Wavelength-changing tunable diode laser absorption spectrum gas detection device and method

Abstract

The invention discloses a wavelength-changing tunable diode laser absorption spectrum gas detection device and method. The device comprises a laser, a circulator, a reflective probe, a photoelectric detector and a data conversion unit, wherein the laser outputs an optical signal of which the wavelength and light intensity change along a drive current cycle when excited, the optical signal is transmitted to the circulator, and the circulator receives the optical signal of the laser and transmits the optical signal to the reflective probe; the reflective probe contains an open light path with asection of fixed distance, so that interaction between the optical signal and tested gases is realized; and the optical signal returned by the reflective probe is transmitted to the photoelectric detector, and the optical signal is converted into a weak current analog signal to be output to the data conversion unit so as to obtain the tested gas concentration value. The light intensity change andwavelength change in each cycle are divided into two stages. A second light intensity change stage in which the wavelength covers a tested gas absorption line is compensated by utilizing a first lightintensity change stage in which the wavelength the far away from the tested gas absorption line, and the measurement accuracy and long-term stability are improved.

Description

technical field [0001] The invention relates to a wavelength-agile tunable semiconductor laser absorption spectrum gas detection device and method. Background technique [0002] In the field of fiber optic gas detection, spectral absorption method is the most common detection technology. This method uses the attenuation of light intensity of specific wavelengths transmitted or reflected in the gas to detect the concentration of the gas. Each gas has its own characteristic absorption line. When the light wavelength emitted by the light source coincides with the absorption line of the gas, light absorption will occur, and the light intensity will be attenuated to a certain extent. The attenuation is related to the concentration of the gas. . [0003] When a beam of light intensity is I 0 When the parallel light passes through the gas chamber containing the gas to be measured, if the optical signal covers the absorption line of the gas to be measured, the transmitted or refl...

AI Technical Summary

Problems solved by technology

[0011] However, TDLAS technology focuses on the impact of light source wavelength drift and measured gas absorption line changes on detection accuracy.

Random factors such as the power stability of the light source, the change of the coupling state at the coupling point of the optical signal link, and the drift of the photoelectric device index will also cause the intensity of the measured optical signal to change, which seriously affects the accuracy of the measurement.

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