Abstract: Contaminants are detected optically at concentrations below 100 part-per-million (ppm) and extending to a level approaching 1 part-per-trillion (ppt) by using intracavity laser spectroscopy (ILS) techniques. An optically-pumped solid-state laser (the ILS laser) is employed as a detector. The ILS laser comprises an ion-doped crystal medium contained in a linear laser cavity. A gas sample containing gaseous contaminant species is placed inside the laser cavity and on one side of the ion-doped crystal. The output signal from the ILS laser is detected and analyzed to identify the gaseous species (via its spectral signature). The concentration of the gaseous species can be determined from the spectral signature as well. One preferred embodiment of the present invention employs a linear cavity formed between two mirrors separated from the ion-doped crystal laser medium, wherein both ends of the ion-doped crystal are cut at Brewster's angle.

Abstract: The present invention provides a generally applicable apparatus and method for achieving measurements of a constituent in a sample. This is achieved by employing a detection means having a plurality of detectors responsive to radiation in a selected region of the spectrum, e.g., the infrared. In most embodiments, at least two of the detectors provide broad wavelength bandpass. If narrow bandpass sources or detectors are used, the information generated is processed in a manner similar to broadband information. The broad bandpass response of the detectors can be contrasted with the approach of classical spectrophotometry, in which the spectral response of the detectors is designed to be as narrow as feasible, and substantially narrower than the spectral features of the constituent or constituents of interest. The data is processed such that the contributions of known background constituents and scattering is eliminated prior to further processing, thereby yielding a better result in high background situations.

Abstract: Method and apparatus for freon and other refrigerant matching, particularly for servicing of air conditioning systems for automotive applications. The matching process is based upon the comparison of resistance or infrared absorption or other data readings of a gas-sensing resistance or infrared absorption or other transducer applied to the refrigerant fluid under test and corresponding data from reference refrigerants.

Abstract: A gas analyzer has a test chamber for a gas sample, an inlet for the gas sample and a gas sensor sensitive to gas movement, for determining the concentration of a constituent gas in the gas sample. The inlet is adapted to be connected to an inspiration line of a respirator. A shield is arranged so it covers the inlet of the test chamber, causing the gas sample to remain relatively still inside the test chamber during the analysis, regardless of the main flow of the gas to be analyzed. The gas analyzer can accordingly be devised for direct connection to the gas to be analyzed.

Abstract: Systems and methods for providing an ultra-stable measurement of the density of a fluid/gas species such as ozone in a mixture. The technique is based on information extracted from multi-wavelength light absorption, at which the species exhibits different absorption properties (coefficient values). The technique provides real-time compensation for short- and long-term instability in the light source and detector, and for detectable changes in the optical characteristics of the cell, thus improving the accuracy of the measurement while making frequent zeroing of the instrument unnecessary. In addition, the invention provides a high-performance technique for measuring ultra-high ozone densities using absorption at the Chappuis band.

Abstract: In an optoacoustic gas sensor having a sensor body (1, 2), a light source (10), a measurement cell (6) with a gas-permeable membrane (15), a measurement microphone (13), and an optical measurement filter (11) between the light source (10) and the measurement cell (6), a reference cell (7) is included that is separate from the measurement cell (6). The reference cell (7) has a reference microphone (14) that is shielded against optoacoustic signals from the gas to be detected via the reference cell being substantially free from intensity-modulated optical radiation having an absorption wavelength of the gas to be detected. The measurement signal, which indicates gas concentration, is obtained by subtraction of the signals from the two microphones (13, 14).

Abstract: In order to provide a measuring device for determining stoichiometric ratios when burning hydrocarbons by means of which stoichiometric ratios can be determined easily and reliably when burning hydrocarbons, it is proposed that a sensor be provided to detect an intensity of a first fluorescent radiation from C--H molecular fragments arising during the burning and a sensor be provided to detect an intensity of a second fluorescent radiation from molecular fragments arising during the burning and comprising only C atoms, that the sensors generate an intensity-dependent first and second sensor signal, respectively, on the basis of the first and the second fluorescent radiation, and that an evaluation circuit be provided which generates an output signal corresponding to a stoichiometric ratio from a ratio between the intensities of the first and the second fluorescent radiation.

