Abstract: A photo expansion gas detector includes a radiation emitter, a sample gas, an expansion gas hermetically sealed in a chamber, and a capacitive diaphragm for sensing pressure changes. The radiation emitter may be constant or may be cycled on and off. Radiation passes through the sample and into the expansion gas. The expansion gas expands according to the intensity of the radiation received. The capacitive diaphragm is impacted directly by the expansion gas. The capacitive diaphragm deflects relative to a fixed capacitive plate, resulting in changes in capacitance representing expansion and contraction of the expansion gas. The electrical signal generated by the changes in capacitance represent changes in the gas composition of the sample. The electrical signals are then processed to activate control systems.

Abstract: In a plastic identifying apparatus (1), a reference light (L1) and a detecting light (L2), each having a predetermined wavelength, are irradiated to an object to be identified (4), and the transmitted lights of the reference light (L1) and detecting light (L2) are received. A detecting value expressing the quantity of light received of the detecting light (L2) is divided by a reference value expressing the quantity of light received of the reference light (L1), to obtain a computed value, based on which performed is identification of plastic forming the object to be identified 4. The wavelength of the reference light (L1) is in a wavelength band (hereat, 1550 nm) in which the light absorptances of all the types of plastics are of the lowest level, and the wavelength of the detecting light (L2) is in a wavelength region (hereat, in the range of 1700 to 1760 run) in which the absorption wavelength bands of many plastics except for PET, such as HDPE, are present.

Abstract: A fluidization level sensor and controller for use in a fluidized patient support surface has a controller coupled to a sensor and a compressor. The patient support surface contains a mass of granular particles housed in frame walls and supported by a diffuser. The compressor forces a fluid, typically air, into a plenum chamber and through the diffuser. The fluid flows through the mass of granular particles, causing the mass of granular particles to fluidize, and exits through a fluid permeable sheet. The fluidization level sensor produces an output signal proportional to the fluidization level of the mass of granular particles, and provides this output signal to the controller. The controller generates a compressor control signal in response to the output of fluidization level sensor, which in turn adjusts the compressor to maintain a substantially constant fluidization level.

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: An on-line method for detecting particle size of a liquid during a process in which there is not a correlation between low absorbance with small particle size, the method comprises the steps of measuring a plurality of reference particle sizes each associated with a particular near infrared diffuse reflectance spectrum for creating a reference infrared diffuse reflectance spectrum having high absorbance with small particle size; measuring on-line a near infrared diffuse reflectance spectrum of the liquid during the process; and determining the particle size of the on-line liquid based on correlating the on-line-measured particle size with the reference near infrared diffuse reflectance spectrum.

Abstract: The invention relates to a gas cell (1) adapted for carbon dioxide and including a cavity (10) which is adapted for a chosen gas volume, a light source (11) and a light-bundle receiving unit (12). The light source (11) is placed in a focal point (F) associated with a partially elliptical mirror surface (13) forming a reflector for the light source (11) and a first defining surface of the cavity (10). Two other cavity-defining surfaces are comprised of gas-conducting surfaces (14a, 14b) orientated from the end-parts (13a′, 13b′) of the mirror surfaces (13a, 13b). The light-bundle receiving unit (12) is placed in a second focal point (F′) associated with the partially elliptical mirror surfaces (13a, 13b).

Abstract: A method for monitoring the high temperature reducing combustion atmosphere in a combustion process is disclosed. First, a spectral region for monitoring CO and H2O is identified. A laser wavelength is scanned so that a complete absorption transition includes a portion of the baseline. A laser is then referenced to an ITU-GRID. An output signal is generated from the laser and directed to a coupler to split the output signal in a predetermined ratio to a first component and a second component. The first component is directed to optics where it is shaped and collimated and then directed across a sample to be monitored to a detector that generates a measured output. The second component is directed to an absorption measurement device. The measured output is compared with the second component, and the temperature of the atmosphere and the concentration of the CO present in the atmosphere is calculated.

Abstract: The invention comprises a spectroscopic measuring device, a seal for such a device, and a method for sealing such a device. A window having a first and second portion is disposed in a cavity of a housing. The first portion is adjacent to an exterior of the device and has a first diameter less than a second diameter of the second portion, thus forming a shoulder therebetween and defining a gap between the first portion and an interior housing surface. An intermediate ring with a, metallic coating is disposed in the gap adjacent to the shoulder. A retaining ring is disposed in the gap adjacent to the intermediate ring. An exposed surface of the retaining ring is flush with an end housing surface and an exposed sapphire surface. A portion of the exposed retaining ring surface is electron beam welded to a portion of the end housing surface. The housing, intermediate ring, and retaining ring comprise a nickel-molybdenum-chromium alloy.

