by the receivers.

Abstract: A method and device for photothermal imaging tiny metal particles which are immersed in a given medium like a living cell deposited onto a transparent glass slide. The given medium and immersed tiny metal particles are illuminated through separate phase reference laser beam and sensitive probe laser beam, with the sensitive probe laser beam including a heating laser beam undergoing through impingement on the given medium slight phase changes induced by photothermal effect due to a local heating, in the absence of any substantial phase changes to the phase reference laser beam. Illuminating is performed by focusing the separate phase reference and sensitive probe laser beam through the transparent glass slide at a given depth within the given medium and a transmitted phase reference laser beam and a transmitted sensitive probe laser beam undergoing the slight phase changes are generated.

Abstract: A thermopile-based detector for monitoring and/or controlling semiconductor processes, and a method of monitoring and/or controlling semiconductor processes using thermopile-based sensing of conditions in and/or affecting such processes.

Abstract: The velocity of a flowing gas is measured by detecting the pattern of infrared absorption of the gas stream at two locations (2,3) spaced apart in the direction of flow and measuring the time lapse between the sensing of the same radiation pattern by the first and second sensors. The velocity can be derived from the time lapse and the known distance between the sensors. In this way, the velocity of particulate-free gas flows can be measured.

Abstract: A method and apparatus for temperature-independent determination of a concentration of a probe gas in a sample over a selected temperature range between a low temperature TL corresponding to a lowest temperature expected or found in the sample and a high temperature TH corresponding to a highest temperature expected or found in the sample. In accordance with the method, a probe temperature function of the probe gas is determined over the temperature range using a first spectroscopic technique. Then, a second spectroscopic technique is selected, a reference gas is identified and a reference temperature function of the reference gas is determined using the second spectroscopic technique over the temperature range. In particular, the reference gas is identified such that a ratio of the probe temperature function and the reference temperature function is substantially constant over the temperature range.

Abstract: The invention relates to a gas analyzer comprising a measuring volume (6) for a sample gas mixture (G), a radiation source (1) for providing a beam (20) of electromagnetic radiation to pass said measuring volume, a heat sink (4) for said radiation source, at least one thermopile detector (9), at least one optical bandpass filter (10), electrical contact pins (12) for signal(s) in the housing of said detector, a thermal mass formed of a material having high thermal conductance. Said thermal mass has a cavity (21) and an outer surface (22), surrounding at least said detector housing in the cavity, being in contact with said detector housing, and extending towards the radiation source. There is a thermal barrier between the heat sink (4) and the thermal mass (8, 16). The gas analyzer further comprises electrical wires (15), which are composed of materials and having dimensions producing an overall thermal conductance substantially lower than that of said electrical contact pins.

Abstract: A method and system for identifying and calculating the percentages of gases, such as the automotive and other commercial refrigerant gases, in a gas mixture using infrared spectroscopy is disclosed. The novel system is compact, relatively inexpensive and has greater accuracy than those systems of the prior art.

Abstract: A semiconductor infrared detector includes in the following order: a semiconductor substrate; a layer of electrically insulating material; and patterns formed in a semiconductor layer. The patterns are formed from at least one island that is connected to bridges which are connected to polarization electrodes. The bridges are lines having an approximately constant width lp and the islands are zones having a width li that is greater than that of the lines.

Abstract: The invention relates to an infrared gas analyser (1), especially for use as a gas detector for leak detection using a sampling probe. Said gas analyser comprises a vessel (test vessel 2), through which a test gas flows, and an infrared light source (4, 5, 42) which produces an infrared light that shines through the test vessel (2). The analyser further encompasses a detector (35) that facilitates measurement of the infrared light absorption in the test gas. The aim of the invention is to provide at low costs an analyser that is apt for every day use. To this end, a reference vessel (3) through which a reference gas flows is provided in addition to the test vessel (2) through which the test gas flows. A reference gas is sucked from the environment of the test gas suction area. The same or an additional light source (4, 5, 42) and the same detector (35) are allocated to said reference vessel.

