High-Accuracy Mid-IR Laser-Based Gas Sensor
First Claim
1. A gas sensor system for detecting and measuring the concentration of a gaseous molecular species within an environment having an ambient temperature and an ambient pressure, the system comprising:
- a gas cell operable so as to receive the sample gas from the environment;
a vacuum system fluidically coupled to the gas cell operable to maintain the sample gas within the gas cell at a predetermined pressure less than the ambient pressure;
a pressure sensor operable to sense a pressure of the sample gas within the gas cell;
a thermally insulated enclosure having the gas cell disposed therein;
a heat source or heat exchanger operable to influence a temperature of the interior of the thermally insulated enclosure;
a light source within the thermally insulated enclosure operable to provide a mid-infrared (mid-IR) light into the gas cell so as to be transmitted through the sample gas therein, wherein a wavelength of the mid-IR light coincides with a rotationally resolved absorption line of the gaseous molecular species;
a photodetector within the thermally insulated enclosure operable to receive the mid-IR light transmitted through the sample gas in the gas cell; and
a control system electronically coupled to the vacuum system and to the pressure sensor operable to maintain the sample gas within the gas cell at the predetermined pressure to within one torr (1 Torr).
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Accused Products
Abstract
A gas sensor system is provided, comprising: a gas cell operable so as to receive a sample gas; a vacuum system fluidically coupled to the gas cell operable to maintain the sample gas within the gas cell at a sub-ambient pressure; a pressure sensor operable to sense a pressure of the sample gas; a thermally insulated enclosure having the gas cell therein; a heat source or heat exchanger operable to influence an interior temperature of the thermally insulated enclosure; a light source within the thermally insulated enclosure operable to provide a mid-infrared (mid-IR) light into and through the gas cell; a photodetector within the thermally insulated enclosure operable to receive the attenuated mid-IR; and a control system electronically coupled to the vacuum system and to the pressure sensor operable to maintain the sample gas within the gas cell at the predetermined pressure to within one torr (1 Torr).
96 Citations
33 Claims
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1. A gas sensor system for detecting and measuring the concentration of a gaseous molecular species within an environment having an ambient temperature and an ambient pressure, the system comprising:
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a gas cell operable so as to receive the sample gas from the environment; a vacuum system fluidically coupled to the gas cell operable to maintain the sample gas within the gas cell at a predetermined pressure less than the ambient pressure; a pressure sensor operable to sense a pressure of the sample gas within the gas cell; a thermally insulated enclosure having the gas cell disposed therein; a heat source or heat exchanger operable to influence a temperature of the interior of the thermally insulated enclosure; a light source within the thermally insulated enclosure operable to provide a mid-infrared (mid-IR) light into the gas cell so as to be transmitted through the sample gas therein, wherein a wavelength of the mid-IR light coincides with a rotationally resolved absorption line of the gaseous molecular species; a photodetector within the thermally insulated enclosure operable to receive the mid-IR light transmitted through the sample gas in the gas cell; and a control system electronically coupled to the vacuum system and to the pressure sensor operable to maintain the sample gas within the gas cell at the predetermined pressure to within one torr (1 Torr). - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22)
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23. A method for detecting and measuring the concentration of a gaseous molecular species within an environment having an ambient temperature and an ambient pressure comprising:
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(a) providing a light source capable of providing an emitted mid-IR light whose wavelength may be caused to traverse across the wavelength range of a rotationally resolved absorption line of the gaseous molecular species; (b) providing a gas cell; (c) providing a temperature-stabilized optical system for directing the mid-IR light from the light source into the gas cell so as to pass therethrough and, subsequently, from the gas cell to a photodetector; (d) providing a system for stabilizing the pressure of a sample gas flowing through the gas cell at a pressure less than the ambient pressure to within one torr (1 Torr); (e) providing a system for stabilizing the temperature of the sample gas flowing through the sample gas cell at a sample gas temperature greater than the ambient temperature to within one degree Kelvin (1°
K);(f) causing the sample gas from the environment to flow through the gas cell at the sample gas pressure and the sample gas temperature; (g) operating the light source so as to cause the wavelength of the emitted mid-IR light to repeatedly traverse across the wavelength range of the rotationally resolved absorption line; (h) operating the optical system so as to cause the emitted mid-IR light to pass through and be attenuated by the sample gas in the gas cell and so as to cause the attenuated mid-IR light to pass to the photodetector; (i) detecting the attenuated mid-IR light by the detector at each of a plurality of discrete data points, each data point corresponding to a respective wavelength during a wavelength traverse; (j) constructing a direct absorption spectrum of the rotationally resolved absorption line using the plurality of data points; and (k) determining the concentration of the gaseous molecular species from the direct absorption spectrum. - View Dependent Claims (24, 25, 26, 27, 28, 29, 30, 31, 32, 33)
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Specification