Abstract: A system and method employing infrared laser spectrography and dual wavelength modulation to monitor the concentration of a gas, such as oxygen or carbon dioxide, in the sample vial, or to monitor the pressure in the sample vial, to thus detect for microorganism growth in the sample vial. The system and method each employ an energy emitting device, such as an infrared laser, a detector and a signal analyzer, such as a spectroscopy device. The infrared laser emits toward the container infrared energy having a substantially single wavelength substantially equal to a wavelength at which the gas absorbs the infrared energy. The detector detects a portion of the energy signal that passes through the container, and the signal analyzer spectroscopically analyzes the detected portion of the energy signal to determine whether the gas exists in the container, or to determine the pressure in the container.

Abstract: A hemispherical detector comprising a plurality of photodetectors arranged in a substantially contiguous array, the array being substantially in the shape of a half-sphere, the half-sphere defining a closed end and an open end, the open end defining a substantially circular face. Also provided is a method for constructing a hemispherical detector comprising the steps of making a press mold of the desired shape of the hemispherical detector, pouring a material into the press mold to form a cast, finishing the cast to remove any defects, coating the cast with a coating material, and attaching a plurality of photodetectors to the cast.

Abstract: A multi-gas sensor is provided which modulates a polarized light beam over a broadband of wavelengths between two alternating orthogonal polarization components. The two orthogonal polarization components of the polarization modulated beam are directed along two distinct optical paths. At least one optical path contains one or more spectral discrimination elements, with each spectral discrimination element having spectral absorption features of one or more gases of interest being measured. The two optical paths then intersect, and one orthogonal component of the intersected components is transmitted and the other orthogonal component is reflected. The combined polarization modulated beam is partitioned into one or more smaller spectral regions of interest where one or more gases of interest has an absorption band.

Abstract: A rigid redundant light source for obtaining down hole near infrared data in a NIR data acquisition instrument is provided having a plurality of lamps positioned in close proximity and symmetrically about a common optical axis. A lens system for capturing and collimating the light is provided. The structure is arranged and dimensioned so that a single collimating lens can be used for a plurality of light sources. A switch and sensor is provided for turning on an alternate light source when a first light source burns out. A filter is rotated 90 degrees with respect to the light sources to minimized off axis error when switching between light sources.

Abstract: A method for detecting and measuring volatile components in expired gas by sampling the expired gas containing the volatile components; passing infrared radiation from an interferometer through the sample; detecting infrared radiation transmitted from the sample to produce a signal characteristic for the volatile components in the sample; and processing the signal and a set of single component reference library spectra of pure molecular gases in order to detect and calculate the amount of the volatile components in the blood of an individual expiring the gas, including the use of a low resolution FT-IR spectrometer in the detecting and processing.

Abstract: A procedure for the determination of the quality of gas of a probe gas, in particular a burnable gas, using a transmission spectrum of the probe gas determined at operating conditions by means of spectroscopical methods of measurement. At least the associated values of the pressure p and the temperature T of the probe gas are determined and in a number of selected spectral regions at least one spectral vector is constituted by integrating quantities of the transmission spectrum of the probe gas, which shows as components the values of the integrals with respect to the selected spectral regions and is characteristic for the properties of the probe gas at operating conditions.

Abstract: A method and apparatus for infrared gas analysis are provided. The method includes measuring a concentration of a component in the sample gas, and measuring a concentration of water in the sample gas. The component concentration measurement is corrected with respect to water interference at a zero point. The component concentration measurement is further corrected with respect to water influence in coexistence to determine a corrected measurement that is corrected with respect to water interference at the zero point and water influence in coexistence.

Abstract: A radiation source assembly and transducer incorporating same are suitable for use in measuring spectral absorption properties of a substance to be analyzed, such as a gas. The radiation source assembly has an optical axis. A measuring radiation source provides radiation in the direction of the axis and a reference radiation source provides radiation in the direction of the axis. An optical diffuser is spaced from the radiation sources along the axis. Radiation from the measuring radiation source and radiation from the reference radiation source are applied to the diffuser and the diffuser forms an exiting radiation beam for the assembly from the radiation of the measuring radiation source and reference radiation source. The exiting radiation beam extends along the axis.

Abstract: A gas stream monitoring system including a low cost main stream gas analyzer system is disclosed herein. The low cost main stream gas analyzer system is calibrated by a side stream gas analyzer system included in the gas stream monitoring system. Once calibrated, the side stream system is placed into standby mode such that diversions of portions of the gas stream can be minimized. The calibrated output signals from the low cost main stream system contain corrections for gas interference, pressure change, temperature change, manufacturing tolerance, component flaws, and any other sources of error.

