Backscatter absorption gas imaging system
First Claim
1. Method for detecting the presence of an invisible cloud of gas over a terrain, comprising:
- irradiating an area of the terrain within infrared laser radiation at a single wavelength which is absorbed by the gas and reflected or backscattered by the terrain;
detecting background infrared radiation from the irradiated area of the terrain;
detecting backscattered laser radiation from the irradiated area of the terrain;
producing an image of the terrain from the background radiation;
enhancing the image of the terrain with the backscattered laser radiation, the irradiating infrared radiation being of sufficient power so that the enhancement of the image by backscattered radiation is about equal in brightness to the image produced by the background radiation;
producing a region of detectable contrast or shadow over the image of the terrain when the gas is present, said region being primarily due to absorption of the laser light by the gas.
1 Assignment
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Accused Products
Abstract
A video imaging system for detecting hazardous gas leaks. Visual displays of invisible gas clouds are produced by radiation augmentation of the field of view of an imaging device by radiation corresponding to an absorption line of the gas to be detected. The field of view of an imager is irradiated by a laser. The imager receives both backscattered laser light and background radiation. When a detectable gas is present, the backscattered laser light is highly attenuated, producing a region of contrast or shadow on the image. A flying spot imaging system is utilized to synchronously irradiate and scan the area to lower laser power requirements. The imager signal is processed to produce a video display.
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Citations
17 Claims
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1. Method for detecting the presence of an invisible cloud of gas over a terrain, comprising:
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irradiating an area of the terrain within infrared laser radiation at a single wavelength which is absorbed by the gas and reflected or backscattered by the terrain; detecting background infrared radiation from the irradiated area of the terrain; detecting backscattered laser radiation from the irradiated area of the terrain; producing an image of the terrain from the background radiation; enhancing the image of the terrain with the backscattered laser radiation, the irradiating infrared radiation being of sufficient power so that the enhancement of the image by backscattered radiation is about equal in brightness to the image produced by the background radiation; producing a region of detectable contrast or shadow over the image of the terrain when the gas is present, said region being primarily due to absorption of the laser light by the gas. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. Apparatus for detecting the presence of an invisible cloud of gas over a terrain comprising:
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an imaging device, the device having a field of view which can be directed at an area of the terrain to detect the presence of the gas therein; a single infrared laser operating at a wavelength which is absorbed by the gas to be detected and reflected or backscattered from the terrain, the laser being positioned to irradiate the field of view of the imaging device, the imaging device being responsive to backscattered laser radiation and to background infrared radiation from the terrain in the field of view, the imaging device producing an image of the terrain in the field of view from the backscattered and background radiation if no gas is present, the infrared laser having sufficient power so that the contribution to the image of the terrain from the backscattered radiation is approximately equal to the contribution from the background radiation, the imaging device producing a region of contrast or shadow on the image of the terrain when the gas is present, said region being primarily due to the attenuation of the backscattered laser radiation by the gas; and video display means operatively connected to the imaging device to display an image of the field of view and show the presence of the gas cloud. - View Dependent Claims (10, 11, 12, 13, 14, 15, 16, 17)
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Specification