Abstract: An example apparatus includes: a semiconductor substrate; a mechanical resonator supported by the substrate, the mechanical resonator including an array of capacitors; and a plasmonic infrared (IR) absorber including an array of metal structures. The mechanical resonator is between the substrate and the IR absorber.

Abstract: A spectrometry device includes a switch and a converter. The switch acquires a first reception signal and a second reception signal that respectively include information relating to an optical spectrum and switches between outputting the first reception signal and outputting the second reception signal based on control by a controller. The converter converts the first reception signal or the second reception signal output from the switch into a digital signal.

Abstract: A method for providing a calibration test gas sample includes identifying a first test canister containing a standard test gas including an ionic gas. A chemical formulation of the standard test gas includes a cation and an anion. The method further includes replacing the first test canister with a second test canister containing an improved test gas. A chemical formulation of the improved test gas includes a replacement atom comprising one of a heavier isotope of one of the cation and the anion.

Abstract: A particle detector, e.g. a smoke detector is described. In one form the detector includes a detection chamber and radiation source emitting a single beam of radiation. The detector also includes a radiation receiving system and an imaging system arranged to receive radiation from a common region of interest. Methods and systems for analyzing the output of a particle detector are also disclosed.

Abstract: The present application is directed an optical gyroscope. The optical gyroscope includes a substrate including a first and a second waveguide disposed thereon. One or both of the waveguides may be doped with a rare-earth material. A crossing element is disposed between the first and the second waveguides to form a substantially orthogonal connection therebetween. The application is also directed to a system including an optical gyroscope. The application is further directed to a method of observing characteristics of the optical gyroscope.

Abstract: A glucose sensor comprising an optical energy source having an emitter with an emission pattern; a first polarizer intersecting the emission pattern; a second polarizer spaced a distance from the first polarizer and intersecting the emission pattern, the second polarizer rotated relative to the first polarizer by a first rotational amount ?; a first optical detector intersecting the emission pattern; a second optical detector positioned proximal to the second polarizer, the first polarizer and the second polarizer being positioned between the optical energy source and the second optical detector, the second optical detector intersecting the emission pattern; a compensating circuit coupled to the second optical detector; and a subtractor circuit coupled to the compensating circuit and the first optical detector.

Abstract: A device and method for testing a fibre-composite component, which is to be processed by means of bonding, for the presence of at least one substance out of a selection of possible contaminants. A surface heating device for regional heating of a part-zone of the fibre-composite component to be bonded is performed for desorption of contaminants. A sensor array with a plurality of sensors detects contaminants in the gas phase, and a control device ascertains and signals contaminations which are found. An extractor device can be employed to extract machining dust from the fibre-composite component to a desorption device.

Abstract: A method for controlling an electronic device includes providing a display screen and a sensing assembly including at least one photoreceiver and phototransmitters. Emission of infrared light by the phototransmitters is controlled as an object moves in a first specified pattern of movement and then moves in a second specified pattern of movement, and measured signals are generated. The measured signals are evaluated to identify the first specified pattern, to detect a reference offset location, and to determine, for each of a group of time periods when the object is moving in the second specified pattern, a corresponding location of the object during that period. A centering operation is performed in response to the identification, wherein the centering operation moves an indicator to an initial predetermined reference location on the display screen; and sequential locations of the indicator are controlled in accordance with the corresponding determined locations.

Abstract: The invention relates to a method and to an apparatus for determining the adsorption of a gas at materials. It is the object of the invention to propose possibilities for the determining of the surface properties of materials in which statements can be obtained and very small sample volumes can be examined with sufficient measurement precision, with a reduced technical plant effort and with a reduced time effort. In the invention, a sample of a material is acted on by a gas or gas mixture within a chamber which is not transparent for electromagnetic radiation in the wavelength range between 150 nm and 25 ?m. The gas or at least a gas included in a gas mixture is adsorbed at the surface of the sample and in this respect the electromagnetic radiation emitted by the sample as a consequence of the adsorption is detected by at least one optical detector which is sensitive at least in a range of the wavelength range between 150 nm and 25 ?m.