Abstract: A hemispherical detector comprising a plurality of photodetectors arranged in a substantially contiguous array, the array being substantially in the shape of a half-sphere, the half-sphere defining a closed end and an open end, the open end defining a substantially circular face. Also provided is a method for constructing a hemispherical detector comprising the steps of making a press mold of the desired shape of the hemispherical detector, pouring a material into the press mold to form a cast, finishing the cast to remove any defects, coating the cast with a coating material, and attaching a plurality of photodetectors to the cast.

Abstract: An analog detection system for determining a ring-down rate or decay rate 1/&tgr; of an exponentially decaying ring-down beam issuing from a lifetime or ring-down cavity during a ring-down phase. Alternatively, the analog detection system determines a build-up rate of an exponentially growing beam issuing from the cavity during a ring-up phase. The analog system can be employed in continuous wave cavity ring-down spectroscopy (CW CRDS) and pulsed CRDS (P CRDS) arrangements utilizing any type of ring-down cavity including ring-cavities and linear cavities.

Abstract: A multi-component analyzing apparatus for measuring a concentration ratio of gas components of fron gas is provided, while the fron gas is constituted by several sorts of single gas components of fron gas, and the fron gas is employed as a measuring subject sample made by mixing a plurality of measuring subject components with each other, whose sort and quantity are limited.

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 and device for the continuous real-time monitoring of relative blood volume change, based on registration of blood hemoglobin concentration, during long periods of time, such as dialysis session. A method and device for cardiac output measurement, based on optical dilution technique, during dialysis, surgeries, intensive care procedure. The effects of blood electrolyte composition change which result in a change of light beam geometry are eliminated by the relative orientation between a light source and a single light or photodetector. An illumination axis and a detection axis are oriented in an offset, non collinear configuration at a sufficient angle to substantially eliminate the scattering properties of the blood. A primary implementation of the device is extracorporeal paths, such as hemodialysis tubing systems, artery-vein extracorporeal artificial shunts, other extracorporeal systems. It also may be applied to vessels, tissues or to body parts being capable of transillumination.

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: A concentration detection system with a radiation source device which outputs a collimated beam of radiation across a sample path having an unknown concentration of fluid of interest and a detector device including a sample sensor, a reference sensor, and an integrating lens positioned to integrate the collimated radiation passing through the sample path evenly over the sample sensor and the reference sensor so that the instantaneous fields of view of the sample sensor and the reference sensor are the same to equalize any obscurations effects thereof.

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 multi-component gas analyzer having cassette-type light path system includes at least a cassette having a light source system, a light path system, an optical folding system, and an infrared detecting system. The light source system has an infrared light source, and a reflector for providing a parallel infrared light beam. The light path system has a cassette, an optical absorption chamber and a set of concave mirrors. A vent hole set is provided having a plurality of vent holes enclosed by an O-ring for sealing the gas between the stacked-up cassettes. The optical absorption chamber includes a highly reflective coating film coated on the inner wall surface thereof that is employed for introducing the gases to be analyzed and provides a space for contact between the gases and the infrared light.

Abstract: A spectroscopic IR and UV-vis absorption remote exhaust emission monitoring system and sensing instrument for non-invasive, multicomponent analysis of the exhaust plume emitted by in-use vehicles. The concentration of CO, CO2, HC, NO, N2O, C2H2, NH3, SO2, Aromatic hydrocarbons, aldehydes, HONO, NO2, and dust, among others and in any combination there-of, in such a mixture can be determined in real-time, or via post-processing of stored spectral data. The sensor employs an IR and a UV-vis sources, and the physically offset, collimated beams traverse the probed air column, typically a roadway, a plurality of times, before returning to the instrument. Although the IR and UV-vis beams converge at the optics opposite the instrument, they are not coaxial and, thus, do not require an optical device (i.e., dichroic beam splitter) to separate them. The separate IR and UV-vis beams are focused on the slits of rapid spectrometers, where they are analyzed to yield wavelength-resolved spectra (i.e.

Abstract: The present invention relates to the infrared detection of hydrocarbon gases; infrared light from a source (10) is passed through a filter (12) to produce a beam (14) passing through a space (16), which can potentially contain hydrocarbon gases. The wavelength of the beam (14) contains a wavelength that is absorbed by hydrocarbon gases (sample wavelength) and a wavelength that is not absorbed by hydrocarbon gases (reference wavelength). The beam (14) falls on a detector that contains sensors (22, 24) that receive light that has passed through respective filters (18, 20). Sample filter (20) allows a single wavelength to be transmitted; reference filter (18) allows two wavelength bands to be transmitted, the bands having wavelengths located on either side of the sample wavelength in order to eliminate the effects of atmospheric conditions that are unconnected with hydrocarbon gases.