Abstract: Method and apparatus for providing real-time data indicative of the isotopic composition of formation fluids during drilling. The method includes the steps of: (a) providing a reference fluid having a known isotopic composition in a reference cell; (b) capturing a sample of formation; (c) providing at least one laser beam; (e) passing a beam through the reference fluid, measuring the reference-measurement beam before and after it passes through the reference fluid; (f) and passing a beam through the sample, measuring the beam before and after it passes through the sample, and calculating a first isotope concentration from those measurements. The measurements can provide information relating to the carbon isotopic composition of individual compounds in hydrocarbon gas mixtures, with the individual compounds including methane, ethane, propane, iso- or normal butane, or iso- or normal pentane.

Abstract: The apparatus for detecting the presence of a particular gas within a mixture of gases comprises first and second emitter means for emitting measurement and reference electromagnetic radiation beams respectively, which beams are activated in alternation, a measurement cell, a filter cell, first and second detector means for detecting electromagnetic radiation beams, a beam splitter, and acquisition and processing means for synchronously acquiring and processing the four signals US1, US2, UR1, UR2 delivered by the first and second detector means in succession when the first and second emitter means are respectively activated so as to determine the absolute concentration of the gas to be detected on the basis of the ratio R=(US1×UR2)/(US2×UR1) between the four signals, in which US1 and US2 respectively represent the signals delivered by the first and second detector means when the first emitter means is activated, and UR1 and UR2 respectively represent the signals delivered by the first and s

Abstract: A method for determining corrected gas flow values from measured physical gas flow values is provided. A laser-based sensor system is deployed in a duct through which the gas moves. The sensor system includes two or more pairs of photoemitters/photodetectors that emit and detect light beams. Spectral changes in the light beams associated with the laser sensor system caused by the properties of the gas passing through the duct are referenced to known gas physical properties, including density. That information as well as the velocity of the gas and the temperature in the duct are analyzed and manipulated in a programmed processing unit. The processing unit is programmed to calculate a corrected gas flow value from the information obtained directly and indirectly from the detected light beams. The system and the method for obtaining the corrected flow value are suitable for use in the determination of corrected airflow through a duct, including a duct of an aircraft engine.

Abstract: An NDIR sensor includes a cylindrical metallic tube, a printed circuit board platform that fits into one end of the tube, a diffusion filter that fits into the opposite end of the tube, and an optical system. The optical system includes an infrared source on the platform, a mirror on the inner wall of the tube so as to reflect and focus the infrared light from the infrared source, and a detector assembly that receives the infrared light after reflection. The gas sensor may further include a partition between the infrared source and the detector assembly, a removable filter on the diffusion filter, connecting pins attached to the platform, and a sealing layer formed under the platform. The detector assembly includes a signal detector and a reference detector. A first and second bandpass filters are respectively formed on the signal and reference detectors.

Abstract: A docking station for use with an environmental monitoring instrument to provide predictive diagnostic information. The docking station is connected, typically via the Internet, to a remote service center, and exposure data, calibration data and diagnostic data are communicated from the instrument to the docking station and from the docking station to the service center. Mathematical analysis of the collected data from all available sources is performed at the service center and predictive warnings are generated to alert the users of potential instrument faults, thus allowing preemptive maintenance. The analysis methods include principle component analysis and other statistical methods, fuzzy logic and neural networks. This docking station can be used with monitoring instruments for water quality, pollution control, indoor air quality and breathing air quality.

Abstract: The apparatus for detecting the presence of a particular gas within a mixture of gases comprises first and second emitter means for emitting measurement and reference electromagnetic radiation beams respectively, which beams are activated in alternation, a measurement cell, a filter cell, first and second detector means for detecting electromagnetic radiation beams, a beam splitter, and acquisition and processing means for synchronously acquiring and processing the four signals 1 U S 1 , U S 2 , U R 1 , U R 2

Abstract: In one preferred embodiment, a gas analyzer is presented that focuses light beams through gas cells without reflecting the light beams off the walls of the cells. By eliminating wall reflections, dirt or debris on the walls of the cells will not result in inaccurate gas concentration measurements. In another preferred embodiment, a gas analyzer is disclosed having removable gas cells, which allows a user to easily clean the cells instead of returning a contaminated gas analyzer to service personnel for cleaning. In yet another preferred embodiment, a gas analyzer has a purged gas flow channel between source and detector sections of the analyzer to remove contaminants that can result in inaccurate gas concentration measurements. In an additional preferred embodiment, a gas analyzer is disclosed which has a heat exchanger to equilibrate the temperature of incoming air to the temperature of the analyzer's gas cells, thereby avoiding temperature-based errors in gas concentration measurements.