Abstract: A gas spectrometer is provided having an enhanced capability for maintaining initial calibration conditions therewithin. The gas spectrometer is particularly apt for respiratory gas analysis applications and includes a housing assembly that defines an internal containment area(s), within which a radiation source, optical assembly, sample gas assembly and radiation detection assembly are positioned. A gas removal assembly is provided for removing one or more undesired gas component types from within the internal containment area during field use. The gas removal assembly is selectively retractable from the housing assembly to permit periodic servicing (e.g., replacement of CO.sub.2 absorbent) without requiring disassembly or recalibration of the spectrometer.

Abstract: A method and apparatus for detecting the presence of a specific concentration of gaseous species within a calibrated range in a gas sample is disclosed. The ILS gas detection system of the present invention simply comprises an ILS laser, a wavelength-selective optical element, and an optical detector. However, the potential or operational wavelength bandwidth of the ILS laser is preferably entirely included within one of the absorption bands or regions assigned to the intracavity gaseous species being monitored. Thus, within the calibrated range, the presence of the gaseous species changes the output laser wavelength or output intensity at a specific wavelength of the ILS laser. Consequently, only the wavelength of the output or the output intensity at the specific wavelength of the ILS laser need be monitored in order to quantitatively determine the concentration of the absorbing gaseous species within a calibrated range when using the ILS method of the present invention.

Abstract: A vehicle gas analyzing system for testing gas content in exhaust emitted from a vehicle is disclosed. The vehicle gas analyzing system is of a size and weight to be held in a user's hands. The system includes a housing having outer dimensions no greater than about 12".times.8".times.3", and has an inlet receiving exhaust emitted from the vehicle. A sensor assembly is disposed in the housing, receives the exhaust emitted from the vehicle through the inlet, and determines the content of a plurality of different gases in the exhaust. A user interface is disposed on an outside surface of the housing, allowing a user to input instructions to the system and to perceive output from the system.

Abstract: A method and apparatus for detecting the presence of a specific concentration of gaseous species within a calibrated range in a gas sample are disclosed. The ILS gas detection system of the present invention simply comprises an ILS laser and an optical detector. However, the potential or operational wavelength bandwidth of the ILS laser is preferably entirely included within one of the absorption bands or regions assigned to the intracavity gaseous species being monitored. Thus, within the calibrated range, the presence of the gaseous species changes the output laser intensity of the ILS laser. Consequently, only the intensity of the output of the ILS laser need be monitored in order to quantitatively determine the concentration of the absorbing gaseous species when using the ILS method of the present invention.

Abstract: A method and system for determining the presence of one or more components in a liquid substance including illumination of the substance utilizing a light with at least one definite wave length preferably within the almost infrared area and detecting transmitted and/or reflected light and analyzing the detected light wherein the detection is performed extremely fast so as to detect a step response corresponding to an approaching or fading light pulse transmitted or reflected through the substance.

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

Abstract: A gas monitor includes an infra-red source enclosed within a housing having inner surfaces which are reflective. Radiation emitted from the source reflects off ellipsoidal surfaces and intermediate planar surfaces to be focussed at a sensor, being reflected five times. Radiation is absorbed by gas within the housing and a comparison of the source intensity and detected intensity gives a measure of the gas concentration. Use of ellipsoidal reflective surfaces directs emitted radiation along a plurality of routes having substantially the same path length, hence giving an accurate measure of the gas concentration with a compact device. In another embodiment, off axis parabolas are used to direct the radiation through the gas.