Abstract: The present invention relates to optical sensor arrangements, especially sensors of the type that can be used in motor vehicles and which can detect hydrogen in a gaseous measured medium.

Abstract: A chemical vapor sensor is provided that passively measures a suspect chemical species of interest with high sensitivity and chemical specificity, for use with safety systems. A vapor concentrator amplifies a suspect chemical vapor concentration to a detectible level, for use with an infrared detector. Compensation is provided for environmental variations that may influence the passive measurement of the chemical vapor sensor. Environmental variations may include extrinsic vapors in the surrounding air, or air currents that divert the sample vapor as it drifts from the suspect vapor source to a sampling intake. In an example, ethanol vapor is measured and carbon dioxide tracer measurements are used to calculate an ethanol vapor measurement that is adjusted for environmental variations. In an aspect, a time artifact filter sets the output of the carbon dioxide sensor to match the time dependence of the ethanol sensor, to calculate blood alcohol concentration.

Abstract: A chemical vapor sensor is provided that passively measures a chemical species of interest with high sensitivity and chemical specificity. In an aspect, ethanol vapor in a vehicle cabin is measured, and sufficient sensitivity is provided to passively detect a motor vehicle driver that exceeds a legal limit of blood alcohol concentration (BAC), for use with vehicle safety systems. The sensor can be situated in an inconspicuous vehicle cabin location and operate independently without requiring active involvement by a driver. A vapor concentrator is utilized to amplify a sampled vapor concentration to a detectible level for use with an infrared (IR) detector. In an aspect, in comparison to conventional chemical sensors, the sensitivity of detection of ethanol vapor is increased by a factor of about 1,000. Further, a single channel of infrared detection is utilized avoiding spurious infrared absorption and making the chemical vapor sensor less costly to implement.

Abstract: A gas sensor of the type that detects the presence of a specific gas by monitoring the absorption of optical radiation transmitted through a chamber containing a sample of gas under test comprises an optical source for emitting radiation therefrom and a detector sensitive to radiation emitted from the source at opposing ends of a circumferential chamber, having optically reflective surfaces, extending around the periphery of a sensor housing. The optical pathway between the source and detector may include a radial portion, a circumferential portion and an axial portion to allow a compact optical path. The gas sensor includes, within a single housing, electronic circuitry for conditioning the electrical output of the detector to provide an output that is a function of at least one selected gas concentration and which is automatically compensated for at least one of temperature, pressure, humidity, and range normalization.

Abstract: An optoacoustic sensor for detecting one or more target gases includes a body featuring halves containing measurement cells. Each measurement cell is in communication with a light source and a microphone as well as the ambient atmosphere. Evaluation and control electronics are in communication with the light sources and the microphones sequentially illuminate the first and second light sources so that a measurement signal due to optoacoustic pressure variations from a target gas is generated by the microphone of the illuminated or gas active cell and a compensation signal is generated by the microphone of the non-illuminated or gas inactive cell. The compensation signal is subtracted from the measurement signal by the evaluation and control electronics to provide a sensor output signal.

Abstract: A geometric model comparator is provided, which includes processing circuitry, memory, and comparison circuitry. The processing circuitry is configured to generate a target model from a source model. The memory is configured to store the source model and the target model. The comparison circuitry is configured to identify selected points from the source model, create corresponding selected points in a target model, and compare the selected points from the source model with the selected points from the target model to identify one or more selected points from the target model that fall outside of a predetermined tolerance range with the respective one or more points from the source model. A method is also provided.

