TDLAS (Tunable Diode Laser Absorption Spectroscopy) gas monitoring device having time division multiplexing function

Abstract

The invention discloses a TDLAS (Tunable Diode Laser Absorption Spectroscopy) gas monitoring device having a time division multiplexing function. The device comprises a DFB (Distributed Feed Back) laser used for outputting a light signal to an electro-optical modulator; the electro-optical modulator is connected with an air chamber unit through an optical circulator; a pulsed light signal fed back from the air chamber unit is input to a photoelectric detector through the optical circulator; the photoelectric detector is connected with a pulse detector and a lock-in amplifier respectively; both output of the pulse detector and the lock-in amplifier is connected with a digital signal processor; the lock-in amplifier is connected with a signal generator. By adopting a time division multiplexing technology, the position of a gas sensor and the gas absorption condition at the position are totally associated so that interferences to sensor signals caused by loss of optical fiber links which are not at the position of the sensor are avoided. All monitoring points can run in a manner of being connected end to end in series by using single-core optical fibers, so that the capacity of the monitoring points supported by the single-core optical fibers is greatly increased and position identification is more direct and reliable.

Description

technical field [0001] The invention relates to the field of optics, in particular to a TDLAS gas monitoring device capable of time-division multiplexing, which is applicable to various metallurgical, mine, underground, tunnel toxic and harmful gas monitoring, industrial gas process analysis, and atmospheric environment quality analysis, etc. measurement field. Background technique [0002] Tunable semiconductor laser absorption spectroscopy (TDLAS) analysis method is a commonly used gas analysis method. It mainly uses the tunable and narrow linewidth characteristics of semiconductor lasers to measure by selecting a specific absorption spectrum line of the gas to be measured. Eliminate the interference of the spectrum of other gases, and realize the rapid online detection of the concentration of the gas to be measured. [0003] In some TDLAS laser gas monitoring applications, due to lightning protection, explosion protection or strong electromagnetic interference, the gas m...

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Problems solved by technology

[0003] In some TDLAS laser gas monitoring applications, due to lightning protection, explosion protection or strong electromagnetic interference, the gas monitoring point and the monitoring room must be connected through optical cables to transmit signals. Due to limited optical fiber resources, the number of gas monitoring points is large. , in the existing TDLAS monitoring system, each monitoring point needs to transmit and receive through at least 2 core optical fibers, and since the absorption wavelength of the measured gas at all monitoring points is exactly the same, it is impossible to improve the monitoring of single-core optical fiber through the wavelength division multiplexing system Point capacity, resulting in the number of monitoring points of the entire monitoring system being limited by the number of fiber cores of the optical cable

For example, in the coal mine gas monitoring application, the cable laying in the mine is far inferior to the optical fiber transmission in terms of distance and explosion-proof safety. The optical cable resources in the mine are extremely limited, and the number of monitoring points in the mine is very large, which limits this TDLAS-based technology. The use of gas monitors in mines

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