Portable remote laser sensor for methane leak detection
First Claim
1. A portable, low wattage system for remotely detecting methane gas concentrations in the atmosphere from radiation reflected from a topographical target, said radiation including thermal and solar-type background noise, including methane-related laser wavelengths to be analyzed, said system comprising:
- means for generating a first laser beam at a first wavelength coincident with a natural absorption line of methane gas;
means for generating a second laser beam at a second wavelength which is not a strong absorption line of methane gas;
means for successively interrupting said first and second laser beams;
means for directing said first and second laser beams at a topographical target;
collecting means for focusing a portion of said reflected laser radiation;
narrowband optical filter means centered near said first and second wavelengths for passing said focused radiation, including the wavelengths to be analyzed and for effectively reducing said thermal and solar-type background noise;
optical detector means for detecting the intensity of incident laser radiation and generating a detector signal representative of such intensity;
signal processing means synchronized to the operation of said means for interrupting said laser beams for performing processing of the data from said optical detector to effectively cancel out the background noise while providing an output signal indicative of the relative intensity of said radiation at said first wavelength.
2 Assignments
0 Petitions
Accused Products
Abstract
A portable laser system for remote detection of methane gas leaks and concentrations is disclosed. The system transmitter includes first and second lasers, tuned respectively to a wavelength coincident with a strong absorption line of methane and a reference wavelength which is weakly absorbed by methane gas. The lasers are aimed at a topographical target along a system axis and the beams successively interrupted by a chopper wheel.
The system receiver includes a spherical mirror for collecting the reflected laser radiation and focusing the collected radiation through a narrowband optical filter onto an optial detector. The filter is tuned to the wavelength of the two lasers, and rejects background noise to substantially improve the signal-to-noise ratio of the detector. The output of the optical detector is processed by a lock-in detector synchronized to the chopper, and which measures the difference between the first wavelength signal and the reference wavelength signal.
-
Citations
21 Claims
-
1. A portable, low wattage system for remotely detecting methane gas concentrations in the atmosphere from radiation reflected from a topographical target, said radiation including thermal and solar-type background noise, including methane-related laser wavelengths to be analyzed, said system comprising:
-
means for generating a first laser beam at a first wavelength coincident with a natural absorption line of methane gas; means for generating a second laser beam at a second wavelength which is not a strong absorption line of methane gas; means for successively interrupting said first and second laser beams; means for directing said first and second laser beams at a topographical target; collecting means for focusing a portion of said reflected laser radiation; narrowband optical filter means centered near said first and second wavelengths for passing said focused radiation, including the wavelengths to be analyzed and for effectively reducing said thermal and solar-type background noise; optical detector means for detecting the intensity of incident laser radiation and generating a detector signal representative of such intensity; signal processing means synchronized to the operation of said means for interrupting said laser beams for performing processing of the data from said optical detector to effectively cancel out the background noise while providing an output signal indicative of the relative intensity of said radiation at said first wavelength. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17)
-
-
18. A portable, low wattage system for detecting methane gas concentrations in the atmosphere from reflected laser radiation which includes methane wavelengths to be analyzed and thermal, solar or room light background noise, said system comprising:
-
laser means adapted for selectively generating a laser beam at either a first wavelength coincident with a natural absorption line of methane gas or at a second wavelength which is not a strong absorption line of methane gas; control means coupled to said laser means for alternatively selecting said laser beam at said first wavelength and then said seond wavelength; means for directing said laser means at a topographical target; collecting means for focusing a portion of the laser radiation and background noise reflected from said target; narrowband optical filter means centered near said first wavelength for passing said focused first and second wavelengths of laser radiation and effectively reducing said background noise by a factor of up to four; optical filter means responsive to the signals passed through said narrowband optical filter means for detecting the intensity of incident laser radiation and generating a detector signal representative of such intensity; and signal processing means synchronized to the operation of said selecting means for processing the data from said optical detector and providing an output signal indicative of the relative intensity of said laser radiation at said first wavelength. - View Dependent Claims (19, 20, 21)
-
Specification