Abstract: A fire detector with a maximum average response time of less than 1.5 minutes is obtained by combining a smoke detector with a CO.sub.2 detector that uses NDIR sensor technology. The smoke detector is used to detect smoldering fires and to help prevent false alarms attributable to the CO.sub.2 detector. The CO.sub.2 detector is used to rapidly detect fires by measuring the rate of change of CO.sub.2 concentration. A signal processor generates an alarm signal when a smoldering fire is detected or alarm logic indicates that a fire has been detected.

Abstract: A radiation source assembly is provided that is particularly apt for use in an anesthetic gas monitoring device (e.g., a gas spectrometer) to enhance maintenance of initial calibration conditions therewithin. In one embodiment a respiratory gas spectrometer includes a containment assembly that defines an internal containment area(s) within which a ceramic radiation source, an optical assembly, a sample gas assembly, and a radiation detection assembly are positioned. The radiation source assembly is provided for positioning and supporting the ceramic radiation source relative to the optical assembly within an internal containment area of the gas monitor. The radiation source assembly provides for enhanced sealing between the ceramic radiation source and adjoining componentry. The radiation source assembly is selectively retractable from the containment assembly to permit periodic servicing (e.g., replacement of the radiation source) without requiring disassembly of the gas spectrometer.

Abstract: A sample solution is stored in a total reflection cell, and a measuring beam is introduced from an incident optical system to be totally reflected, for measuring a total reflection absorption spectrum. Hydrogen peroxide contained in the sample solution is determined on the basis of absorbance at the position of any absorption peak of the spectrum which is present at 1200 to 1500 cm.sup.-1 or 2600 to 3000 cm.sup.-1. Hydrogen peroxide contained in an aqueous solution can be simply quantitatively analyzed through optical analysis.

Abstract: An infrared optical gas-measuring system with two infrared radiation sources (1, 2) and with at least one multispectral sensor (5). The system is suitable for determining the concentrations of different components of a gas flow. The two infrared radiation sources (1, 2) radiate in different spectral ranges with two different cycle frequencies f.sub.1, f.sub.2. The rays emitted are first passed through a radiation coupler (3), after which they pass through the gas flow to be measured, which is limited by windows (8), at right angles to the direction of flow. The rays finally enter a multispectral sensor (5), of which there is at least one, for measuring the intensity.

Abstract: Methods according to the invention include providing an OFA tool which subjects formation fluids to NIR illumination and which provides a spectral measurement of peaks at about 6,000 cm.sup.-1 and about 5,800 cm.sup.-1. The methods according to the invention also include calculating a ratio of the amplitudes of the absorption peaks to determine GOR. According to an alternate embodiment, the methods of calculating the ratio include referring to a database of spectra of hydrocarbons found in formation fluid and adjusting the amplitudes of the methane and oil peaks to account for the influences of other hydrocarbons on the spectrum of the formation fluid. A borehole apparatus for measuring the spectral peaks of oil and methane includes a testing region, a conduit for directing formation fluid into the testing region, a light source emitting at least near infrared rays into the testing region, a spectral detector optically coupled to the testing region, and a processor coupled to the spectral detector.

Abstract: An side stream infrared gas analyzer for detecting the concentration of a gaseous component of a substantially gaseous flow stream such as the expired air of a patient under anesthesia. The infrared gas analyzer comprises an infrared energy detector, a sample cell, and an infrared energy source which are designed to be small and to consume relatively little electrical power. The infrared energy detector converts the received incident radiation into at least one electrical signal representative of the received incident radiation and is preferably mounted directly onto a printed circuit board containing signal processing circuitry which processes the electrical detection signals provided by the infrared energy detector. The infrared energy detector also has a first infrared transmissive window on a detection side thereof through which the incident radiation passes for detection.

Abstract: An apparatus and method are disclosed for measuring the concentration of gases that are unstable or difficult contain in a sample cell. A frequency modulated laser is tuned to the frequency of a first spectral feature of a gas of interest and a laser beam is projected through a reference cell containing, at a selected pressure, a selected second gas that has a second spectral feature near the first spectral feature of the gas of interest. The laser is line-locked to an outer zero crossing of a third harmonic of the detected laser beam coincident with the first spectral feature. The concentration of the gas of interest is calculated from a second harmonic of a portion of the laser beam projected through a transmission medium containing the gas.

