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.

Abstract: The present invention is a photo-acoustic leak detection system that detects whether gas is leaking from a component. The system includes multiple beams wherein one beam is not absorbed by the gas and is used as a baseline measurement, while another beam absorbs the gas and emits an increased signal. Upon contact with the gas, an acoustic sensor senses the reaction or lack thereof between the gas and the beams, thereby allowing a signal processor to receive the respective alternating sensor signals after which the processor calculates the difference between the first and second signals to determine whether a leak exists. The photo-acoustic leak detection system also includes a beam combining means which forces the multiple beams to enter an acousto-optic cell at the same location. The acousto-optic cell, in turn, which is controlled by a signal controlling apparatus, sequentially and alternately diffracts the multiple beams at the same predetermined angle.

Abstract: A method non-dispersive infrared (NDIR) gas analysis, which can be carried out by a gas analyser comprising a cell (10) containing of gas, a sender (30) of IR waves and at least a receiver (40) of such waves. The transmission of IR waves and/or the reception of IR waves after the passage of the gas occur directly in the cell (10) same wherein the gas is fed. The analyser has a body (11) defining the cell (10), a sender (30) of IR waves and at least a receiver (40) of such waves, that are located opposite to each other with respect to the cell (10). The IR sender (30) and the receiver (40) are both arranged in the cell (10) at its end (13,14). The body (11) has inlet (15) and outlet (16) channels for the gas and a cavity (17), which can be metal coated inside and that defines the optical path (80) for the IR waves.

Abstract: A low noise amplifier circuit modulates input signals at a frequency of about 1 kHz, subsequently demodulates and filters the signals to provide an analog DC output level in which the 1/f noise of the amplifier is effectively eliminated due to the selection of the modulation frequency above the significant level of 1/f noise. Its application in a preferred embodiment is in an NDIR system using a detector having a DC emitter employed with a thermopile detector to provide an analog varying DC low level signal.

Abstract: An integrated dual sensor package comprises a housing, a first sensor assembly and a second sensor assembly. The housing includes an internal vacuum chamber, a first window and a second window. The first window is transparent to a first wavelength of propagating energy and the second window is transparent to a second wavelength of propagating energy. The first sensor assembly and the second sensor assembly each have an active region responsive to a respective one of the first wavelength and second wavelength of propagating energy. The first sensor assembly and the second sensor assembly are each mounted within the vacuum chamber with the active region of each of the first sensor assembly and the second sensor assembly adjacently aligned with a respective one of said first window and said second window. The common alignment structure also serves as a common thermal interface to the external environment.

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 portable, infrared, multiple gas analyzer for measuring the concentration of a plurality of infrared absorbent gases with a simple optical arrangement for transmitting an infrared beam along an optical path along with gas mixtures to be analyzed. Light transmitting tubes arranged in a U-like configuration transmit infrared energy and the gases applied thereto over a small path to an infrared detector from an infrared source and provide electrical analog output signals representative of the detected gases. The detector output signals are processed by D.C. processing circuits including an analog to digital converter and microprocessing circuits for providing digital, binary coded, output signals representative of the detected gas concentration of the infrared absorbent gases. The analyzer can be readily calibrated by applying a non-infrared absorbent gas to the gas analyzer to provide a maximum output signal level with the infrared beam on and the background level or dark level signal with the beam off.

Abstract: A method of determining remote gas concentration values from remote gas sensors. The method is particularly applicable to heated metal oxide sensors; however, it is not restricted to this type of sensor. A polynomial fit is made of a sensor's gas response curve for each sensor in the system. Usually this is a third order polynomial; however, any other order can be used. The sensors response at zero concentration is a zero or root of the polynomial. This root is factored out of the polynomial reducing it one degree. It is possible to factor out more than one real root if such a root is known further reducing the order of the polynomial. The coefficients of the reduced polynomial are scaled and stored as absolute values in binary words at the remote. At least one additional word is used to store exponents and signs. These words are transmitted to a central location on demand so that the gas response curve can be recreated.

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

Abstract: For optical determination of ingredients of a pourable product by NIR spectroscopy, to attain replicable measurement results, the device provides that the product flows in the direction of gravity; that a valve is disposed in the conduit downstream of the measurement window and a controller is embodied to move the valve to its closed position at least for the duration of measurement. The method is distinguished in that the product flows in the direction of gravity pas a measurement site; is dammed up downstream of the measurement site in such a way that the flow comes to rest at the measurement site; is dammed up in the direction of gravity past a measurement site; is dammed up downstream of the measurement site in such a way that the flow comes to rest at the measurement site; and after the measurement, the product is removed from the stagnant segment.

