Patent ID: 9007594
Filing Date: 2015-04-14
Classification: G01N

Abstract:
1. A fiber laser gas detection system using active feedback compensation by a reference cavity, said system comprising: an optical fiber laser consists of a laser diode pump source, a wavelength division multiplexer, an active optical fiber and a fiber Bragg grating connected successively; an optical isolator coupled with said wavelength division multiplexer for blocking a reverse light transmission in said active fiber; a coupler connected with said optical isolator for dividing the laser light after being isolated by the optical isolator into a reference beam, a detecting beam and an intensity measuring beam according a certain ratio of power; a reference gas chamber, which is introduced with a reference gas of the same composition as that of the gas to be detected and of a known concentration, and receives the reference beam allocated from the coupler and makes the beam pass through the reference gas; a detection gas chamber, which is introduced with the gas to be detected, and receives the detecting beam allocated from the coupler and makes the beam pass through the gas to be detected; a first photodetector connected to said reference gas chamber for receiving the reference beam passing through the reference gas chamber to generate a first light intensity signal; a second photodetector connected to said detection gas chamber for receiving the detecting light beam passing through the detection gas chamber to generate a second light intensity signal; a third photodetector connected to said coupler for receiving said intensity measuring beam to generate a third light intensity signal; a feedback control unit for receiving and comparing said first, second and third light intensity signals, and converting the comparison result into a feedback signal to adjust said pump source and said fiber Bragg grating.