Abstract: An infrared optical gas analyzer is provided with at least one infrared optical radiation source (6, 7), two multispectral detectors (1, 2) and a cuvette (12) containing the gas mixture to be measured. A process for determining gas concentrations with the infrared optical gas analyzer is also provided. The gas analyzer makes possible the simultaneous measurement and identification of a plurality of gases in a gas mixture with a compact design not prone to interference. The radiation emitted by an infrared optical radiation source (6) covers a first wavelength range [&lgr;1, &lgr;1′] and the radiation emitted by an infrared optical radiation source (7) covers a second wavelength range [&lgr;2, &lgr;2′] which is selected such that it is different from the first wavelength range. The paths of rays pass through the interior of the cuvette (12) and reach the multispectral detectors (1) and (2).

Abstract: A method and system for identifying and calculating the percentages of gases, such as the automotive and other commercial refrigerant gases, in a gas mixture using infrared spectroscopy is disclosed. The novel system is compact, relatively inexpensive and has greater accuracy than those systems of the prior art.

Abstract: An apparatus is provided for detecting each of the five known anesthetic agents, CO2, and N2O when monitoring a patient's respiratory gas stream during anesthesia. A source of infrared radiation emits the infrared tight through a gas stream and onto the infrared detector/sensor. The detector may contain ten analytical channels, each channel containing an independent infrared detector and a specific bandpass infrared filter which only permits certain wavelengths of the infrared radiation to reach the respective infrared detector. One of the channels is a blocked detector which serves as the reference point. A calibration and processing means is also provided to compensate for factors such as offset voltage, cross coupling, wideband changes and thermal drifts which may affect the accuracy of the gas measurements.

Abstract: A correction curve (FIG. 19) is prepared by plotting 12CO2 concentrations and 13CO2/12CO2 concentration ratios which are determined on the basis of a calibration curve and 13CO2 and 12CO2 absorbances of gaseous samples having the same 13CO2/12CO2 concentration ratio but known different 12CO2 concentrations. A gaseous test sample containing 13CO2 and 12CO2 as component gases is introduced into a cell, and spectrometrically measured. A 12CO2 concentration of the gaseous test sample is determined by way of the spectrometric measurement. A concentration ratio correction value is obtained on the basis of the correction curve and the 12CO2 concentration of the gaseous test sample thus determined. A measured 13CO2/12CO2 concentration ratio is divided by the concentration ratio correction value thus obtained for correction of the 13CO2/12CO2 concentration ratio. Thus, the measurement accuracy of the concentration ratios of the component gases can be improved.

Abstract: A capnometer includes an airway adaptor for introducing a respiratory gas into the analyzer, an infrared radiation source emitting infrared radiation passed through the airway adaptor, a beam splitter for reflecting and transmitting infrared radiation that impinges on the beam splitter, first detecting means for detecting the infrared radiation reflected by said beam splitter and transmitting through said beam splitter, second detecting means for detecting the infrared radiation reflected by said beam splitter and transmitting through said beam splitter; a gas cell filled with CO2 gas, said gas cell being located between one of said first and second detecting means and said beam splitter and processing means for processing a concentration of carbon dioxide gas by using output signals of said first and second detecting means.

Abstract: A non-dispersive infrared gas analyzer for determining concentrations of carbon dioxide and/or carbon monoxide, hydrocarbons, and nitrogen oxides has two measuring cells 4, 6 consecutively traversed by a beam, with an optopneumatic detector 22 for carbon dioxide and an optopneumatic detector 23 for carbon monoxide arranged between them. Detectors 7, 8 for hydrocarbons and nitrogen oxides are arranged on the measuring cell 6 located downstream from detectors 22, 23 in the direction of the beam.