Abstract: A measuring cell (1) for the analysis of a gas sample by infrared absorption, with a measuring path (2) accommodating the gas sample, which has opposite limiting surfaces (7, 9) enclosing the gas sample, wherein a focusing optical component (8) is present at the first limiting surface (7) and an infrared radiation source and a radiation receiver (4) are arranged in the area of the second limiting surface (9) such that a measuring beam (13) emitted by the radiation source (3) is directed onto the radiation receiver (4) through the optical component, shall be improved such that it be suitable for the detection of gases with a long absorption path. A mirror surface (12) active for the measuring path (2) is present in the area of the second limiting surface (9), and the geometry of the optical component (8) is dimensioned such that there is an at least fourfold pass of the measuring beam (13) in the measuring path (2), utilizing the reflection of the beam on the mirror surface (12).

Abstract: The gas sample identification apparatus transmits at least one beam of light of predefined frequency band through a gas sample present in a gas sampling chamber. The presence and concentration of various agents in the gas sample are determined by a linear variable filter that selectively passes the light beam transmitted through the gas sample chamber to an array of detectors. The detectors are positioned to receive only a narrow passband component of the light beam. The output signals from the array of detectors is processed by a multivariate statistical processor to accurately identify both the presence and concentration of one or more agents contained in the gas sample.

Abstract: Contaminants are detected optically at concentrations below 100 part-per-million (ppm) and extending to a level approaching 1 part-per-trillion (ppt) by using intracavity laser spectroscopy (ILS) techniques. A diode laser-pumped solid-state laser (the ILS laser) is employed as a detector. The ILS laser comprises an ion-doped crystal medium contained in a laser cavity optically pumped by a diode laser pump laser. A gas sample containing gaseous contaminant species is placed inside the laser cavity and on one side of the ion-doped crystal. The output signal from the ILS laser is detected and analyzed to identify the gaseous species (via its spectral signature). The concentration of the gaseous species can be determined from the spectral signature as well.

Abstract: A solid object carrying a catalyzer thereon is placed in a closed reaction chamber into which test gases are supplied and is heated up to a temperature of 1000.degree. C. Adsorbates are formed on the surface of the solid object under the test gas flow in the closed reaction chamber. Infrared radiations radiated from the adsorbates are emitted through an infrared-transmissive window hermetically formed on a wall of the closed reaction chamber, and are analyzed by an infrared radiation spectrometer and observed by a microscope. The infrared-transmissive window is cooled down by a cooling device attached thereto so that the temperature of the window does not exceed a certain level, e.g., 200.degree. C. Thus, the adsorbates formed on the solid object can be detected and analyzed under conditions where the test gas is actually flowing and the temperature of the solid object is elevated up to a high level.

Abstract: The invention relates to a method and apparatus for determining the concentration of at least carbon dioxide in a gas mixture on the basis of the absorption of infrared radiation (2), said apparatus comprising: a radiation source (1), the radiation emitted thereby being aligned to travel through a measuring cell (4) containing a gas mixture (6) to be analyzed; an optical band-pass filter (10), which is transmissive to a first wavelength band and positioned on the path of radiation emerging from the measuring cell or entering into the measuring cell through which the radiation passes; and a first detector (14), positioned in the radiating direction downstream of said first band-pass filter and used for detecting the radiation intensity falling thereon. Said optical band-pass filter (10) has a band-pass which lies within the wavelength range of 4.38 .mu.m-4.47 .mu.m for measuring the total concentration of carbon dioxide by means of the absorption spectrum of a molecule .sup.13 CO.sub.

Abstract: A gas detector for detecting the presence of a light absorbing gas within an atmosphere (10) containing the gas includes a light source (12), a detector (14) arranged to detect a presence of incident radiation from the light source (12) and to provide an output signal (46) representative of the level of incident radiation from the light source (12). Electronic circuitry (130) is arranged to process the output signal (46) to provide an indication of the incident radiation. A power supply (40, 36) for cyclically energizing the light source (12) is also provided. The power supply is arranged to deliver substantially constant power at the or each level of energization of the light source (12).

