Abstract: Compensation and calibration method for a nondispersive infrared gas analyzer which includes an infrared source of radiation, a measuring path, a reference path, modulation devices, a detector for differential pressure measuring, comprises the following steps: first and prior to measurement, the reference gas having a variable basic concentration in the measuring component is forced through the reference branch and through the measuring branch and the detector is set to a zero position; next a dual calibration chamber is placed into the two reference paths while both of them are still passed through by the reference gas, one of the calibration chambers including a particular concentration in the measuring gas the other one lacking that measuring gas; now the sensitivity and amplification of the detector that obtains as a result of changes in the radiation on account of placing the calibration chamber into the reference and measuring path is adjusted, whereupon the calibration chamber is removed, reference gas

Abstract: There is provided a gas analyzer, including a radiation source, an analytical space through which passes the gas to be analyzed, at least one detector for detecting the intensity of radiation passing through the space, apparatus for facilitating the alternating introduction, into the space, of the gas to be analyzed and a reference gas having a concentration located at least in the upper half of the range of concentrations to be measured by the gas analyzer. The analyzer further includes processing apparatus, having a memory device, to process signals originating in the detector, the memory device adapted to store in a first mode of operation, signals representing instantaneous intensity values of the detected source and, in a second mode of operation, to store signals representing intensity values obtained when the analytical space is filled with the reference gas, a circuit for comparing the instantaneous values with the reference value, and an indicator device for indicating concentration.

Abstract: An optical sensor which can be used in conjunction with an automatic stripping apparatus. A plurality of sensing elements are placed in a predetermined geometrical relationship with respect to a plurality of nozzles which deliver paint stripping material. Each of the sensing elements comprises a lens system which optimizes inspection of the desired field of view while minimizing the effects of light from outside the desired field of view. The sensing elements produce optical signals which are converted into electrical signals by a plurality of optical detectors. The signal output of the plurality of detectors is analyzed using a programmable digital computer which is used to control a robotic positioning system.

Abstract: An IR-spectrometric analyzing procedure, the measuring absorbance and reference absorbance being detected simultaneously from an IR light beam conducted to pass through the sample and diffracted to a spectrum. An IR spectrometer comprising a light source (1), a sample cuvette (5), a diffraction member (6), detectors (7) and a calculating means (9) for determining the content values of the sample corresponding to the measuring absorbance, the detectors (7) having been arranged to detect the measuring absorbance and the reference absorbance simultaneously from the beam that has passed through the sample and been diffracted to a spectrum.

Abstract: An improved infrared analyzer is provided wherein an unknown specimen gas can be subjected to a measuring infrared ray and a comparative infrared ray to provide resulting signals. The system can be initially calibrated when a zero gas state is initially achieved in the sample cell, and correction factors are achieved by holding the zero gas instrument signal and an output difference between a zero gas comparison signal and the measuring signal for subsequent processing of the actual measurement of the specimen gas to provide a calibrated output signal representative of the concentration of the unknown gas.

Abstract: The photometer is calibrated by using a permanently built-in installation of four, similarly configured chambers in a good heat conducting carrier which is slidably interposed between sample and reference chambers on one hand and the detection structure on the other hand. One pair of these chambers is placed in the paths during measurement and is filled with inert gas, the other pair has one chamber filled with calibration gas, the other one with inert gas. All chambers are closed with similar windows.

Abstract: A gas analyzer (10) for detecting low concentrations of a specific gas which has a sample chamber comprising passages (14, 30, and 32) through which radiant energy is directed and which is pressure modulated by a loud speaker (36) both of which provide a radiant energy signal which is detected by a beam splitter (82) having a measurement channel (86) directed to a measurement detector (92) and a reference channel (84) with a reference cell (94), containing gas of the type being analyzed, directed to a reference detector (90). Both detectors (92, 90) produce a signal, and these signals and a cross channel normalization constant are processed by an algorithm. The loudspeaker (36) is isolated from the sample chamber by a flexible diaphragm (42) to eliminate phase changes in the pressure modulated output of the loud speaker (36).

Abstract: Self-normalization of laser spectrometers is provided by I"/I laser modulation and detection. A single tunable diode laser is frequency modulated by a high S/N ratio triangle wave, mechanically chopped, passed through an isothermal in-line gas and reference chamber absorption cell, and synchronously detected to provide the I" and I signals. The preferred embodiment discloses isotopic ratio measurements. The invention has application to quantitative trace gas measurements generally.