Abstract: The invention relates to an optical measuring arrangement for measuring, particularly for liquid or gaseous substances (103). The measuring arrangement comprises at least one measuring head (104, 106) operating on an optical measuring band, and a measuring head holder (100) comprising a hole (108, 112) for fastening and supporting the measuring head (104, 106). In the hole, the holder (100) comprises an end piece (110) through which the measurement is to be made. On the optical band of the measuring head (104, 106), the end piece (110) is substantially transparent. Furthermore, the end piece (110) separates the measuring head from the substance (103) to be measured disposed in the measuring area (102).

Abstract: A transparent sheet 11 for transmitting an infrared ray therethrough is formed by laminating a PET sheet 5 on which a anti-fogging layer 4 can be formed easily and a PP sheet 12 with good infrared ray transmission property, thereby to make the thickness of the transparent window larger.

Abstract: Method and apparatus for detecting insect infestation within enclosed wall areas by detecting increased concentrations of a tell-tale gas. An intake nozzle is connected to an infrared gas analyzer by tubing and a pump. Ambient air in a room where an insect infestation in a wall is suspected is first sampled. A baseline gas reading is obtained. A small hole is made in the area of the wall where an insect infestation is suspected. The intake nozzle is placed within the hole and a second gas sample is taken. Concentration of the tell-tale gas in the second sample is compared to the concentration in the gas of the first ambient air sample. An increased concentration will ordinarily indicate presence of an insect infestation in the suspected area In most applications the tell-tale gas is CO2.

Abstract: Gases flow to individual gas analysis cells. The cells are sequentially aligned with an infrared detector, which senses the composition and quantities of the gas components. Each elongated cell is tapered inward toward the center from cell windows at the ends. Volume is reduced from a conventional cell, while permitting maximum interaction of gas with the light beam. Reduced volume and angulation of the cell inlets provide rapid purgings of the cell, providing shorter cycles between detections. For coal and other high molecular weight samples, from 50% to 100% oxygen is introduced to the tubes. Cells are suspended from adjustable holders on a frame which is spaced from a table. The table is moved by a linear motor and a fixed platen. Sides of the table are shielded to prevent electromagnetic and magnetic motor interference with detected results. The entire table, cells, mounting plate and linear motor are mounted in a housing with aligned holes for the analysis energy source and detector.

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 microns and be comprised of ultra high molecular weight polyethylene or Teflon®.

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: The present invention relates to an apparatus configured for identification of a material and method of identifying a material. One embodiment of the present invention provides an apparatus configured for identification of a material including a first region configured to receive a first sample and output a first spectrum responsive to exposure of the first sample to radiation; a signal generator configured to provide a reference signal having a reference frequency and a modulation signal having a modulation frequency; a modulator configured to selectively modulate the first spectrum using the modulation signal according to the reference frequency; a second region configured to receive a second sample and output a second spectrum responsive to exposure of the second sample to the first spectrum; and a detector configured to detect the second spectrum.

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 logging tool system for analyzing the carbon dioxide concentration in a fluid sample downhole in a borehole. A chamber is filled with the fluid sample and is closed to isolate the fluid sample from the borehole. The interior chamber volume is expanded to decompress the fluid sample, and a transmitter discharges light in the mid-infrared range. A sensor measures the absorbance of mid-infrared light by the decompressed fluid sample and generates a signal representing the carbon dioxide concentration. Mid-infrared light absorbance in the range between 4.1 and 4.4 microns can be analyzed by the processor to identify the carbon dioxide concentration in the fluid sample, and infrared absorbance in the mid-infrared range between 3.2 and 3.6 microns can be analyzed to identify methyl and metheylene components. A wiper cleans the transmitter and sensor between readings to reduce measurement errors caused by fluid sample contamination.

Abstract: When first and second PbSe detectors 6 and 7 are irradiated with intermittent infrared radiation from a light source 3, infrared radiation detection circuits 21a and 21b output electrical signals in accordance with the magnitude of the infrared radiation, respectively. The output signals are supplied as they are to a CPU 32 via A/D converter 31, and, on the other hand, AC signals of the output signals via AC components detection circuits 22a and 22b reach the CPU 32. The CPU 32 corrects the AC signals, based on data which relates to the resistances and sensitivities of the PbSe detectors 6 and 7 and which are stored in an EEPROM 23, and the DC components of the output signals of the infrared radiation detection circuits 21a and 21b.

