Abstract: A non-dispersion type infrared analyzer for simultaneously determining plural components of a sample fluid, wherein a standard fluid and a sample fluid are alternately supplied in a cell and a plurality of pneumatic detectors, each of which corresponds respectively to one component to be determined, are arranged optically in series with respect to a light source. The extremely troublesome zero-adjustment, adjustment of the phases and re-adjustment of the compensation for eliminating the influences of interference components due to changes in the zero-drift or the deviation of phases are not required.

Abstract: A two-beam, infrared gas analyzer includes a front and a rear detection cell in each path filled with gas of the type to be detected; and a pressure-differential chamber with capacitor pick-up is connected to these front and rear cells. The rear cells are constructed to ensure substantially complete absorption of all radiation of the absorption band being characteristic of the component to be detected. In one example, filters are interposed between front and rear cells for broadband, i.e., nonselective attenuation. Alternatively, the rear cells are connected to a reservoir of the same gas to attenuate pressure variations. Either case enhances frequency selectivity by reducing cross sensitivity.

Abstract: The highly sensitive spectrophone assembly of the subject invention simultaneously and continuously provides an accurate measure of the absorption of electromagnetic radiation by atmospheric gases and particulate matter by providing successive flow through chambers. The gases and particulate matter pass through the first chamber, are directed through a filter where the particulate matter is removed, leaving the gases to flow through the second chamber. The signal representative of the absorption of energy is generated in each chamber and fed into a differential amplifier, to provide an accurate indication of the particulate matter in the atmosphere being monitored. Grounding one side yields a signal attributable to the gaseous absorption.

Abstract: The sensitivity and selectivity of a two beam analyzer operating with negative filtering and differential absorption-pressure detection is improved by employing differently long cells for the sample gas in the two beam paths, which reduces the effect resulting from overlapping absorption bands of the wanted and of unwanted components in the sample gas.

Abstract: The photometer comprises a light source, a reference cuvette containing a reference gas, a measurement cuvette containing a gas component whose concentration is to be measured accompanied by a carrier gas, a light modulator for effecting antiphase modulation of the infrared light passing through the two cuvettes, and a detector arrangement comprised of two gas-filled absorption chambers arranged one behind the other as well as a transducer for converting pressure changes induced in the absorption chambers into a measurement signal. The carrier gas consists of a plurality of component gases whose relative proportions fluctuate. The gas in the absorption chambers includes a gas component identical to the gas whose concentration is to be measured in the measurement cuvette, accompanied by an inert gas.

Abstract: An infrared gas analyzer includes side-by-side measuring and comparison vessles S, V containing sample and reference gases alternately exposed to infrared light through a rotary chopper CH. The end windows of the vessels are transparent, and a detector D containing two series chambers D1, D2 filled with a gas of the same kind as the component gas to be analyzed is axially disposed below the vessels. A capacitive diaphragm sensor is coupled between the chambers to detect pressure variation differences therebetween, and an adjustable reflecting means is disposed below the transparent bottom window of the second chamber to reflect back a portion of the light energy passing therethrough. The degree of reflection is suitably adjusted so that any interference gas component has an equal influence on the absorption curves of both chambers, whereby its effects are self-cancelling.

Abstract: A differential optoacoustic absorption detector employs two tapered cells in tandem or in parallel. When operating in tandem, two mirrors are used at one end remote from the source of the beam of light directed into one cell back through the other, and a lens to focus the light beam into the one cell at a principal focus half way between the reflecting mirror. Each cell is tapered to conform to the shape of the beam so that the volume of one is the same as for the other, and the volume of each receives maximum illumination. The axes of the cells are placed as close to each other as possible in order to connect a differential pressure detector to the cells with connecting passages of minimum length. An alternative arrangement employs a beam splitter and two lenses to operate the cells in parallel.

Abstract: An infrared laser absorption spectrometer is disclosed wherein a pair of detector cells are disposed in series relative to the laser beam path, such beam path preferably being within the optical cavity of the laser. The laser beam is modulated to produce a modulation of the absorption, if any, by the sample materials in the two cells. Modulated absorption by the sample or samples produces an acoustic wave in each cell which is detected by a suitable microphone and subtracted so as to produce a difference signal corresponding to the difference in absorption between the two cells so that undesired background effects are cancelled, such as window heating, absorption by a carrier gas or the like which is common to both cells. A mirror placed over one end of one of the cells allows a two cell optoacoustic detector geometry having only two windows therein.

Abstract: A relationship exists between the concentration of ethanol in human breath and blood. Ethanol absorbs infra-red 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.

