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Tunable diode laser absorption signal time-frequency conversion method

A diode laser and frequency conversion technology, which is applied in the field of laser diagnosis and measurement, can solve the problems of different refractive index and inapplicability, and achieve the effect of simple operation, high precision and low cost

Pending Publication Date: 2022-08-09
SOUTH CHINA UNIV OF TECH
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  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

However, the traditional laser frequency measurement method has the following shortcomings: (1) The high-precision etalon will be affected by environmental disturbances and system noise during the measurement process, and the accuracy of the peak-finding algorithm is one of the reasons that affect the accuracy of time-frequency conversion; (2) The refractive index of the etalon is different for different frequency lasers, so the refractive index needs to be recalculated every time the calibration frequency is changed, and different wave bands require different material etalons
However, existing experimental methods are not applicable when only one molecular absorption peak exists within the laser scanning range

Method used

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  • Tunable diode laser absorption signal time-frequency conversion method
  • Tunable diode laser absorption signal time-frequency conversion method
  • Tunable diode laser absorption signal time-frequency conversion method

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Experimental program
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Embodiment

[0037] like figure 1 As shown, a tunable diode laser absorption signal time-frequency conversion method is applied to a single-line TDLAS measurement spectrum, including:

[0038] S1 builds a wavelength scanning-direct absorption spectrum measurement system to collect the transmission signal of the wavelength etalon and the measured absorption signal of the gas to be measured, and the absorption signal has only one absorption peak.

[0039] further, as figure 2 As shown, the wavelength scanning-direct absorption spectroscopy measurement system includes a function generator, a near-infrared tunable semiconductor laser, an F-P etalon, a standard concentration gas cell and a data acquisition module.

[0040] Specifically, methane was selected as the measured gas in the experiment, and a gas cell with a certain concentration of CH was continuously introduced into the gas cell made of quartz glass tubes. 4 Standard gas. The function generator is used to generate a sawtooth wave...

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Abstract

The invention discloses a tunable diode laser absorption signal time-frequency conversion method, which comprises the following steps: constructing a wavelength scanning-direct absorption spectrum measurement system, and collecting a wavelength etalon transmission signal and an actually measured absorption signal of a measured gas, the absorption signal having only one absorption peak; comparing the actually measured absorption signal with a database theoretical spectrum, and extracting feature points of the actually measured absorption signal and the database theoretical spectrum; obtaining a sampling point-wave number corresponding graph according to the extracted feature points, and establishing a time-frequency conversion model of a time domain and a frequency domain in the TDLAS; and comparing the time-frequency conversion model with a wavenumber calibration result, and verifying the accuracy of the time-frequency conversion model. The method provided by the invention has the characteristics of high precision, simplicity in operation and the like, has great application potential in low-cost TDLAS (tunable diode laser absorption spectroscopy) application, and plays an important role in deeply knowing the dynamic wavelength tuning characteristic of a laser.

Description

technical field [0001] The invention relates to the technical field of laser diagnosis and measurement, in particular to a time-frequency conversion method for a tunable diode laser absorption signal. Background technique [0002] Tunable Laser Absorption Spectroscopy (TDLAS) is an optical method for rapid gas detection by detecting an isolated absorption line of absorbing molecules by utilizing the narrow linewidth and fast tuning characteristics of semiconductor lasers. In practical applications, the abscissa of the detection signal obtained by the TDLAS system is generally the number of sampling points at equal time intervals, corresponding to the time series. The normalization of the line area is only valid in the frequency domain, and the abscissa of the spectrum needs to be converted into wavenumber (cm). -1 ) can be used to solve the integrated absorbance value, and the accuracy of time-frequency conversion plays an important role in the inversion accuracy of flow fi...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G01N21/39
CPCG01N21/39
Inventor 董美蓉蔺潇聂伟饶刚福陆继东
Owner SOUTH CHINA UNIV OF TECH
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