Trace gas concentration detection device

Abstract

The utility model discloses a trace gas concentration detection device, solves the problem that the existing trace gas concentration signal extraction is not accurate enough, and belongs to the field of weak signal detection. According to the invention, an arbitrary waveform generation module is constructed by using an FPGA internal digital circuit, and reference signals required by a digital signal processing module and driving signals required by a laser driving source are generated by the arbitrary waveform generation module. The frequency of an input signal which is sent into the digital signal processing module and contains trace gas information is ensured to be consistent with the frequency of a reference signal to the greatest extent, and accurate gas concentration information is obtained. A dual-channel phase frequency lock-in amplifier constructed by a digital signal processing module in an FPGA is used for respectively squaring two paths of difference frequency signals with phase information generated by dual channels through a multiplier, the two paths of signals are added, and amplitude information with a phase error of 0 is obtained through root extraction; and the influence caused by the phase error of the detected signal and the reference signal is avoided.

Description

technical field [0001] The invention relates to a trace gas concentration detection device, which belongs to the field of weak signal detection. Background technique [0002] Tunable semiconductor laser absorption spectroscopy technology is widely used as a detection technology for weak gases. Since the molecular vibration or rotation frequencies produced by different gas molecules are different, when the laser frequency emitted by the laser is consistent with the vibration or rotation frequency of the specific gas molecules to be detected At the same time, the light energy of this wavelength will be absorbed by specific molecules, thereby attenuating the light intensity of the incident laser light. Finally, the attenuated light intensity signal is processed by photoelectric conversion, and then through the signal conditioning circuit and digital signal processing circuit to obtain specific amplitude information, and then compare the input and output light intensity changes ...

AI Technical Summary

Problems solved by technology

[0004] Aiming at the problem that the existing trace gas concentration signal extraction is not accurate enough, the present invention provides a trace gas concentration detection device