Abstract: In an infrared laser absorption spectrometer, an infrared laser beam of predetermined wavelength, in the infrared absorption spectrum, is beamed into a liquid sample under analysis. Components of the liquid sample absorb energy from the infrared beam, as a function of the infrared wavelength of the beam, to produce heating of the liquid. A thermal detector is disposed in heat exchanging relation with the liquid sample for detecting the heating effect in the liquid due to absorption of the infrared radiation. This detection scheme is particularly useful for monitoring the effluent of a liquid chromatograph as it provides specific detection.

Abstract: Sample material of retention time peaks of a chromatograph are exposed to infrared radiation at first and second wavelengths and the absorption of the infrared energy by the sample peak is measured. The measured infrared absorption at the first and second wavelengths is correlated with the retention time of the sample peak as an identification of the sample material. In addition, overlapping retention time peaks are resolved by detecting the change in the ratio of the infrared absorption at the first and second wavelengths as a function of retention time for a given peak.

Abstract: An infrared laser absorption spectrometer is disclosed wherein a pair of detector cells are disposed serially along the laser beam path. The laser beam is modulated to produce a modulation of the absorption by the sample materials in the two cells. Modulated absorption by the samples produces an acoustic wave in each cell which is detected by a suitable microphone and subtracted so as to produce a difference signal corresponding to the difference in infrared absorption between the two cells so that undesired background effects common to both cells are cancelled. A pressure controller, which is responsive to the pressure difference between the sample pressure in the two cells at a frequency substantially below the beam modulation frequency is employed for controlling the pressure differential. In one embodiment the pressure controller includes a compliant membrane partitioning the two cells so that the membrane may move so as to equalize the pressures.

Abstract: Dual-beam comparison of gas absorption characteristics in which a single source and single detector of radiant energy and single chopper disc are used in sample gas and reference gas paths. Ambient atmosphere or gas directed through a sample gas chamber can be analyzed. Multiple gas analyses, of a plurality of gases or a plurality of constituents of a gas, can be performed simultaneously utilizing the single chopper disc with a plurality of optical gas assemblies. Each such assembly includes a single source of radiant energy, means for directing the radiant energy along sample and reference gas paths to a single detector for such radiant energy. The multiple units are mounted so that the single chopper disc cyclically interrupts radiant energy in the respective sample and reference gas paths in predetermined phase relationship. The combined sample gas and reference gas path response of the single detector for each gas analyzing unit is directed to phase-sensitive signal-separation circuit means.

Abstract: Disclosed herein is a method for detecting total reduced sulfur in a sample gas, comprising the steps of: introducing sample gas into a sample cell, passing detecting radiation of a wavelength between about 250 and about 330 nm. through the sample gas, detecting the intensity of the detecting radiation passing through the sample gas, introducing an oxygen-containing gas into the cell to form a gas mixture with a sample gas, heating the gas mixture to a temperature above about 200.degree.C., passing the detecting radiation through the heated gas mixture in the cell, and detecting the intensity of the detecting radiation passing through the gas mixture. The difference between the intensity of the detecting radiation passing through the gas mixture and that passing through the sample gas alone is indicative of the total reduced sulfur content of the sample gas. An apparatus to practice the above method is also disclosed.

Abstract: An auxiliary signal for the compensation of the difference signal created in optical-pneumatic receivers due to the absorption of radiation, such compensation being achieved by one or more electrical-pneumatic transmitters connected directly to the receiver chambers.

Abstract: A radiation receiver including three receiver layers for infrared gas analysis. The first and third layers are connected in parallel, and their pressure is compared with that of the second or middle layer to derive a pressure difference which compensates for certain measurement problems found in prior art devices.

Abstract: The contaminants in the exhaust gas emissions from a motor vehicle such as carbon monoxide (CO) and hydrocarbons (HC) are analyzed and the concentration of the contaminants together with other pertinent data is displayed in a digital manner. The exhaust gas emissions are fed into a sample cell contained within a nondispersive infrared analyzer and the absorption of an infrared radiation beam at selected wavelengths by the gas within the cell is measured. A reference cell containing a reference gas is also positioned in the infrared radiation beam path. By means of a rotating chopper disk positioned in the light path, the infrared radiation beam passes alternately through the reference cell and the sample cell and is focused at a plurality of detectors which are each sensitized to a narrow wave band by a filter and which receive the alternate sample cell and reference cell radiation pulses.

Abstract: A non-dispersive gas analyzing apparatus is described having a first chamber for containing a first gas, the density of which it is desired to determine. A source of radiant energy is provided for passing radiant energy through the first chamber. Modulation means are provided for modulating the radiant energy passing through the first chamber by modulating the volume of the chamber at the acoustic resonance frequency of the first gas and the chamber. Signal generating means including a second chamber for containing a gas which is heated by radiant energy emerging from the first chamber and a microphonic means responsive to the resulting pressurization in the second chamber is provided for generating a signal having a frequency and amplitude corresponding to the modulation of the radiant energy in the first chamber.