Abstract: An infrared gas analyzer reduces influenced results from interfering gases by utilizing a first filter system intermediate a light source and a gas cell in which the sample is located. The filter system passes light having wavelengths within absorption bands of the gas to be measured. It also reflects light having wavelengths outside of the absorption bands. A second filter system is also intermediate the light source and the first filter system. The second filter system absorbs light having wavelengths within absorption bands of an interfering component gas.

Abstract: A non-invasive apparatus and related method for measuring the concentration of glucose or other blood analytes utilizes both diffuse reflected and transmissive infrared absorption measurements and may be applied to either in vitro or in vivo sampling. The apparatus and method utilize non-dispersive correlation spectrometry and apply it to liquid blood serum analysis. Spectrally-modified near infrared light from the sample containing the analyte is split into two beams, one of which is directed through a negative correlation filter which blocks light in the absorption bands for the analyte to be measured, and the other of which is directed through a neutral density filter capable of blocking light equally at all wavelengths in the range of interest. Differencing the light intensity between the two light paths provides a measure proportional to analyte concentration.

Abstract: Infrared sensitive indicator-dilution tracer concentration, specifically, 1,2 propanediol, can be optically measured in blood drawn from the systemic arterial system to indicate lung vascular function and transcapillary transport, i.e. pulmonary blood flow, extravascular lung water, transcapillary permeability-surface area, fluid filtration coefficients, etc. that may be helpful in diagnosing lung diseases, particularly Adult Respiratory Distress Syndrome (ARDS).

Abstract: This present invention pertains to a photo-acoustic apparatus for detecting energy that exits from the end of an optical fiber waveguide device. The photo-acoustic apparatus includes a housing having an opening through which the end of the optical waveguide device extends into the housing. The gas fills the housing and is capable of absorbing energy that exits the end of the optical waveguide device. The gas increases in pressure corresponding to the energy absorbed by it. There is also a pressure sensor such as a capacitor microphone disposed in said housing which is capable of sensing the pressure of the gas and producing an electric signal proportional to the energy which exits the optical waveguide device. Alternatively, a solid absorber is disposed in the housing that absorbs energy that exits from the end of the optical waveguide device. The gas filling the housing, in this case, does not absorb any of the energy.

Abstract: A steam quality monitor measures the quality of steam flowing in a steam pipe. A measurement cell is connected in the steam pipe so that steam flows through the measurement cell. The cell has two windows aligned along an axis which is traverse to the flow axis of the steam. A source spatially arranged with the windows of the measurement cells provides IR energy which enters the measurement cells through one window and leaves through the other window so that the IR energy passes through the steam flowing in the measurement cell. An IR detector detects the IR energy as it leaves the measurement cell and provides a corresponding signal. The temperature of the steam flowing through the measurement cell is also sensed and a temperature signal provided. Circuitry derives the steam quality of the steam flowing in the steam pipe in accordance with the signal from the IR detector and the temperature signal.

Abstract: A method and appparatus for continuously measuring the concentration of at least one component of a gas sample by means of a laser for the purpose of charging the gas sample with radiation at a frequency in the range of an absorption line of the component, and employing a detector device for receiving a measurement signal corresponding to the intensity of the transmitted radiation and an evaluation circuit. A single mode laser is employed which is linearly tuned about a gas specific absorption line by means of bandwidth modulation so that at least two different intensity measurement values are obtained for the transmitted radiation from which the extinction, and thus the concentration of the gas component, is determined.

Abstract: A non-dispersive infrared gas analyzer is disclosed that accurately measures the concentration levels of a plurality of gases within a gas mixture. The analyzer includes first and second sample cells and is utilized advantageously for the measurement of NO.sub.x and hydrocarbon gas present in the exhaust of an automobile engine. The gas mixture of the exhaust is chilled before entering the first sample cell to remove a substantial amount of the water vapor from that sample cell to facilitate measurement of the NO.sub.x gas. The second sample cell receives the gas mixtue in an unchilled state to allow for accurate measurement of the hydrocarbon gas. The analyzer includes processors which are utilized to further correct the NO.sub.x measurement and which also interact with each other to provide an output data stream that is representative of the concentration levels of the gases that are being analyzed.

Abstract: A carbon monoxide detector comprises a single monochromatic infrared source which is arranged to alternately direct light through two separate gas-containing test chambers. The first chamber is supplied with gas to be tested which has an unknown carbon monoxide content. A catalytic burning chamber is connected between the first and second chambers to receive gas from the first chamber, burn the carbon monoxide in the gas to carbon dioxide and supply the carbon monoxide free gas to the second chamber. A single infrared light detector is provided for receiving light as it comes alternately from the two chambers. The light from the two chambers is compared to determine the amount of carbon monoxide present in the gas of the first test chamber. Since the same background gas is provided in both chambers and only a single infrared source and detector are utilized, inaccuracies due to differences in background detection, infrared source intensity and infrared detector sensitivity are overcome.