Abstract: A cavity ring down spectroscopy (CRDS) system uses a free-running continuous wave (c.w.) diode laser stabilized by frequency-shifted optical feedback in the presence of strong reflections from a high-finesse Fabry-Perot resonator. The frequency-shifted feedback stabilization eliminates the need for tightly controlling the relative positions of the laser and resonator. Non-frequency-shifted feedback is used for linewidth broadening. An acousto-optic modulator placed between the diode laser output and the resonator input frequency-shifts light reflected by the resonator input, causing the laser to cycle in phase with a period equal to the inverse of the frequency-shift. The laser diode linewidth can be stabilized from several MHz for high resolution spectroscopy of species at low pressures, to several hundred MHz for lower resolution spectroscopy of species at atmospheric pressures.

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

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

Abstract: A system 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 gaseous sample contacting the suspected compound.

Abstract: A method and apparatus for an incipient fire detection system that receives gaseous samples and measures the light absorption spectrum of the mixture of gases evolving from heated combustibles includes a detector for receiving gaseous samples and subjecting the samples to spectroscopy and determining wavelengths of absorption of the gaseous samples. The wavelengths of absorption of the gaseous samples are compared to predetermined absorption wavelengths. A warning signal is generated whenever the wavelengths of absorption of the gaseous samples correspond to the predetermined absorption wavelengths. The method includes receiving gaseous samples, subjecting the samples to light spectroscopy, determining wavelengths of absorption of the gaseous samples, comparing the wavelengths of absorption of the gaseous samples to predetermined absorption wavelengths and generating a warning signal whenever the wavelengths of absorption of the gaseous samples correspond to the predetermined absorption wavelengths.

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: A Fourier-Transform Raman spectrometer was used to collect the Raman spectra of (208) commercial petroleum fuels. The individual motor and research octane numbers (MON and RON, respectively) were determined experimentally using the industry standard ASTM knock engine method. Partial Least Squares (PLS) regression analysis can be used to build regression models which correlate the Raman spectra (175) of the fuels with the experimentally determined values for MON, RON, and pump octane number (the average of MON and RON) of the fuels. Each of the models was validated using leave-one-out validation. The standard errors of validation (SEV) are 0.415, 0.535, and 0.410 octane numbers for MON, RON, and pump octane number, respectively. By comparing the standard error of validation to the standard deviation for the experimentally determined octane numbers, it is evident that the accuracy of the Raman determined values is limited by the accuracy of the training set used in creating the models.

Abstract: The method and apparatus for measuring a content of vaporous hydrogen peroxide in a gaseous medium within an enclosure includes a irradiating a portion of the gaseous medium with light, measuring an absorbance of light in a selected near-infrared wavelength range, and calculating the content of vaporous hydrogen peroxide from the measured absorbance of light.

Abstract: A portable instrument for locating leaks through the wall of a chamber uses a non-dispersive infrared (NDIR) type detector. The instrument includes a gas sampling probe into which a continuous sample of gas is drawn by a small suction pump. The sample is conducted from the probe through a flexible conduit and through a gas sample chamber. The gas sample chamber contains a source of light or infrared radiation and a detector. A narrow pass band filter is interposed between the source and the detector, and the pass band of the filter is centered on an absorption band of the test gas that is to be detected. When the test gas is present, it absorbs some of the radiation. The detector produces an electrical signal representative of the concentration of the test gas. The detector is connected to a signal processing circuit that responds to rapid changes of test gas concentration but ignores slow changes in concentration, thereby reducing the false alarm rate.