Abstract: It is an object to provide a photothermal conversion spectroscopic analysis method that enables measurement to be carried out with high sensitivity, and a photothermal conversion spectroscopic analysis apparatus that carries out the method. The photothermal conversion spectroscopic analysis apparatus is comprised of an exciting light source 111, a chopper 112 that is disposed close to the exciting light source 111 in the optical path of exciting light emitted from the exciting light source 111, a mirror 114 that changes the direction of travel of the exciting light, a detecting light source 120, a dichroic mirror 113 that has detecting light from the detecting light source 120 incident thereon and makes the exciting light and the detecting light coaxial, a lens 10 that has a suitable amount of chromatic aberration, and a holder 15 that holds the lens 10 such as to enable adjustment along three axes.

Abstract: A photometer for measuring gas components. The photometer has an infrared radiator with radiator modulation, a measuring cell with a measurement and comparison chamber, and a detector which absorbs optopneumatically onto the gas component X, that is filled with gas component X. In order in the case of a photometer of this type to render it possible for a plurality of gas components to be measured with high accuracy and the smallest possible outlay in apparatus, at least one further detector is arranged downstream of the first detector. For the purpose of measuring the gas component Y the further detector is filled with its isotope Y*, and the first detector is optically transparent with regard to the further gas component Y* to be measured or the characteristic absorption bands thereof.

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: A detector 1 for use in infrared gas analyzers has two compartments 14 and 15 to be filled with gas G showing the same absorption characteristics as the gas to be measured and which are arranged in series with a load cell 2, and the gas compartments 14 and 15 communicate with each other via a gas channel 16 in which a pyroelectric flow detector element 19 is provided.

Abstract: A microcomputer usable for a long period of time even when disposed in a high dose radiation-exposed environment, and its access speed control method are provided. According to the microcomputer and the method, the total dose of radiation that the microcomputer receives is determined on the basis of detection signals from a radiation detecting element. Based on the determined total dose of radiation, and table data preset by tests and stored into a memory unit, a CPU controls an access speed. Moreover, the CPU, and the memory unit and a circuit interface unit that access the CPU are integrated on a single chip (ASIC) These units on the same chip are deteriorated and changed in the same direction, without fail, on exposure to radiation.

Abstract: Photo acoustic infrared (IR) detector including a chamber for receiving a gas or gas mixture, a window for allowing pulsed or modulated IR radiation into the chamber, and a pressure sensor adapted to measure pressure changes in the chamber as a consequence of absorbed IR radiation. A generally plate-shaped main part has a recess or bore for substantially forming the chamber whereby the window closes the chamber at one side of the main part and whereby the pressure sensor is of the miniature type and is located at the opposite side of the main part in relation to said one side so that the pressure sensor communicates with and closes the chamber at the opposite side, except for a venting channel for the chamber. A cap is provided at said opposite side of the main part so that it encloses the pressure sensor and forms a gas space communicating with the chamber through the venting channel and being substantially larger than the gas volume in the chamber.

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: Thermoelectric sensor (12) formed by a membrane (14) including a plurality of thermoelectric elements (20) formed of a plurality of thermoelectric couples and forming a plurality of elementary cells. Each elementary cell is thermally insulated from adjacent elementary cells by metal wires (22, 23), preferably gold wires, arranged on the front face (25) of the membrane (14), more particularly, on an upper passivation layer (30). The metal wires (22 and 23) are thermally connected to a substrate (16) supporting said membrane. The two wires separating two adjacent thermoelectric elements (20) are separated from each other by an intermediate low thermal conduction region (28).

Abstract: An infrared type gas analyzer is formed of a measuring cell for receiving a gas to be measured; an infrared light source for irradiating the gas in the measuring cell; a correlation filter disposed adjacent to the measuring cell; and a sensor for detecting infrared light ejected from the infrared light source and passing through the correlation filter and the measuring cell to analyze the gas in the measuring cell. A correction filter is disposed on a portion of the correlation filter for correction or calibration of the gas analyzer. Thus, the infrared type gas analyzer has a simple structure and can perform a simplified correction without complicated operation.