Abstract: A sensor device and a method for non-dispersive analysis of gas mixtures for determining the concentration of one gas component contained therein, whose absorbency may be influenced as a result of collision broadening by other components contained in a gas mixture (GC). The device includes: a measuring chamber (5), containing the gas mixture; a radiation source (4), emitting radiation (15) through the chamber; detector (10, 14, 16) for receiving radiation passed through the chamber; optical bandpass filters (9a-c) positioned between the detectors and the radiation source, the detectors being coupled with measuring ducts (1-3) or measuring cycles. An optical gas filter (11), contains said gas component or a mixture thereof and is located between the detector and the radiation source. From the first measuring duct is obtained a first signal (S1) and from the second measuring duct is obtained a second signal (S2) relating to radiation also passed through the optical gas filter.

Abstract: A stable isotope analyzer is concentration calibrated by measuring relative proportions of isotopes in a measurement gas. The measurement gas is a component of a gaseous mixture consisting of the measurement gas and one other gas or a mixture of gases containing none of the measurement gas. First, a mixture is produced with a relatively high concentration of the measurement gas and known isotope proportions. The concentration of the measurement gas in the other gas is determined and the isotope proportion is measured to determine a point on a calibration curve (measured isotope proportion values vs. measured concentration values). At least one further point on the calibration curve is determined by diluting the measurement gas in the mixture by introducing a gas or gaseous mixture containing no measurement gas. The reduced concentration is determined and the isotope proportion measured to determine another point on the calibration curve.

Abstract: A sensor (1400) with radiation detectors (1421-1422) with two or more bolometer or photoconductor elements and bias polarity switching of one element to emulate mechanical chopping of input radiation. This electronic chopping permits higher chopping frequencies than mechanical chopping for bolometers because the scene settling time does not limit electronic chopping. The detectors may be within a single vacuum integrated circuit package with separate narrow passband filters for chemical spectral analysis.

Abstract: A laser absorption sensor system for performing optical measurements on a sample is described. The sensor system includes a tunable laser, capable of being tuned at rates exceeding 1 KHZ, and with a tuning range approaching 1 GHz. The laser beam is modulated at a modulation frequency between 1 and 100 KHz. Modulation in this frequency range is termed wavelength modulation. The beam is split into two beams, a signal beam and a reference beam. The signal beam traverses the sample where characteristic absorption takes place and is incident on a signal photodetector. The reference beam is incident directly on a reference photodetector. A noise cancellation circuit combines signal and reference photo-currents from signal and reference photodetectors reducing signal noise and increasing system sensitivity. The combination of wavelength modulation and the noise cancellation scheme provide a highly sensitive simple, rugged, low cost laser absorption sensor system.

Abstract: A method for analyzing an impurity in a gas including the steps of: introducing a gas with an impurity into a first cell; introducing a gas with no impurity into a second cell; maintaining identical pressures in the first and second cells; irradiating a light from a light irradiating source; varying the frequency of the light over a frequency spectrum including an absorption frequency of the impurity; splitting the light by a splitting device in order to pass a first beam through the first cell and to pass a second beam through the second cell; measuring the intensity of the light passing through the first cell over the frequency spectrum with a first measuring device and the intensity of the light passing through the second cell over the frequency spectrum with a second measuring device; and determining an absorption spectrum of the impurity in the gas based on the difference between data measured with the first measuring device and data from measured with the second measuring device.

Abstract: A method and apparatus for continuously monitoring and measuring the concentration of gases in a gas-containing liquid such as a transformer oil. The method and apparatus employ a passive gas extraction technique which comprises a high performance membrane material to extract dissolved gases from the oil, and an IR-based sensor to detect gases present. The passive gas extractor extracts dissolved gas from the gas-containing liquid, there being a known relationship between the concentration of a constituent gas in the extracted gas and the concentration of the constituent gas remaining dissolved in the gas-containing liquid. The gas sensor senses the concentration of a constituent gas in the extracted gas, in the presence of other constituent gases.