Abstract: Method and system for cavity ring down spectroscopic analysis of non-cavity-filling sample. An interface of a sample (gas, liquid, thin film, bulk solid, etc.) is positioned at a Brewster angle relative to a p-wave polarized light beam propagating in an optical cavity so that substantially no light beam energy is lost by reflection at the interface. The light beam cycles one or more times in the cavity for each of a sequence of selected wavelengths, is extracted from the cavity, and is analyzed to determine an absorption spectrum for the sample. The cavity, except for the sample region may be filled with a solid, optionally dielectrically active and optionally having an electrical field applied thereto to vary the solid's refractive index according to the light beam wavelength used.

Abstract: A gas sensor (10) exposed by diffusion to a gas flow and operable to measure the presence of a particular gas component of the gas flow. The sensor (10) comprises a base (20), a diffuser (34), a source (36), a detector (38), and a detection chamber (40). The diffuser (34) is interposed between the gas flow and the detection chamber (40). Thus, rather than directly exposing the source (36), detector (38), and other electronics to the full force of the gas flow, the gas is passed to and from the detection chamber (40) by diffusion. The source (36) radiates energy having a particular characteristic such that the energy is proportionally absorbed by the gas component. The detector (38) measures the presence of any unabsorbed energy and generates an output signal indicative thereof. The detection chamber (40) is coated with a material known to reflect the radiated energy.

Abstract: An apparatus for analyzing a spectrum includes an elongated source of light, a device for producing a spectrum of the light, a sample stage, and an array of photosensitive elements for detecting the spectrum and providing an output representative of an intensity of the spectrum as a function of wavelength. The sample stage is interposed between the elongated source and the spectrum-producing device. The light propagates along a length of the sample stage from the elongated source to the spectrum-producing device. The elongated source has a length greater than or equal to a length of the array.

Abstract: An improved method and apparatus for use in optical testing of concentration in samples has been developed. The apparatus restricts the solid angle of illumination and the solid angle of detection to eliminate a high proportion of the scattered radiation while allowing the ballistic radiation and the snake-like radiation to be transmitted. In samples which contain multiple scattering centers, this allows less correction for variations in effective pathlength and allows easier calibration of the apparatus. The use of polarized radiation as a means of minimizing scattered radiation in the sample is also disclosed.

Abstract: An infrared absorption spectrometer features an optical microcavity, and a waveguide that evanescently couples light into the microcavity. The optical resonance frequency of the microcavity is tuned to coincide with an atomic or molecular resonance frequency of a selected atom or molecule. In this way, light coupled into the microcavity will experience absorption in the presence of an atomic or molecular subtance. The absorption causes a measurable change in the evanescent light coupling into the microcavity. The detection sensitivity of the spectrometer is significantly increased, compared to prior art spectrometers, because of the high Q value of the microcavity and the ensuing long optical path lengths of the resonant modes traveling within the microcavity.

Abstract: A diffusion-type NDIR gas analyzer with an improved response time due to convection flow created by a temperature gradient between gas located within a waveguide and gas located within a diffusion pocket of space created between the waveguide and a semi-permeable membrane which surrounds the waveguide. The temperature gradient may be created by a thermally resistive radiation source that is not thermally isolated from the waveguide. The semi-permeable membrane is made of a hydrophobic material and has a thickness sufficient to provide its own structural integrity. The semi-permeable membrane can have a porosity less than approximately 50 &mgr;m and be comprised of ultra high molecular weight polyethylene or TEFLON®.

Abstract: An optical gas sensor has a compact design and without movable optical elements, with at least one radiation source (8), at least one measuring detector (9, 12) and a reference detector (11). The reflecting measuring cuvette is designed as an annular space (1) between a first, inner cylinder section (6) and a second, outer cylinder section (2) that is concentric thereto. The annular space (1) is limited by a cover element (5) and a bottom element (7) arranged at a spaced location therefrom in the direction of the longitudinal axis. The cover element (5) is permeable to the measuring gas. The bottom element (7) accommodates the radiation source (8).

Abstract: An infrared optical gas sensor is improved with respect to the quality of the measured signal. The infrared radiation detectors (4, 6) used as the reference radiation and measuring radiation detectors include thin layers of a partially transparent material, which sends an electric measured signal that depends on the radiation intensity received. The infrared radiation detectors are arranged stacked one over the other and with an interposed narrow-band filter (3, 5) each, which are transparent at the measuring wavelength. The infrared radiation detectors have an electrically conductive coating on the top side and the underside and are contacted.