Abstract: The absorption analyzer of the type provided with light sources (3a, 3b), cells (1, 2) containing a reference gas and an ingredient gas to be measured, respectively and a detector (5) for determining the absorption of the light emanating from the light sources and passing through the cells, is additonally equipped with a gas filter (8) arranged in the optical path between said light sources and the detector and contains an ingredient gas with an absorption spectrum band that nearly corresponds to that of an ingredient gas to be measured or an ingredient to be measured. The advantage of the invention is that a relatively large range of concentrations of gas ingredients can be measured with the same type of cells having the same cell length.

Abstract: A source of IR radiation for use with a gas analyzer including a sealed-off enclosure containing at least one molecular, IR-active gas which, upon excitation, is capable of emitting IR-radiation of a known, discrete spectral distribution. The excitation is effected by electrical discharges taking place in a limited portion only of the sealed-off enclosure, the rest of the enclosure serving as reservoir of the gas. The electrodes producing the discharges are disposed outside of the enclosure. A gas analyzer incorporating the source is also described.

Abstract: An apparatus for intermitting beams of light for use in a gas analyzer in which a rotary shaft of a chopper is supported by first and second ball bearings. An outside ring of the first ball bearing is fixedly mounted on a bearing housing and either an inside ring or an outside ring of the second ball bearing is adapted to be movable in the thrust or axial direction relative to the rotary shaft, whereby the second ball bearing is movably energized in the thrust direction by an elastic member to eliminate shake of the rotary shaft due to play in the ball bearings and thus reduce modulation noise to improve measuring accuracy of the gas analyzer.

Abstract: Photometer with at least one measuring beam traversing a space that contains measuring gas is improved by a solid state detector made of a foil which is specifically made of polyvinyl-idene-fluoride or polyvinyl-fluoride or polyvinyl-chloride, and having an area, being at least as large as the cross-sectional area of the radiation that leaves the measuring and gas containing chamber; a measuring signal is extracted from the foil. The foil is preferably blackened and has a thickness between 6-10 micrometers.

Abstract: An apparatus and method for detecting gas concentration using an infrared absorption gas detector. Noise due to vibration is substantially reduced by integrating the voltage produced by the gas detector with an integrator having an adjustable time constant. The time constant is adjusted to a long value during times when the gas concentration is remaining relatively constant. When the gas concentration is changing substantially, the time constant is adjusted to a relatively short value to allow the output of the integrator to better follow the changes.

Abstract: An infrared analyzer where infrared radiation is passed through a measurement cell containing a material that includes a component that absorbs infrared radiation. The radiation exiting the measurement cell passes into a first detector, through an optical filter to a second infrared radiation detector. By analyzing the outputs from each detector and by knowing the characteristics of the optical filter, the concentration of certain infrared absorbing components in the material can be determined.

Abstract: The extinction coefficient of atmospheric aerosol is measured by an instrument in which a single light beam from a graybody source is alternately directed through two similar optical paths to a detector. Each optical path traverses an equal length region of ambient air. Aerosols are filtered from the ambient air region of one optical path .The detector measures the modulation of the incident radiation and its output is a function of the extinction coefficient of the ambient air under test. A second detector is used to monitor the beam power. Processing electronics compute the extinction coefficient of the ambient air under test from the detector outputs. The ambient air regions of the two beam paths are alternately filtered for improved performance.

Abstract: Spectroscopic measurements of stable isotopes are performed using a tunable lead salt diode laser. The design of the system is based upon the optimization of isotopic spectral lines from two different path lengths in an absorption cell using a single gaseous sample. A short path cell to measure the more abundant species and a long path cell to measure the less abundant species are used. A micrometer adjustment of a path length is used for equalizing spectral line intensities to obtain a measure of isotope enrichment or of absolute isotopic concentration.

Abstract: A infrared gas analyzer having measuring and reference chambers and receiving chambers respectively disposed on radiation exit sides of the measuring and reference chambers and being filled with a particular gas; a pressure communicating duct system including a particular chamber interconnects the two receiving chambers is partitioned by a foil of polyvinylidenfluoride being piezo electrically effective to generate an electrical signal on account of a pressure differential between the two receiving chambers, as indication of the concentration of the measuring gas, i.e., host gas that flows through the measuring chamber.

