Portable remote laser sensor for methane leak detection

Patent · Tue Dec 18 04:00:00 EST 1984

OSTI ID:5796767

Grant, W B; Hinkley, Jr, E D

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.

• Assignee: The United States of America as represented by the Administrator of the National Aeronautics and Space Administration
• Patent Number(s): US 4489239
• OSTI ID: 5796767
• Country of Publication: United States
• Language: English

Related Subjects

03 NATURAL GAS
032000* -- Natural Gas-- Transport
Handling
& Storage
42 ENGINEERING
420300 -- Engineering-- Lasers-- (-1989)
ALKANES
BACKGROUND NOISE
DESIGN
DETECTION
ELECTROMAGNETIC RADIATION
ENERGY SYSTEMS
EQUIPMENT
FILTERS
HYDROCARBONS
LASER MIRRORS
LASER RADIATION
LASERS
LEAKS
MEASURING INSTRUMENTS
METHANE
MIRRORS
MONITORING
MONITORS
NATURAL GAS DISTRIBUTION SYSTEMS
NOISE
OPTICAL FILTERS
ORGANIC COMPOUNDS
PIPELINES
PORTABLE EQUIPMENT
RADIATIONS
REMOTE SENSING
SIGNAL-TO-NOISE RATIO
WAVELENGTHS