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: A method of camouflaging an object emitting infrared radiation by absorbing radiation or by altering its emissive pattern reduces its viewability by an infrared detector. An infrared radiation absorbing and/or altering layer containing microcapsules (10) is positioned proximate the infrared radiation source. The radiation is absorbed by means of a phase change material or plastic crystals. Concentrations and/or phase change materials are varied to enhance camouflage.

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: A multiple-gain, hand-held, near-infrared grain analyzer analyzes, e.g., protein content of grain by infrared transmittance and interactance (transflectance) has at least two gain values. A first gain value is used when calibrating the analyzer with an empty analysis chamber (empty except for the presence of air), and a second, higher gain value is used when analyzing grain samples.

Abstract: A process for determination of blackening of a lamp in which the blackening of a lamp can be determined without visual inspection in real time or during operation is achieved by the spectral radiant energy which is emitted by the lamp bulb being measured and evaluated based on the difference that exists between when blackening occurs as compared to when blackening does not occur. Therefore, blackening of a lamp can be determined by determining the change of the spectral radiant energy emitted by the bulb. Furthermore, in a lamp in which the bulb temperature changes, the spectral radiant energy emitted by the bulb can be measured at two different wavelengths and blackening of the lamp can be determined based on the change of the ratio relative to each other.

Abstract: A method and apparatus for determining the composition of an effluent stream from a vacuum processing chamber. A cell placed in the effluent stream from the vacuum processing chamber creates a glow discharge from the constituents in the effluent stream. An optical detector measures a particular wavelength corresponding to the presence of a particular species. In one embodiment the output from the optical detector is used to determine the endpoint of a chamber cleaning process.

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: Changes in the concentration of a chemical, such as a gas, are determined using a non-linear chemical sensor which is subject to shifts in calibration over time. In order to minimize errors caused by such shifts in calibration a first infrared signal (Ig(1)) is measured and using an absorption value under an assumed chemical concentration (C(1)), a zero chemical signal Io(1) is calculated using the known physical law and mathematical relation Absorption=1−Ig/Io. A second infrared signal (Ig(2)) is then measured and the absorption value is calculated using the previously calculated zero chemical signal. A second concentration (C(2)) is then determined and the change in concentration is calculated by subtracting C(2) from C(1).

Abstract: A method of stabilizing temperature effects on a gas analyzer includes transmitting infrared energy through a plurality of cells in a reference cell drum to a sensor in the gas analyzer. The plurality of cells include at least one cell containing a reference gas and at least one cell containing an air reference. The method also includes interposing a filter in at least one of the plurality of cells in the reference cell drum, wherein energy from the infrared beam is reduced. The method further includes rotating the reference cell drum such that the infrared energy fully passes through each of the plurality of cells for a limited period of time such that the sensor generates a substantial sine wave signal.

Abstract: A method and apparatus for demodulating a plurality of frequency components output from a photodetector in a wavelength modulation spectroscopy system and determining absorption line shapes from the demodulated data. Demodulation is performed with a homodyne demodulator. Line center magnitudes of selected even harmonics of the demodulated output frequency components are measured and the absorption line shape is calculated from the relationship between these magnitudes.

Abstract: Disclosed are a method and apparatus for dual modulation of an optical spectroscopy laser. Demodulation is accomplished in a manner resulting in measurement of absorbance of a gas species, as well as stabilization of laser wavelength and baseline noise reduction.

Abstract: A portable system for the real time detection and measurement of one or several gases is a gaseous mixture is disclosed. Such systems can be applied to industrial domains in which gases are to be measured and particularly toxic, dangerous, or polluting gases are generated. The system uses absorption spectrometry of a gas from a gaseous medium of interest. The optical means is at least two laser diodes with matchable cavities to generate a first and second wavelength, a light beam mixer prism, a double refraction crystal rotating on a controlled table. The tuned beam causes the gas to be measured to fluoresce and emit a signal to an infrared radiation detector which can indicate the identity and magnitude of the gas being measured.

Abstract: A miniaturized photoacoustic spectrometer made from a series of stacked substrates. An infrared source is formed in a first substrate. A filter is formed in a second substrate. A micro-trough is machined in a third substrate and a microphone is formed in a fourth substrate. A fifth substrate has a metallic deposit for reflecting light emitted by the infrared source. Resin sealing is provided between the substrates.

Abstract: Using at least one surface mount resistor as an infrared light emitter in an analytical instrument provides low cost, long life and high reliability.