Gas detection method and device based on local light signal demodulation and modulation technology

Abstract

The invention relates to a synchronous light signal demodulation technology and particularly relates to a gas detection method and device based on a local light signal demodulation and modulation technology. The gas detection method comprises the following steps: (a) dividing laser, which is subjected to wavelength modulation and is output by a semiconductor laser device, into two beams; (b) inputting one beam of light as detection light into a sensing head for gas detection and inputting a signal carrying information of gas to be detected into a lock-in amplifier; (c) converting the other beam of light into a corresponding electric signal, filtering to remove noises, amplifying, locking, and transmitting the electric signal to a synchronous end of the lock-in amplifier; and (d) analyzing the signal, which is synchronously demodulated by the lock-in amplifier, to obtain concentration information of the gas to be detected. According to the gas detection method and device, a synchronous signal is extracted at a detection system end and the advantage of long-distance transmission of light signals in an optical fiber is utilized so as to avoid the disadvantages of great loss, high cost and the like generated when electric signals are transmitted in a long distance.

Description

technical field [0001] The invention relates to a technology for synchronous demodulation of optical signals, in particular to a gas detection method and device based on the technology of local demodulation and modulation of optical signals. Background technique [0002] Based on the principle of optics, the gas detection technology using laser as the light source has received extensive attention and research in trace gas detection due to its advantages of high reliability, high sensitivity, good selectivity, continuous online work and no need for manual supervision. When detecting trace gases in harsh environments such as power plants, mines, and virgin forests, if the existing method is used, the laser is usually placed not far from the measurement site. It is well known that the cost of the laser is relatively high. Generally speaking, the cost of lasers accounts for more than one-third of the entire system, or even more than 50%. It is very unsafe to place in the wild...

AI Technical Summary

Problems solved by technology

[0005] The present invention provides a gas detection method and device based on local demodulation and modulation optical signal technology to solve the problem of low utilization efficiency, high cost, small detection coverage, inability to adapt to the field environment, and safety factor of the current gas sensor based on laser. low level problem

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