Abstract: An infrared gas analyzer for measuring low concentrations of a target gas, on the order of parts per million, in a sample gas is comprised of a gas sampling chamber, an infrared light source, and a power source for energizing the light source. A plurality of filters is provided to transmit infrared radiation at certain wavelengths. The wavelengths are chosen such that the effects of unwanted gases (such as water and carbon dioxide) can be removed from the final output signal. A plurality of infrared detectors are responsive to the filters for producing a plurality of electrical signals. A circuit is provided for combining the plurality of electrical signals to produce an output signal representative of the concentration of the target gas independently of other gases in the sample gas. A method of measuring low concentrations of a target gas is also disclosed.

Abstract: A cross-road motor vehicle exhaust gas analyzer uses tunable infrared laser differential absorption spectroscopy incorporating photon infrared detection to determine the absolute fractional absorption of a laser by the gaseous medium. Spectroscopic constants of the gaseous species of interest are applied to the absolute fractional absorption to calculate the pertinent absolute column densities. In addition to a laser that sweeps across one or more absorption line of an component of interest, the system of the invention includes a laser source tunable over an absorption line of a reference species; the calculated column density of the reference species is used to normalize the concentration of the component of interest to the fuel consumption rate of the motor vehicle.

Abstract: A gas analyzer for continuously determining the concentration of a gas in a gas mixture, having a measuring cell, a radiation source, a detector and signal processing facilities, characterized in that the radiation source is slidingly arranged in the measuring cell.

Abstract: An apparatus for measuring characteristics of a liquid including a channel through which, during operation, the liquid flows and a plurality of sensors for measuring characteristics of the liquid as it flows through the channel. The cross-sectional shape of the channel varies along its length, but the cross-sectional area of the channel is substantially constant so that, during operation, liquid flows through the channel at a substantially uniform speed. The sensors include an ultra-violet sensor and an infra-red sensor, each having a source and a detector of electromagnetic radiation arranged along an axis transverse to the channel. The axes of the two sensors are transverse to each other.

Abstract: A borehole tool analyzes the composition of gases flowing from a formation. The tool includes an optical fluid analyzer (OFA) and a gas analysis module (GAM). The OFA determines when fluid flowing into the tool has become substantially only gas. The gas is then diverted to the GAM, thereby avoiding the possibility of oil depositing itself on a optical window and interfering with a proper analysis. The GAM includes a near infrared ray light source, at least one photo-detector, a gas sample cell (or cells) having portions with different path lengths, each portion having an optical window, and fiber optics which direct light in first paths from the source to the sample cell, and from the sample cell to the photo-detectors. By providing cells with different path lengths, issues of dynamic range are obviated.

Abstract: A micromachined integrated opto-thermal sensor having a rapidly intensity varying or pulsing light source, an interference filter, shadow masking or reflective blocking of light from thermal sensors, or differential operation, a gas cavity into which the detected gas can flow into via a channel or filter, and a thermal detector elements to sense the heating of the gas caused by the absorption of light at a particular wavelength by the specific gas to be detected. Another version of the sensor is one with a dual cavity. One cavity contains the gas to be detected and the other cavity is sealed from the ambient environment and contains no gas. Signals from the detectors from the cavities are subtracted from each other resulting in the elimination of a fixed signal due to radiation impinging the detectors. A ratio of the signal from the detectors may be calculated for determining a presence of gas or fluid. The detector may have only a single cavity with two groups of thermal sensors.

Abstract: On line and essentially continuous measurements of hydrogen peroxide vapor in the presence of water vapor can be made using near infrared (NIR) spectroscopy using fiber optic cables to transmit infrared radiation between, e.g, a sterilization chamber and the NIR instrument. Hydrogen peroxide absorbs selectively at about 1420 nm, where water vapor also absorbs, but the absorbance at 1420 nm can be corrected for water vapor measurements at remote wavelengths where H.sub.2 O.sub.2 is transparent. The measurement process may be conveniently made by applying a multivariant statistical technique to the spectrum obtained over one or more bands within the 900-2000 nm region using the correlation obtained for a calibration set for which analogous measurements are made over the same region.