Abstract: Cell for gas analyzers, having a casing with a cylindrical bore which is divided by an axial wall of separation into two chambers. The one chamber serves for the gas being measured and the other for a reference medium. The chambers terminate in windows at both ends. To make such a cell resistant to pressure and corrosion, the reference medium is constituted by a transparent, glass-clear material which is disposed in the cylindrical bore. At each end of the cylindrical bore there is provided an annular shoulder for the support of an annular gasket and a window. The windows are held by annular compression flanges and annular gaskets.

Abstract: An amplifying circuit for amplifying an output from a measurement wavelength detector consists of a preamplifier and a measurement signal amplifier provided at an output of said preamplifier. The measurement signal amplifier is provided with an input-resistance and a feed-back resistance, a variable resistance connected in series to a normally open switch, the series combination being connected in parallel to the feed-back resistance so that the gain of the measurement signal amplifier may be variable.

Abstract: The method and apparatus permit analyses, by optical means, of properties of gaseous suspensions of particles, by measuring radiation that is emitted, transmitted or scattered by the particles. Determinations of composition, size, temperature and spectral emittance can be performed either in-situ or by sampling, and Fourier-transform infrared spectrometric techniques are most effectively used. Apparatus specifically adapted for performing radiation scattering analyses, and for collecting radiation from different sources, are provided.

Abstract: A selective infra-red detector is used to determine the amount of a selected gas present in a gas sample. A beam of infra-red energy is passed through a gas sample and into the selective infra-red detector. An outer annular portion of the beam is reflected from a paraboloidal mirror onto a first focal point, while an inner annular portion of the beam passes through a chamber containing a fluid which will absorb the spectral wavelengths of the selected gas and is reflected by a spherical mirror onto a second focal point. Separate infra-red energy detectors are positioned near the first and second focal points to measure the infra-red energy. The difference or ratio between the infra-red energy measured by each infra-red energy detector is a measure of the amount of selected gas present in the gas sample.

Abstract: An improved non-dispersive infrared analyzer. The analyzer includes an improved source assembly having a reflecting element with a concave annular reflecting surface, and a circular heating element which is located substantially at the focal region of the reflective surface. The analyzer also includes an improved detecting assembly having a reflecting element with a paraboloid reflective surface that focuses radiation on one or more detecting elements that are located out of the field of view of the reflecting element. Because of the better collimation and more efficient use of its infrared beam, analyzers which include these source and detecting assemblies may use sample cells having non-reflective inner surfaces, and thereby provide output signals of improved stability.

Abstract: A radiation beam, having passed through the mixture containing the component whose spectral composition contains at least one characteristic spectral line of the component, is caused to pass alternately along two channels one of which comprises a definite amount of the gaseous component and the other of which serves as reference. The second channel over which the radiation beam travels is limited to a diaphragm having a radiation transmission substantially equal to that of the first channel in the absence of said component in the mixture. The output beam from the two channels is directed towards a detector for detecting the variation of intensity of the beam through a filter for selecting said characteristic radiation.

Abstract: An optical multi-beam gas measuring apparatus is intended for detecting specific content in a gas of extraneous gases which absorb the same wavelength of the measuring radiation. The apparatus comprises a source of radiation and a gas vessel through which the gas mixture to be measured is conducted and the radiation is detected. The radiation directed through the vessel is picked up by an exchangeable detecting unit which contains a prism for splitting radiation which has passed through the gas mixture into several partial beams corresponding to the number of gas components to be measured. A prism is selected for this purpose and it is used in association with optical filters arranged in the path of the beams in conjunction with detectors which are electronically arranged for detecting the selected gases and measuring the value thereof.

Abstract: A gaseous sample and a reference volume are traversed by electromagnetic iation and the absorption caused by the sample, as given by the difference between the radiation intensities after passage through the sample and the reference volume, is measured and used as a measurement value.By means of radiation of a wavelength in the range between 3.8 and 4.15 .mu.m, the specific mass of particles characterized by broadband absorption--especially graphitic particles--is determined; by means of radiation of a frequency band centered in the wavelength range of 3.35 to 3.5 .mu.m, whose 3 dB bandwidth does not exceed 0.3 .mu.m, the specific total mass of aerosol particles is determined, and by the additional measurement of the resonance absorption at a wavelength in the range of 3.35 to 3.5 .mu.m the percentages of both graphitic and organically soluble particles are determined separately.