Abstract: An apparatus for determining the alcohol concentration in a gas mixture, which may contain a number of such interference components that have substantial absorption within the range of the alcohol absorption line to be presently determined, by means of a method based on the absorption of infrared radiation. The apparatus comprises: a radiation source (1); a chamber (4) for receiving a gas mixture (6) to be measured, said chamber being provided with windows (7a, 7b) whereby a radiation (2) passes through the gas mixture; a detector (13) which receives the radiation having passed through the gas mixture and transforms it to an electric state for further processing; between the radiation source and the detector an optical interference filter (10), which has a narrow radiation transmission band and which is pivotable (P) relative to the main traveling direction of radiation for changing the wavelength range of the filter's transmission band.

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: A non-dispersive infrared analyzer and method for analyzing a concentration in a gas utilizes an infrared light source and a cell configured to have a gas flow therethrough. The cell also has an infrared light passage through which a sample gas stream and an infrared light beam can travel. A sector has at least two filters for filtering infrared light, and is provided with the apparatus. The sector alternately inserts the at least two filters into the infrared beam. A detector detects wavelengths of the infrared light beam which corresponds to an absorption band of the gas to be measured, and a second wavelength which corresponds to an absorption band of the preselected reference gas. The detector receives the infrared light beam after the light beam has traveled through the sample cell.

Abstract: A method and apparatus for adjusting the raw, instantaneous response of an NDIR and determining a linear response therefrom is disclosed. The NDIR detector cell is connected to an output which is adjusted according to the function (Ax)/(1-x) where the coefficient A is a constant for the NDIR being used, and x is the raw, instantaneous, response of the detector. The coefficient A is determined by assessing the maximum response of the NDIR with an infinite mass of analyte within the sample cell.

Abstract: A flame sensor comprises a cell (10) containing an infra-red absorptive fluid such as carbon dioxide gas. Heating caused by absorption of the infra-red radiation is detected by measuring a resulting temperature or pressure change.

Abstract: An apparatus for measuring the total content of organic carbon (TOC) and nitrogen (TN) in water. The TOC value is correctly determined as the sum of the liquid, dissolved, and solid substances of a specimen of the water. The apparatus includes a NDIR gas analyzer for simultaneously measuring the concentration of CO.sub.2 and NO gas components with a phase separator, a thermal reactor, a condenser, and two amplifiers for the pneumatic signals of the receivers with an indicator for the measured TOC and TN concentrations. The specimen is split into a gaseous part and a liquid part in the phase separator. The gaseous part which essentially contains the inorganic fraction of carbon, the TIC fraction, in the form of CO.sub.2 gas is cooled in a condenser until a substantial fraction of its water vapor content is separated in the condenser by condensation. The dried gaseous part is directed via the comparison vessels as comparison gas.

Abstract: A dual line of sight forward looking infrared (FLIR) navigation and targeting system including two separate infrared turrets housing respective optical gimbal assemblies which simultaneously provide two independently controlled lines of sight, one of which has wide field(s) of view for implementing a pilotage function and the other has narrow magnified field(s) of view for implementing a targeting function. Both lines of sight are merged following individual temperature compensating image gain and level adjusting operations in an optical multiplexer assembly, the output of which is coupled to a single IR detector in the form of a focal plane array having time delay integration. Two separate FLIR video image signals are generated in a single common processor, one for pilotage and one for targeting which can be viewed simultaneously and independently. The processor is also utilized and integrated with a radar system.

Abstract: Method and apparatus for measuring concentration of a solution use pathlength complementarily modulated cells comprising a sample cell and a reference cell arranged in parallel to each other and separated by a displacable separator window which is displaced parallelly in a direction of an optical axis of a measuring optical system thereby varying each of cell-length of sample and reference cells complementarily, detect transmitted intensities by the combined cells at different positions of the separator window while flowing a sample solution and a reference solution having a known concentration into the sample cell and reference cell, respectively, and calculate the concentration of the sample solution based on detected transmitted intensities, positions of the separator window at which transmitted intensities are detected and the known concentration of the reference solution.