Abstract: On line and essentially continuous measurements of hydrogen peroxide vapor in the presence of water vapor can be made using near infrared (NIR) spectroscopy using fiber optic cables to transmit infrared radiation between, e.g, a sterilization chamber and the NIR instrument. Measurement of hydrogen peroxide concentration in the foregoing manner is incorporated into a control system which automatically adds gaseous hydrogen peroxide to the sterilization chamber when the measured concentration falls below a precalculated value. Such a control system ensures the presence in the sterilization chamber of an adequate concentration of gaseous hydrogen peroxide to effect sterilization throughout the sterilization procedure.

Abstract: A sensor with multiple radiation detectors with two or more of the detectors sensitive to a common narrow band of radiation and others of the detector not sensitive to this narrow band of radiation. The detectors may be bolometers with bandpass filters over the bolometers.

Abstract: A miniaturized NDIR gas sensor is manufactured using semiconductor micromachining techniques from a semiconductor material such as Si or GaAs. The NDIR gas sensor comprises an optical waveguide, a light source at one end of the waveguide, at least one light detector at the end of the waveguide opposite the light source, a diffusion type gas sample chamber formed within the waveguide and interposed in the optical path between the light source and light detector so that the light source and light detector are thermally isolated from the gas sample, and a separate bandpass filter interposed between the light source and each light detector. A miniaturized NDIR gas sensor is also provided in which the light source and light detector are located on the same end of the optical waveguide is also provided. Because the NDIR sensor is fabricated out of a semiconductor material, the source driver and signal processing electronics may be added directly to the sensor using integrated circuit fabrication techniques.

Abstract: The present invention is a method to determine the chemical concentration of one or more of a number of the constituent classes of a feed to a catalytic cracking process. These constituent classes which are referred to as "lumps", include 14 different molecular types in 4 different boiling range fractions. A specific lump will include all individual molecular components which are expected to react in a similar way in the catalytic cracking unit.

Abstract: The present invention provides a generally applicable apparatus and method for achieving measurements of a constituent in a sample. This is achieved by employing a detection means having a plurality of detectors responsive to radiation in a selected region of the spectrum, e.g., the infrared. In most embodiments, at least two of the detectors provide broad wavelength bandpass. If narrow bandpass sources or detectors are used, the information generated is processed in a manner similar to broadband information. The broad bandpass response of the detectors can be contrasted with the approach of classical spectrophotometry, in which the spectral response of the detectors is designed to be as narrow as feasible, and substantially narrower than the spectral features of the constituent or constituents of interest. The data is processed such that the contributions of known background constituents and scattering is eliminated prior to further processing, thereby yielding a better result in high background situations.

Abstract: A spectrophotometer for providing an image of a radiation scattering medium having one or more radiation attenuating constituents is disclosed herein. The spectrophotometer includes a light source for illuminating the scattering medium with electromagnetic radiation of at least one wavelength. In one embodiment a time-gated detector serves to detect, during a predefined detection interval, the electromagnetic radiation having traversed a distribution of path lengths during propagation through a region of the medium. A photon counting apparatus or the like measures the intensity of the detected portion of the electromagnetic radiation, wherein the measured intensity is a function of attenuation of the region within the medium. A display apparatus is operative to generate the image in accordance with the measured intensity.

Abstract: A spectral analyzer has a high efficiency optical collector having a first concave reflector portion and an opposed second concave reflector portion providing an exit passage therethrough, and a light emitting source of a predetermined wavelength range is positioned in the collector so that the light is collected and directed to the exit passage. A specimen holder is positioned adjacent the exit passage and has windows at its entrance and exit ends. An elongated reverse non-imaging optical member which has a peripheral wall reflecting light rays entering through the exit window of the holder reduces the angle of the rays relative to the optical axis of the optical member as they pass therethrough. The light passing through the exit end of the optical member enters a detector assembly including at least one photo detector sensitive to a predetermined wavelength of light, and at least one optical filter disposed between the optical member and the photodetector to pass light of the predetermined wavelength.