Abstract: In this method of determining the concentration of a gas to be analyzed in a gas mixture, the value of a characteristic of the gas mixture having predetermined laws of variation as a function of temperature and of the gas concentration is calculated from at least one measured value of the intensity of at least one radiation transmitted through the mixture at ambient temperature, the value of the said characteristic at a reference temperature is determined from the law of variation of the characteristic as a function of temperature and the value of the gas concentration is determined from the law of variation of the said characteristic as a function of the concentration.

Abstract: A portable, infrared, multiple gas analyzer for measuring the concentration of a plurality of infrared absorbent gases with a simple optical arrangement for transmitting an infrared beam along an optical path along with gas mixtures to be analyzed. Light transmitting tubes arranged in a U-like configuration transmit infrared energy and the gases applied thereto over a small path to an infrared detector from an infrared source and provide electrical analog output signals representative of the detected gases. The detector output signals are processed by D.C. processing circuits including an analog to digital converter and microprocessing circuits for providing digital, binary coded, output signals representative of the detected gas concentration of the infrared absorbent gases. The analyzer can be readily calibrated by applying a non-infrared absorbent gas to the gas analyzer to provide a maximum output signal level with the infrared beam on and the background level or dark level signal with the beam off.

Abstract: A sensor assembly for monitoring process parameters in an adverse environment is disclosed. The sensor is mounted on an exterior side of a chamber for curing polymeric materials using radiation. A shutter on the sensor assembly separates a passageway in which a sensor element is disposed from the adverse environment. A gas source pressurizes the passageway so that the passageway has a positive pressure when the shutter is in an open position as well as a closed position. A mounting device mounts the sensor assembly to an inerting tube of the curing chamber so that the sensor element will sense radiation inside the chamber when the sensor assembly is mounted outside the chamber.

Abstract: In an infrared sensor including a compensating element and an infrared sensitive element, the main bodies of which consist of temperature-sensing layers of germanium and are supported on a single-crystal silicon substrate with bridge structures of silicon oxynitride layers; infrared protection layers individually made of aluminum and/or gold with a thickness of 0.1-1.0 &mgr;m formed on both sides of the main body of the compensating element via insulating layers of silicon oxynitride of about 0.1-10 &mgr;m for almost completely shielding the compensating element from incident infrared rays and improving the sensor's sensitivity.

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

Abstract: The present invention relates to an improved gas sampling device comprising a pair of hollow rectangular chambers having diffusion apertures, a heat insulating plate, a reflecting element, a light source and a light detector; wherein the pair of rectangular chambers are arranged one over the other, with the heat insulating element being placed therebetween, the reflecting element having two reflecting surfaces at right angle with respect to each other, one end of the rectangular chambers being secured to the reflecting element with each end thereof being aligned with a reflecting surface, the light source and the light detector being placed at the other end respectively of the rectangular chambers.

Abstract: A non-mechanical modulating device for use in infrared detection. The device is of particular use in the 8-14 &mgr;m range and has application in thermal imaging cameras and gas sensing systems. The modulator comprises a germanium element and a means of varying the carrier concentration. In particular, the variation of the hole concentration gives rise to the absorption of infrared radiation due to interband transitions between the light and heavy hole bands in the split valence band in germanium. The variation in hole concentration may be initiated in any convenient way, for example, by the irradiation of the germanium with visible or near infrared light, by the electrical injection of free carriers across a germanium diode structure or by electron impact on the germanium surface following acceleration under vacuum. In the case where the variation in carrier concentration is initiated by optical means, the surface of the germanium is treated so as to produce a low surface recombination velocity.

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: An electronic control for a grill, providing enhanced functionality and safety features. A hydrocarbon detector system provides an intermittently operated electro-optic device emitting photons at a wavelength which selective interacts with hydrocarbon as compared to air, associated with a detector for detecting the selective interaction and an alarm monitor for detecting an alarm state. A food temperature sensor is employed to proportionately control combustible fuel flow rate, to thereby control a food temperature profile. A communications network interface is provided to allow remote control and monitoring.

Abstract: Natural gas whose calorific value is to be determined is illuminated with a light beam that is applied by a measurement head and that defines three measurement bands with different wavelength ranges each having a bandwidth of 10 nm to 20 nm and all situated in the near infrared. The intensity of each light beam is measured after it has passed through the gas, and the calorific value of the natural gas is computed in situ and in real time on the basis of the optical absorption values obtained by measuring the intensities of the light beam after it has passed through the gas.