Abstract: An improved detector for combustible gases and which is able to discriminate between natural gas (methane and ethane) and other sources of methane (e.g. swamp gas, petrochemical and automotive) or other combustible gases by measuring the characteristic methane/ethane ratio of natural gas, based on infrared absorption of methane and ethane, in combination with another non-specific combustible gas detector.

Abstract: A nondispersive, two-beam, infrared gas analyzer with two differently long measuring gas cells and differential detectors is improved by gilt detection cell interiors and absorbing rods in the detector cell which is in line with the shorter measuring gas cell. Adjustable absorption permits suppression of cross sensitivity errors.

Abstract: A measuring device for measuring the concentration of particles in a liquid advanced through a tube (2) includes a transducer where the tube in a measuring zone has an area change implemented such that the pipe wall is kept clean from deposits. Probes (8, 9) are inserted in the tube wall (6, 7) so that the measuring surfaces of the probes are in contact with the liquid and form a part of the tube wall. The measuring device is compensated for temperature by means of a reference apparatus (13, 14) coacting with said probes electrically and mechanically.

Abstract: A photometric detection method and apparatus employ a variable beam modulation device, such as a planar oscillating disk whose reflectance and transmittance with respect an incident beam of electromagnetic radiation vary with disk angular position, to form, from an incident beam of radiation, two amplitude modulated correlated component beams. Preferably the amplitudes of the component beams vary sinusoidally, 180.degree. out of phase. In one illustrative embodiment, one of the component beams passes through a sample fluid, which absorbs a portion of the radiation at a wavelength characteristic of a selected component. The second component beam passes through a reference path and provides a reference signal relative to which changes in the sample fluid are measured. A feedback mechanism is provided to automatically adjust for variations which can occur while the apparatus is operating.

Abstract: An infrared gas analyzer for measuring at least one component gas of a sample gas mixture. A beam of infrared radiation is periodically interrupted and propagated through a measuring cell through which the sample gas mixture flows. The infrared radiation beam is divided into a reference ray which is propagated through the measuring cell, and a selectivity cell which contains the component gas to be measured; and a measuring ray which is propagated through the measuring cell, and a gas-filled compensation cell. In one embodiment, the compensation cell and the measuring cell are serially coupled to one another so that the sample gas mixture flows through both. Alternatively, the compensation and measuring cells may be connected in parallel with respect to one another. Selective detectors are provided for producing an output signal responsive to the difference between the attenuation of the measuring ray and the attenuation of the reference ray, as they are propagated through their respective paths.

Abstract: An amplifier, responsive to a photosensitive element operating in a high intensity ambient level, and a method for selecting circuit parameters of the amplifier, take into account differing dynamic mechanisms to provide an optimum tradeoff between signal and noise. The dynamic mechanisms, manifested as electrical noise, affect and are particularly noticeable in the output of the photosensitive element operating in a high energy level environment. The method provides steps for selecting an optimum circuit element for enabling a receiving apparatus to achieve a superior signal to noise figure and hence superior sensitivity to a small AC signal level "riding" on a high DC ambient signal.

Abstract: By the use of one or more beams of chopped, variable-frequency, monochromatic light to illuminate the sample chamber of at least one gas-filled cell including such sample chamber and a reference chamber joined to the sample chamber by a tunnel-like opening or orifice which permits fluid communication between the chambers and incorporating a thermal-flowmeter-type sensor element in the path of flow of the fluid between the chambers of each such cell, the compositional characteristics of one or more samples in each sample chamber can be determined accurately.

Abstract: Near real time remote sensing of atmospheric gases is performed using differential absorption lidar or transmission techniques. The wedge absorption remote sensor (WARS) utilizes an emission spike train of short time duration as is found in the long pulse output mode of a solid-state laser to define the on and off line absorption of an atmospheric gas and hence its concentration. The laser beam is split into a reference beam and a transmission beam which passes through the atmosphere being tested. The two beams are detected and amplified, and them digitized. Comparing the ratio of the digitized reference signal to transmitted signal for each spike in the spike train yields a set of transmittance values as a function of wavelength. When the digitized reference and transmitted signals are plotted, a wedge of data points results. The ratio of the upper and lower slopes of the wedge yields the absorption coefficient and concentration of the absorbing gas.

Abstract: A method and apparatus are described for determining the partial pressure of carbon dioxide in the arterial blood of a patient. The method and apparatus are particularly useful where the patient is under anesthesia. Carbon dioxide concentration is measured at the end tidal of the patient's exhaled breath. Nitrous oxide concentration is also measured so that the measured values of the carbon dioxide concentration may be corrected in accordance with the measured value of the nitrous oxide concentration. Particular wavelengths of detection are described, together with other apparatus parameters to provide a high level of accuracy.