Abstract: A pneumatic infrared ray detector for use in a gas analyzer provided with a gas-slowly leaking mechanism capable of not only controlling a quantity of gas leaked in high accuracy but also increasing a range capable of controlling said quantity of gas leaked is provided. A body is provided with gas chambers and a detecting gas chamber and the respective gas chambers are communicated with said detecting gas chamber through gas passages. A ring-shaped leak-controlling sheet on the bottom surface of the detecting gas chamber is provided with a groove-like gas-leaking passage between the inner and outer circumferential edges thereof and a ring-shaped diaphragm and a vibrating diaphragm are built up on said leak-controlling sheet to be fixedly pressurized by means of a cover plate through a pressurizing member and a plate spring.

Abstract: A pneumatic detector, non-dispersive infrared analyzer employing detector cell chambers in optical series. The invention having an auxiliary chamber communicating with the front chamber to increase the rear chamber's signal so as to balance the signals from the front and rear chambers. The use of xenon as a diluent gas in the detector chambers in combination with a mass flow detector to improve the sensitivity. The use of an improved synchronous detection method employing a voltage-to-frequency circuit to convert the detector signal to a synchronous high resolution digital signal. The use of an improved source electrically pulsed having low thermal mass and a large radiating area.

Abstract: The invention relates to a method for measuring of the total content of organic carbon and of nitrogen in water. The total organic carbon value is obtained correctly as the sum of the liquid, dissolved, and solid materials of a sample of the water. The device comprises a non-dispersive infrared (NDIR) gas analyzer for the simultaneous measurement of the concentration of the gas components carbon dioxide CO.sub.2 and nitrogen oxide NO. The NDIR gas analyzer includes a phase separator (50), a thermal reactor (52), a double cooler (70), two valves (54, 56), as well as two amplifiers (58, 60) for the pneumatic signals of the receiver detectors (30, 36) with a display (62. 64) for the measured concentrations, total organic carbon and total nitrogen. The sample is split in a phase separator (50) into a gaseous and into a liquid part. The gaseous part, which comprises substantially the inorganic part of the carbon, the total inorganic carbon part in the form of carbon dioxide CO.sub.

Abstract: Two gas-filled chambers (K1, K2) arranged one behind the other in the beam path, with frontal areas (F) transparent to the beam, are interconnected by a first line (L12) which contains a first pressure or flow rate sensor (SF1). A buffer space (P) is connected to one of the two chambers (K1) via a second line (L11) in which is arranged a second pressure or flow rate sensor (SF2). The output signals from both flow rate sensors (SF1, SF2) are taken via amplifiers (V1, V2) to a differentiator. The degree of amplification of at least one amplifier (V2) is tunable for equalizing. The field of application of the invention is in gas analyzers operating on the infrared absorption system.

Abstract: A method for measuring of the total content of organic carbon and of nitrogen in water. The total organic carbon value is obtained correctly as the sum of the liquid, dissolved, and solid materials of a sample of the water. The device comprises a non-dispersive infrared (NDIR) gas analyzer for the simultaneous measurement of the concentration of the gas components carbon dioxide CO.sub.2 and nitrogen oxide NO. The NDIR gas analyzer includes a phase separator (50), a thermal reactor (52), a double cooler (70), two valves (54, 56), as well as two amplifiers (58, 60) for the pneumatic signals of the receiver detectors (30, 36) with a display (62. 64) for the measured concentrations, total organic carbon and total nitrogen. The sample is split in a phase separator (50) into a gaseous and into a liquid part. The gaseous part, which comprises substantially the inorganic part of the carbon, the total inorganic carbon part in the form of carbon dioxide CO.sub.