Abstract: An absorption spectroscopy device for determining the concentration of a gas (such as oxygen) in a sample cell includes a neutral density absorber or a quarter wave plate. Laser radiation from a laser diode passes through the neutral density absorber or the quarter wave plate, then passes through the sample cell, and then is incident upon a detector. In some embodiments, the laser diode is driven with a drive current having a stepped periodic waveform.

Abstract: A system and method are set forth for photoacoustical analysis of isotope and other compounds having telltale absorption wavelengths between 1700-2500 nm. The system and method includes a Co:Mg F.sub.2, optical parametric oscillator (OPO) or diode laser tunable between 1700-2500 nm which is directed into a sample at energies sufficient to generate detectable acoustical emissions. A microphone detects the emissions for processing and analysis. The system and method is adapted to detect stable isotope compounds such as .sup.13 CO.sub.2 as well as other chemical compounds. For non-gaseous compounds, a CO.sub.2 or diode laser is used to photoablate the baseous sample containing the suspected compounds.

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

Abstract: A gas volume concentration is determined. An electromagnetic radiation is emitted (state 1) through the gas volume. The radiation is filtered by temporally modulating the spectral transmission of said filter so as to obtain a temporal modulation of the energy of the radiation transmitted by the gas volume and this filter. This temporally modulated energy is detected and a signal E is extracted from it, the signal particularly depending on the concentration of the gas. The component Eac(1) of the time-variable signal and the component Edc(1) of the signal, which is not a time-variable signal are isolated. A radiation stops is emitted (state 0), and the component Eac(0) and the component Edc(0) of the signal received by the detector are isolated. The terms Eac(1)-Eac(0) and Edc(1)-Edc(0) are calculated, and the ratio (Eac(1)-Eac(0))/(Edc(1)-Edc(0)) is formed which then solely depends on the gas concentration c. From this, c is deduced.

Abstract: A gas detector, comprising a laser transmitter, a laser receiver, a gas reference cell formed of a sealed encircling wall defining an interior volume, a liquid partially filling the gas reference cell, a reference gas dissolved in the liquid and forming a vapor within the interior volume, at least a portion of the sealed encircling wall being transparent to electromagnetic radiation emitted by the laser transmitter to permit electromagnetic radiation to enter the gas reference cell, traverse a path through the vapor and exit the gas reference cell; and the laser transmitter, laser receiver and gas reference cell being coupled together with light guiding elements to form light paths that pass from the laser transmitter to the laser receiver through the gas reference cell and from the laser transmitter to the laser receiver through a target zone.

Abstract: An infrared gas analyzer is formed of a source of infrared rays for emitting infrared flux; an infrared flux interrupting device for chopping the emitted infrared flux from the source of the infrared rays; a condensing optical system for obtaining a predetermined solid angle in the emitted infrared flux to thereby form a condensed flux; and a multi-reflection cell disposed at an outlet of the condensing optical system, to which the condensed flux is supplied and a gas to be measured is fed. The multi-reflection cell has a multi-reflection optical system formed of a plurality of concave mirrors. The analyzer also includes an infrared level detector for detecting an amount of infrared rays with a wavelength band absorbed by a component gas to be analyzed and contained in the infrared rays emitted by the multi-reflection cell.

Abstract: An improved NDIR instrument as used for measuring the carbon dioxide content of a gas sample includes an electrically modulated incandescent lamp disposed at one end of a sample cell for containing the gas to be analyzed, and a first pyroelectric detector at the other end of the cell. The intensity of modulated radiation incident on the detector is measured using paired dual-slope integrators, each integrating the signal on alternate half-cycles of the signal provided by the detector, to determine the concentration of infrared-absorptive gas in the cell. At intervals, the cell is purged by an infrared-transparent gas, and a similar measurement made, allowing correction for long-term drift in the optical characteristics of the instrument.The instrument correctly determines the concentration of CO.sub.2 despite "leakage" of the broad-band infrared radiation emitted by the lamp through the sample to be analyzed.

Abstract: An interface for an in-line chromatograph mass spectrometer includes a mixing tee having a first inlet, a second inlet, and an outlet with the first inlet in fluid communication with the outlet of the chromatograph; a back pressure regulator having an inlet and an outlet with the inlet in fluid communication with the outlet of the mixing tee; a coaxial splitter having an inlet, a first outlet, and a second outlet, wherein the inlet of the coaxial splitter is in fluid communication with the outlet of the pressure regulator; a mass spectrometer having an inlet in fluid communication with the first outlet of the coaxial splitter. The interface regulates the flow into the spectrometer without undesirably increasing any back pressure to the chromatograph.