Abstract: Method and apparatus for measuring the quantity of sample materials which provides stable measurements for extended periods of time. A source beam containing measuring radiation and reference radiation is directed through a sample material. The measuring radiation consists of spectral energy that interacts substantially with the sample material. The reference radiation consists of spectral energy with substantially different interaction properties with the sample material. Radiation is directed along separate analyzing and normalizing information channels wherein the radiation has substantially different sample interaction. Analyzing and normalizing detectors provide responses to radiation in respective analyzing information channel or normalizing information channel. A measuring mode is established by inserting a first filter into the source beam to allow substantially only measuring radiation to propagate to the detectors, creating measuring responses.

Abstract: Method and system for measuring the relative concentrations of first and second isotopic forms of a chemical species within a sample. The present invention need not use a laser or high resolution spectrometer. The system typically includes a waveguide cell with good transmission of particular wavelengths of IR radiation, such as a hollow glass fiber waveguide cell. A source emits electromagnetic radiation, which is modulated at first and second wavelength bands that correspond to absorption bands of the first and second isotopic forms of the chemical species, respectively. In certain embodiments, the source is a filtered broad band source, such as a plurality of LEDs. In some embodiments, an FTIR spectrometer may serve as a filtered source and signal detector.

Abstract: Apparatus for the optical detection of selected toxic gases, using the ultraviolet region of the electromagnetic spectrum, and the known absorption properties of the toxic gases in the ultraviolet region. An ultraviolet flashlamp source illuminates a straight, highly polished metal tube with numerous perforations to permit access for the gas to be detected. The ultraviolet light then enters an optical compartment comprising an optical beamsplitter and two ultraviolet detectors with wavelength selective narrowband filters attached. The filters are selected so that one overlaps the region of absorption by the gas while the second is in a region where there is no absorption by the gas. The electronic circuit following the ultraviolet detectors and the drivers for the flashlamp, are timed by a microprocessor that provides the means for the electronics and data processing to be synchronized with the flashlamp pulse.

Abstract: A liquid concentration detecting apparatus which permits a real-time and high-accuracy detection of concentration of a liquid (particularly an etching or cleaning solution) used in a semiconductor plant, with a simple configuration at a low cost. The liquid concentration detecting apparatus 1 has a cell 2 to which a liquid is supplied, and a projecting section 4 and a receiving section 5 arranged opposite to each other in a direction at right angles to the axial line of the cell. A light of a prescribed wavelength is projected from this projecting section 4 through the liquid in the cell 2 to the receiving section 5, and the concentration of the liquid is determined by detecting the amount of light received by the receiving section.

Abstract: A method of non-dispersive analysis of gas mixtures for determining the concentration of some gas component therein.

Abstract: A system for monitoring combustion and pollutants developed in a combustion chamber comprising at least one longitudinal single mode laser diode emitting a beam of electromagnetic radiation with a frequency modulated around the resonance frequency of a specific spectral absorption line of a component of the combustion gases, means for directing the beam into the combustion chamber along a path through the combustion gases to a radiation sensor and processing means connected to the sensor in order to identify the temperature of the combustion gases and the concentration of the component with the specific absorption line by the measurement of the intensity of radiation transmitted at various frequencies in a region surrounding the resonance frequency.

Abstract: An infrared spectrometer for anesthetic gas monitoring using an infrared light source is divided into two separately sealed sections. A partition wall separating the two sections contains a partition window allowing infrared light to pass from the infrared source into a sealed sample chamber. In case of a failure of the sealed sample chamber the gas does not come into contact with the infrared source, thereby minmizing the risk of possible explosion. A gasket of neoprene or butyl rubber is used to seal the two sections from one another. The signal produced by the spectrometer indicating the composition of the sample gas is monitored to alert the user of a single point failure at the seal of the sample chamber.

Abstract: A gas analyzer has a simple composition and can measure multi-components at a high accuracy. A plurality of measuring cells, including a case where the cells are different in length from each other, communicate sequentially with each other through a communication part to form a single gas path. A cut-on filter as an infrared penetration/reflection means for diffracting spectrally an infrared wavelength is provided on a light source side. A NO.sub.X measuring cell 3 having a cell length of about 60 mm and a CO.sub.2 measuring cell 7 having a cell length of about 1 mm which communicate through the communication part with each other, and a capacitor microphone (an infrared-ray detector for NO.sub.X) and a pyroelectric detector (an infrared-ray detector for CO.sub.2) are provided on the infrared penetration and reflection sides of the optical filter.

