Adjustable laser absorption spectrum gas detection method based on software phase locking

The invention discloses an adjustable laser absorption spectrum gas detection method based on a software phase locking. The adjustable laser absorption spectrum gas detection method comprises the following steps: (1) generating a driving signal: generating a voltage signal by driving the simulated output end of an acquisition card through DAQ (Data Acquisition) of the internally-arranged acquisition card, and loading the signal to a DFB (Distributed Feed Back) laser driver to modulate DFB output laser; (2) absorbing and detecting gas: carrying gas concentration information by the modulated laser through a gas absorption tank, converting an optical signal into an electric signal by a photoelectric detector and acquiring the electric signal by the simulated input end of the acquisition card; and (3) carrying out software phase locking and demodulation: carrying out a software phase locking amplification filtering algorithm on acquired data and demodulating to obtain the gas concentration information. According to the method, large hardware phase locking amplification equipment is not used and only one data acquisition card and a software algorithm are used for carrying out the phase locking; the system structure is simple, the instrumentation and the portability are easy to realize and the system cost is reduced. The software phase filtering algorithm guarantees the demodulation precision and obtains a high-sensitivity gas detection result.