Abstract: A system and method for optical interrogation and measurement of a hydrocarbon fuel gas includes a light source generating light at near-visible wavelengths. A cell containing the gas is optically coupled to the light source which is in turn partially transmitted by the sample. A spectrometer disperses the transmitted light and captures an image thereof. The image is captured by a low-cost silicon-based two-dimensional CCD array. The captured spectral image is processed by electronics for determining energy or BTU content and composition of the gas. The innovative optical approach provides a relatively inexpensive, durable, maintenance-free sensor and method which is reliable in the field and relatively simple to calibrate. In view of the above, accurate monitoring is possible at a plurality of locations along the distribution chain leading to more efficient distribution.

Abstract: A multi-pass optical cell for measuring the concentration of one or more species in a fluid to be monitored includes a sample region; a source of collimated radiation; a detector device for sensing the intensity of the radiation; at least two reflective surfaces for reflecting in a first direction in the sample region a number of times the radiation from the source and delivering it to the detector device.

Abstract: An off-line-locked laser diode species monitor system includes: reference means for including at least one known species having a first absorption wavelength; a laser source for irradiating the reference means and at least one sample species having a second absorption wavelength differing from the first absorption wavelength by a predetermined amount; means for locking the wavelength of the laser source to the first wavelength of the at least one known species in the reference means; a controller for defeating the means for locking and for displacing the laser source wavelength from said first absorption wavelength by said predetermined amount to the second absorption wavelength; and a sample detector device for determining laser radiation absorption at the second wavelength transmitted through the sample to detect the presence of the at least one sample species.

Abstract: A selective chemical species detector including a conductive polymer based sensing element having a detectable characteristic, for example, the polymer resistivity, permanently altered on exposure to a first chemical species and not permanently altered on exposure to a second chemical species. The detector then determines a permanent change in the detected characteristic and indicates the presence of a chemical species on detection of a such a permanent characteristic change. Also disclosed is a method of fabricating such a sensing element to achieve the desired selectivity.

Abstract: A selective chemical species detector including a conductive polymer based sensing element having a detectable characteristic, for example, the polymer resistivity, permanently altered on exposure to a first chemical species and not permanently altered on exposure to a second chemical species. The detector then determines a permanent change in the detected characteristic and indicates the presence of a chemical species on detection of a such a permanent characteristic change. Also disclosed is a method of fabricating such a sensing element to achieve the desired selectivity.

Abstract: An ambient surface contamination sensor including a source for supplying gas, which is energized before it reaches the surface being sensed so that it is capable of transferring energy to the contaminants on the surface or vapor originating therefrom. The sensor then detects the optical emission from the gas passed over the surface within a selected wavelength band characteristic of the presence on the surface of the contaminant, and indicates the presence of the contaminant on the surface when such an emission is detected.

Abstract: A wavelength-locked laser gaseous species monitor including a variable wavelength laser with a laser output actively stabilized to a wavelength at or near an absorption wavelength of the species being monitored. The laser is modulated about that wavelength to establish a modulated output with a known frequency and bandwidth. The modulated output is passed through the sample being monitored and then collected. An even harmonic of the collected output with respect to the modulation frequency is determined, and the presence in the sample of the species being monitored is detected from the even harmonic signal.

Abstract: A gas species monitor system includes a sample volume for receiving a gas to be monitored; an external, independent laser source; means for directing the laser radiation to the volume; a multipass optical cell, responsive to the means for directing, for multiplying the laser radiation intensity in the sample volume; means for continuously flowing the gas to be monitored through the sample volume; a narrow bandpass filter; means for collecting more than a steradian of Raman scattered radiation from the sample in the volume and directing the collected radiation in parallel through the narrow bandpass filter; and means responsive to the parallel radiation from the filter for detecting the Raman scattered radiation representative of the concentration of the species in the gas sample being monitored.

Abstract: A leak detector for monitoring, in an area being investigated, the presence of a liquid having a characteristic fluorescence spectrum. The leak detector includes a radiation source, with the radiation provided to the area being investigated. The detector also includes a collector for collecting radiation, in the fluorescence emission band of the liquid being monitored, emitted from the area being investigated. The presence of this liquid is sensed by detection of a threshold level of collected radiation. The size of a stain of the liquid relative to the size of the field of view of the collector is then determined.

Abstract: An infrared trace element detection system including an optical cell into which the sample fluid to be examined is introduced and removed. Also introduced into the optical cell is a sample beam of infrared radiation in a first wavelength band which is significantly absorbed by the trace element and a second wavelength band which is not significantly absorbed by the trace element for passage through the optical cell through the sample fluid. The output intensities of the sample beam of radiation are selectively detected in the first and second wavelength bands. The intensities of a reference beam of the radiation are similarly detected in the first and second wavelength bands. The sensed output intensity of the sample beam in one of the first and second wavelength bands is normalized with respect to the other and similarly, the intensity of the reference beam of radiation in one of the first and second wavelength bands is normalized with respect to the other.

Abstract: An infrared monitor for measuring the presence of at least one gas phase molecular species including a sample path for containing a sample to be monitored for the molecular species. A sample beam of infrared source emission of the molecular species to be monitored for passage through the sample path is provided to the sample path. The sample beam includes at least one primary spectral emission line which is significantly absorbed by the molecular species. The decrease in the intensity of the at least one primary infrared source spectral emission line passing through the sample path is detected as a function of the absorption of the at least one line by the molecular species present in the sample.

Abstract: An infrared species specific emission source which includes a closed container having at least one transparent portion for containing at least one specific molecular species. The molecular species within the container is heated sufficiently to cause the species to emit a characteristic infrared spectal emission through the at least one transparent portion of the container to the infrared instrument.

Abstract: A spark discharge trace element detection system is provided which includes a spark chamber including a pair of electrodes for receiving a sample of gas to be analyzed at no greater than atmospheric pressure. A voltage is provided across the electrodes for generating a spark in the sample. The intensity of the emitted radiation in at least one primary selected narrow band of the radiation is detected. Each primary band corresponds to an element to be detected in the gas. The intensity of the emission in each detected primary band is integrated during the afterglow time interval of the spark emission and a signal representative of the integrated intensity of the emission in each selected primary bond is utilized to determine the concentration of the corresponding element in the gas.

Abstract: A spark spectroscopic high-pressure gas analyzer including a spark chamber, having a pair of electrodes, for receiving a sample of the pressurized gas to be analyzed. A voltage is provided across the electrodes for generating a spark in the pressurized gas sample. A selected wavelength band of radiation emitted from the spark discharge in the pressurized gas corresponding to a component to be sensed in the gas is detected. The intensity of the emission in the wavelength band is integrated during the afterglow time interval of the spark emission and a signal representative of the integrated intensity of the emission in the selected narrow wavelength band is employed to determine the proportion of the component in the gas.

Abstract: An ultraviolet absorption hygrometer is provided including a source of pulsed ultraviolet radiation for providing radiation in a first wavelength region where water absorbs significantly and in a second proximate wavelength region where water absorbs weakly. Ultraviolet radiation in the first and second regions which has been transmitted through a sample path of atmosphere is detected. The intensity of the radiation transmitted in each of the first and second regions is compared and from this comparison the amount of water in the sample path is determined.