Abstract: A system for measuring and monitoring water vapor concentration in a sample uses as a light source an argon discharge lamp, which inherently emits light with a spectral line that is close to a water vapor absorption line. In a preferred embodiment, the argon line is split by a magnetic field parallel to the direction of light propagation from the lamp into sets of components of downshifted and upshifted frequencies of approximately 1575 Gauss. The downshifted components are centered on a water vapor absorption line and are thus readily absorbed by water vapor in the sample; the upshifted components are moved away from that absorption line and are minimally absorbed. A polarization modulator alternately selects the upshifted components or downshifted components and passes the selected components to the sample. After transmission through the sample, the transmitted intensity of a component of the argon line varies as a result of absorption by the water vapor.

Abstract: A detector for an infrared gas analyzer is formed of first and second light receiving rooms filled with gas to be analyzed, a gas passage communicating between the first and second light receiving rooms, and a heat-sensitive resistance element disposed perpendicularly to the gas passage. The heat-sensitive resistance element includes at least one heat insulator having an opening at a center thereof, a pair of heat-wire elements disposed on the heat insulator to face against each other with a predetermined space therebetween, and a heating device. Each heat-wire element has a plurality of elongated elements disposed parallel to each other in the opening of the heat insulator, and connecting portions for connecting ends of the elongated elements for serially connecting the elongated elements. The heating device is formed on the heat insulator around the opening to equalize temperature in a space surrounded by the heat-wire elements in the opening. Accordingly, the analyzer can be operated stably.

Abstract: An apparatus for measuring isotopic ratios provides four separate optical paths for separate measurement of each of two isotopes relative to a reference signal, using spectrally resolved infrared radiation. The design permits the measurements to be made accurately without significant time lags between measurements, and without interchanging of cells or filters.

Abstract: A pneumatic infrared gas detector includes a pair of expansion chambers and a pair of pressure chambers, each of which is connected at one end thereof to the corresponding expansion chamber. Each of the pressure chambers is divided by a diaphragm into a first chamber connected to a corresponding expansion chamber, and a second chamber, such that the first chamber of one of the pair of pressure chambers is connected to the second chamber of the other of the pressure chambers through a first communication path, and such that the second chamber of the above-indicated one of the pressure chambers is connected to the first chamber of the other of the pressure chambers through a second communication path. A pair of pneumatic pressure detecting elements are provided each of which includes an electret film having one surface on which an electrode is formed, and an electrode plate disposed in opposed relationship with the electret film.

Abstract: The disclosed gas analyzer (10) provides two separate folded optical paths (16 and 18) from a single source (12) to a single detector array (14) via a polychromatic filter (26). One optical path (16) passes through a sample gas chamber (24) containing a gas to be analyzed and the other path (18) passes through a reference chamber (30) containing a reference gas. On each optical path (16 or 18), radiation from the source (12) is collected by upstream optics (22 or 28) to form a converging beam (16b, c or 18b, c), thereby reducing or eliminating the need for collection optics at the detector array (14).

Abstract: A sample system investigation system, such as an ellipsometer or polarimeter system, for use in investigating sample systems with electromagnetic wavelengths in the infrared range, and a calibration method for compensating nonidealities in multi-dimensional system rotated and non-rotated component representing matricies, are disclosed. An essentially achromatic compensator of dual-rhomb construction, which introduces a (3*LAMBDA/4) phase shift, but essentially no deviation in the direction of propagation of a polarized beam of electromagnetic wavelengths caused to pass therethrough, even when said compensator is caused to continuously rotate, is also disclosed.

Abstract: The invention relates to a process for analyzing traces of at least one impurity in a gas sample, by absorption by the impurity to be detected of a light beam emitted by a semiconductor diode laser, the beam emitted by the diode being split into at least two branched beams, one called the measurement beam which passes through the gas sample to be analyzed in a multipassage cell before being focused onto a measurement photodetector, another branched beam, called the reference beam, being along a reference path and directly focused onto a reference photodetector without encountering the gas sample, in which process the gas sample is at a pressure at least equal to atmospheric pressure, and a modulation of the supply current of the diode has been introduced, which comprises at least one function of the exponential type.