Abstract: A scanning spectrometer incorporating a scanning diode laser powered with a controllable injection current. The injection current control may be set at predetermined discrete levels. These levels may be varied in accordance with signals derived from a servo loop, and may have superimposed upon them a cyclically varying substantially constant amplitude current. The laser output is directed via a beam splitter to both sample and reference cells. The material in the reference cell is so selected as to provide absorption features at each of the desired frequencies. The cyclically varying current is provided with an amplitude sufficient to cause a frequency amplitude at least as great as the maximum breadth of each of these spectral features of interest. The preselected bias currents are selected so as to provide lasing action of the diode at or near each of the selected frequencies.

Abstract: A cuvette for optical gas-analysis apparatus, having an elongated metallic housing with two end-faces, two chambers which are parallel to the longitudinal axis and have radiation-reflecting wall surfaces and which are separated from each other by a partition. One of the chambers is for holding a gas under investigation and the other is for holding a reference gas. The chambers are closed off at the end-faces of the housing by radiation-penetrable windows made of a material from the group consisting of calcium fluoride and barium fluoride and which are each initially connected by glass solder to an intermediate frame, which is connected to the housing. The intermediate frame has a U-shaped cross-section and is composed of a metal from the group consisting of gold, silver and aluminum and the intermediate frame is connected, to the windows and to the housing by glass solder.

Abstract: An apparatus for measuring vapor density and saturation ratio of individual chemical species in multi-component, multi-phase systems includes means to permit measurement in supersaturated vapor and in the presence of liquid, solid and dispersed aerosol phases of the sampled gas component and of other chemical species. Active narrowband differential measurements of broad band radiation passed through the sampled environment and then isolated to a plurality of narrow wavelength bands whose wavelength is related to the gaseous absorption spectra of the sampled species permit the measurement of vapor density of individual chemical components. A concurrent passive radiometric measurement of gas temperature in a strong absorption band of a relatively constant gaseous component enables the conversion of component vapor density to component saturation ratio even in the presence of component or system supersaturation.

Abstract: A photometric detection method and apparatus employ a variable beam modulation device, such as a planar rotating disk whose reflectance and transmittance with respect an incident beam of electromagnetic radiation vary with disk angular position, to form, from an incident beam of radiation, two amplitude modulated correlated component beams. Preferably the amplitudes of the component beams vary sinusoidally, 180.degree. out of phase. In one embodiment, one of the component beams passes through a sample fluid, which absorbs a portion of the radiation at a wavelength characteristic of a selected component. The second component beam passes through a reference path and provides a reference relative to which changes in the sample fluid are measured. The component beams are combined and are directed onto a detector which produces an output proportional to the intensity of the combined beam.

Abstract: A gas analyzer for performing gas analysis on a sample gas containing contaminants which normally interfere with the operation of the analyzer is disclosed comprising a source of radiant energy; means for directing radiant energy through a sample gas; a disposable gas cell; a detector for receiving radiant energy; and a circuit for analyzing the output of the detector and indicating the concentration of predetermined constituents in the sample gas. The gas cell comprises a disposable sample gas cell having a sample enclosure for containing a sample gas volume; sample windows defining a portion of a sample gas optical path extending from the source of radiant energy through the sample gas volume to the detector; an inlet for supplying sample gas to the sample gas volume and an outlet for exhausting sample gas from the sample gas volume.

Abstract: A method and apparatus is disclosed for selectively determining by non-dispersive infrared techniques the concentration of a gaseous constituent in a sample gas mixture while determining and discounting deleterious effects of spectrally interfering gases in the sample gas mixture.

Abstract: An infrared type gas analyzer having measuring and reference cells is equipped with alternately switchable valves so that the cells can alternate acting as the measuring and reference cells. The output of the detector is stored for each configuration and these outputs are subtracted from one another to provide the output of the analyzer.

Abstract: Spectroscopic measurements of stable isotopes are performed using a tunable lead salt diode laser. The design of the system is based upon the optimization of isotopic spectral lines from two different path lengths in an absorption cell using a single gaseous sample. A short path cell to measure the more abundant species and a long path cell to measure the less abundant species are used. A micrometer adjustment of a path length is used for equalizing spectral line intensities to obtain a measure of isotope enrichment or of absolute isotopic concentration.