Abstract: A process for spectroscopically measuring the content of a component in a liquid mixture involves passing a single optical beam through the mixture without the use of a reference beam and measuring the intensities of transmitted light in two different wavelength bands by means of two adjacent detectors responsive to light in the two wavelength bands respectively. The component being measured absorbs light within one of the wavelength bands. The ratio of the detector outputs can then be related to the component concentration. The principal use of the invention is for in-situ measurement of methanol in gasoline for motor vehicles.

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: Nondispersive infrared gas analyzer for the concurrent measurement in the concentration of several components contained in a gas sample, and including a source of and modulator for infrared radiation, a measuring and reference chamber are traversed by said beams, at least two serially pneumatic radiation detectors each having a front and a rear chamber filled with a respective component and each provided for measuring the pressure differential between the respective chambers, a filter disposed between the first detectors upstream and having opaque range which covers at least a major absorption band of the component filling the downstream detector but having a region of transparency which includes at least one secondary absorption band of that component.

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: 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 pneumatic detector for nondispersive infrared gas analyzers comprises two gas-filled chambers disposable one behind the colinearly with a source of infrared radiation and connected to one another by a gas conductive line containing a microflow sensor which generates an electrical signal indicative of the pressure difference between the two chambers. A third chamber is disposed on a side of the two chambers opposite the radiation source and is connected to a second of the two chambers via a gas conductive line. An adjustable aperture stop is arranged between the second and the third gas-filled chambers. The arrangement of chambers and the adjustable aperture stop serve to compensate and reduce to zero a negative cross-sensitivity.

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 infrared photometer having a measuring cuvette with entrance and exit windows and an output detector preferably made of polyvinylidenfluoride; a second infrared detector definitely made of polyvinylidenfluoride, being partially transmissive is disposed in front of the entrance window of the cuvette, and a selecting cuvette is insertible in front of this second detector.

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: A non-dispersive infrared analyzer for determining the concentration of two components of a sample fluid. A zero fluid and a sample fluid are alternately supplied to two cells. Two pneumatic detectors are respectively optically arranged in series with two light sources such that the two cells are respectively sandwiched between the two light sources and the two detectors. At least one filter whose passband corresponds to the absorbtion bands of one of the two components of the sample fluid is located directly adjacent to and optically in series with at least one of the two cells.

Abstract: A gas analyzer of the fluid modulation type includes at least one cell, structure for alternately introducing a sample gas to be analyzed and a reference gas into the cell, a detector for analyzing a property of the sample gas, and an arrangement for alternately discharging the sample gas and the reference gas from the cell. A critical flow device is located in the discharging arrangement. A pump is located in the discharging arrangement and has a capacity for operating the critical flow device under conditions of critical gas flow, thereby maintaining the gas passing through the critical flow device and the cell at a constant flow rate.

Abstract: The chopped infrared radiation leaving a measuring and sample gas chamber in an infrared gas analyzer is passed through and into two serially arranged detection chambers which are connected to a differential pressure chamber with capacitive pickup. The chambers are filled with gas of the type whose concentration, in the sample gas, is to be detected. One of the detector chambers contains a thin black wire, a diaphragm on the outside may shield an adjustable portion of that wire from radiation. The wire absorbs all radiation it intercepts and heats the environment.

Abstract: A relationship exists between the concentration of ethanol in human breath and blood. Ethanol absorbs infrared energy in the region of 3.46 mu. In this method the concentration of ethanol in breath is measured by collecting a sample in a chamber and passing through it a filtered, directional, and interrupted beam of infra-red energy at 3.46 mu. The path length is fixed. The exit energy falls on a tuned radiant energy detector. This beam is compared with a similar beam of radiant energy not capable of being absorbed by ethanol. The two signals are fed into a differential amplifier which activates a servo-system that moves a tapered radiant-energy absorbing medium in the path of one of the energy beams until a null condition is achieved. The distance the tapered medium must be moved to establish the null condition is measured by a potentiometer operably associated with it.