Method and apparatus for remotely detecting gases in the atmosphere
First Claim
1. A method of detecting the presence in the atmosphere of a gas which absorbs or emits infrared radiation within a defined wavelength region and determining its location with respect to at least one fixed background reference point, wherein(a) a number of points within a circumscribed background area, which are at a temperature different from the average temperature of the intervening atmosphere are viewed by the imaging optics of an imaging-analyzing means having a first sensor means and a second sensor means capable of generating electrical output signals that are responsive to the resulting net radiative flux transmitted through the atmosphere;
- the first sensor means having a higher sensitivity and the second sensor means having a lower sensitivity to the gas of interest in the defined infrared wavelength region;
(b) the amplitudes of the output signals generated by said sensor means are ratioed pixel-by-pixel within the defined infrared wavelength region; and
(c) an image signal responsive to the ratio of said output signal amplitudes is produced, said image signal being displayed on a display means, the image indicating the presence of the gas of interest at at least one point within the circumscribed area being surveyed.
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Abstract
Presence and location of infrared radiation-absorbing or emitting gases in the atmosphere can be ascertained by means of an infrared imaging-analyzing means which views a given scene and receives infrared radiation therefrom. Analytic and reference beams are produced, the latter having reduced sensitivity to the gas of interest, and are converted to electric signals, which are processed in real time to provide a signal corresponding to their ratio. This ratio signal is further processed to generate an image, which can be displayed and viewed. This technique is particularly suitable for surveying large areas for seepage of methane or other hydrocarbon gases from underground gas and/or oil deposits.
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Citations
24 Claims
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1. A method of detecting the presence in the atmosphere of a gas which absorbs or emits infrared radiation within a defined wavelength region and determining its location with respect to at least one fixed background reference point, wherein
(a) a number of points within a circumscribed background area, which are at a temperature different from the average temperature of the intervening atmosphere are viewed by the imaging optics of an imaging-analyzing means having a first sensor means and a second sensor means capable of generating electrical output signals that are responsive to the resulting net radiative flux transmitted through the atmosphere; -
the first sensor means having a higher sensitivity and the second sensor means having a lower sensitivity to the gas of interest in the defined infrared wavelength region; (b) the amplitudes of the output signals generated by said sensor means are ratioed pixel-by-pixel within the defined infrared wavelength region; and (c) an image signal responsive to the ratio of said output signal amplitudes is produced, said image signal being displayed on a display means, the image indicating the presence of the gas of interest at at least one point within the circumscribed area being surveyed. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14)
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15. An apparatus for detecting the presence and determining the location of an infrared radiation-absorbing or emitting gas in the atmosphere, said apparatus comprising:
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(1) an infrared imaging-analyzing means capable of viewing a circumscribed background area, receiving infrared radiation therefrom, producing in real time an analytic beam and a reference beam, and sensing said beams with two separate sensor means, one sensor means having greater sensitivity to the gas of interest than the other; (2) signal processing means for ratioing pixel-by-pixel the amplitudes of said reference and analytic signals; and (3) means for producing an image corresponding to the results of said ratioing. - View Dependent Claims (16, 17, 18, 19, 20, 21, 22, 23, 24)
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Specification