Abstract: The present invention relates to a device and method for measuring an impurity in a trace concentration in a gas to be measured by means of infrared spectroscopic analysis employing a diode laser. In order to carry out analysis with high sensitivity and high accuracy, the gas to be measured is directed into sample cell 5 and placed in a low pressure state by means of pump 16. Infrared light from the wavelength region in which strong absorption peaks from the impurity can be obtained are oscillated from the diode laser 1, and a derivative absorption spectrum is measured by passing the infrared rays through sample cell 5 and reference cell 8 which is filled with the impurity alone. The spectrum for the gas to be measured and the spectrum for the impurity alone are compared, and the impurity is identified by confirming a plurality of absorption peaks originating from the impurity. Determination of the impurity is then carried out from absorption intensity of the strongest peak.

Abstract: An ultraviolet light source is provided on one end of a cell into which a sample gas is introduced. A beam splitter for dividing beams which have been transmitted through the cell into two optical paths is provided on the other end of the cell. A first detector is provided in one optical path, and a second detector is provided in the other optical path. A gas filter filled with a component to be measured is positioned between the detectors and beam splitter so that a concentration of the component to be measured may be obtained on the basis of a difference between the output of the first detector and the product of the output of the second detector and an appointed constant. Influences resulting from components coexisting in the sample gas are reduced. Alternatively, an infrared light source may be provided on one end of a sample cell. A gas filter filled with a gas the same as the gas to be measured is provided at the other end of the sample cell.

Abstract: A gas analyzing apparatus comprises a light source (34) emitting an infrared luminous flux; a sample cell (38) which is arranged such that a sample gas is introduced therein and the infrared luminous flux emitted from the light source (34) is transmitted therethrough; and detection means (10a, 10b) which contain absorbers and are arranged such that the infrared luminous flux transmitted through the sample cell (38) passes through the absorbers and an increase in pressure according to the temperature within each of their absorber containers raised upon absorption of the infrared luminous flux by each absorber is optically detected so as to measure, based on the increases in pressure, concentrations of ingredients to be measured in the sample gas, wherein, as the absorbers contained in the detection means (10a, 10b), gases having ingredients identical to the ingredients to be measured are used, respectively.

Abstract: An infrared light beam, emitted from an infrared light source 4, arrives periodically and alternatively at a sample cell 1a and reference cell 1b through a rotating chopper 2. The beam, which travels through the sample cell 1a and reference cell 1b, is detected as a sample signal and reference signal by a detector 5. The chopper 2 has apertures 2a and 2a. Since the aperture 2a, which faces the sample cell 1a, and the aperture 2b, which faces the reference cell 1b, are each formed in an arc shape having a central angle of about 90 degrees, the amount of time for which the infrared light beam is emitted and not emitted to the sample cell 1b and the reference cell 1a are all about equal. Therefore, the non-dispersive infrared analyzer can obtain about twice the amount of information about the concentration of the gas to be measured than a conventional apparatus per one chopper rotation.

Abstract: An oil concentration meter includes a sample cell for receiving an oil sample that can be irradiated with infrared rays from a light source. A first interference filter having a design wavelength of 3.4 .mu.m is positioned before a measuring detector, while a second interference filter transmitting a band range between 1 .mu.m and 5 .mu.m is positioned in front of a reference detector. A logarithm of the ratio of the reference detector output to the measuring detector output is used for determining the oil concentration in a sample.

Abstract: A system for measuring and monitoring the concentration of oxygen uses as a light source an argon discharge lamp, which inherently emits light with a spectral line that is close to one of oxygen's A-band absorption lines. In a preferred embodiment, the argon line is split into sets of components of shorter and longer wavelengths by a magnetic field of approximately 2000 Gauss that is parallel to the light propagation from the lamp. The longer wavelength components are centered on an absorption line of oxygen and thus readily absorbed, and the shorter wavelength components are moved away from that line and minimally absorbed. A polarization modulator alternately selects the set of the longer wavelength, or upshifted, components or the set of the shorter wavelength, or downshifted, components and passes the selected set to an environment of interest. After transmission over a path through that environment, the transmitted optical flux of the argon line varies as a result of the differential absorption.