Abstract: An automatic no moving parts portable IR spectrometer for the purpose of analyzing automotive refrigerants comprising an IR source with intermittent output by electronic means not requiring an optical cavity or mechanical chopper, a gas cell which is activated via a one touch bellows to initiate a pressure switch triggering the analysis process, said gas cell followed by a non-imaging optical element which diverts the IR energy to a filter and detector equipped with a readout device to show analysis results.

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: The present invention is a system for controlling the power level of a beam exiting an acousto-optic cell and/or a beam delivery device. A beam detector senses the power level of the beam and produces a power signal indicative thereof. An error detector compares the power signal to a predetermined power level. If the power signal and predetermined power level differ, the error amplifier emits a correction signal to a variable amplitude source, which adjusts the amplitude of the acoustic drive frequency such that the power level of the beam exiting the acousto-optic cell and/or the beam delivery device is substantially equal to the predetermined power level.

Abstract: A system and method for determining the concentration of an analyte such as oxygen in an unknown gas sample. A Vertical Cavity Surface Emitting Laser (VCSEL) is used as a variable wavelength light source which is "swept" through a wavelength range by varying the drive signal applied thereto. Quantitative spectroscopic analysis of the unknown gas sample is performed without the requirement of feedback circuitry for tuning the light source to the characteristic frequency of an analyte. Instead, the VCSEL is repeatedly "swept" through a range of frequencies determined by the drive signal, and the absorption is measured by the detector. The absorption lines do not always occur at the same place but instead move along around during the sweep based on the temperature and baseline current. The absorption at a particular wavelength may be determined by overlaying the drive signal and its timing information over the detected absorption signal.

Abstract: Carbon Monoxide (CO) is a colorless, tasteless, and odorless gas which causes asphyxiation by combining with a strong affinity to blood hemoglobin. Unless a patient is quickly identified as having CO poisoning, the patient could face severe medical consequences including death.This patent describes a reagentless optical method for measuring carboxyhemoglobin (HbCO) in a whole undiluted blood sample that can be obtained from a fingerstick. A battery-operated triple wavelength device measures light transmission at frequencies of 548 nm, 810 nm and 950 nm through a 40 .mu.L sample of undiluted whole blood placed in standard disposable glass capillary tube. Having a portable point-of-care device, for uses by paramedics during an emergency situation, in the emergency room, or in a physician's office, can provide accurate immediate confirmation of CO poisoning.

Abstract: An infrared measuring arrangement with essentially expanded measuring range with an infrared radiation source (3) and an infrared radiation detector (4). The infrared radiation source (3) has a first, direct beam path to the infrared radiation detector (4), on the one hand, and, on the other hand, a second, reflected beam path to the infrared radiation detector (4), which is longer than the first one.

Abstract: A gas sensor (10) is shown having alternately energized infrared radiation sources (14, 16) disposed in a gas chamber (12) at different distances from an infrared detector (18). Both radiation sources are filtered at the absorbing wavelength of a gas to be monitored with one radiation source located proximate to the detector serving as a "virtual reference". The differential absorption between the two radiation sources is used to determine the concentration of a gas being monitored. In a modified sensor (30) one radiation source is seated in a parabolic recess (34a) in a base plate (34) with the radiation focused on one angled end wall (32d) of a dished shaped cover member (32) and reflected over to a second angled end wall (32e) and into the detector with the radiation sources and the detector attached directly to a circuit board (24) mounting the sensor.

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

Abstract: A sample cell for polarimetry is disclosed. It comprises: a base member having a tubular cavity for holding a specimen and for permitting a light to transmit therethrough, and a pair of light-transmitting windows for sealing a pair of open ends of the cavity; and a coil arranged around the base member for generating a magnetic field inside the cavity along an axial direction of the cavity. The specimen is supplied to the cavity through a channel for communicating the cavity with the outside.

Abstract: An apparatus and method for identifying one anesthetic agent contained in an anesthetic gas sample as the primary anesthetic agent and for identifying a second anesthetic agent as the secondary anesthetic agent is based on the use of minimum alveolar concentration (MAC). The primary agent is identified as the anesthetic agent which has the highest percent of its MAC at its measured volume concentration. The secondary agent is identified as the anesthetic agent which has the second highest percentage of its MAC at its measured volume concentration. Certain minimum threshold levels must be met before an anesthetic agent is identified either as the primary or secondary agent.