Method and device for improving laser gas analysis sensitivity based on nonlinear tuning

A nonlinear tuning, laser gas technology, used in the measurement of pressure or flow rate, temperature, gas concentration, can solve the problems of discarding, high technical requirements, unusable gas temperature, pressure and flow rate, etc., to improve accuracy and sensitivity Effect

Inactive Publication Date: 2014-02-26
TIANJIN UNIV
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  • Application Information

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Problems solved by technology

This method can simplify and optimize the measurement in theory, but it needs to accurately obtain and maintain the relative position of the peak of the absorption spectrum, any small temperature or injected current disturbance (noise) may have a greater impact, which in practice In addition, this detection method only records the line intensity information of the gas absorption spectrum, but discards the line shape information in the absorption spectrum. It can only be used for the measurement of gas concentration, and requires temperature and pressure make compensation
Cannot be used for the measurement of gas temperature, pressure and flow rate

Method used

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  • Method and device for improving laser gas analysis sensitivity based on nonlinear tuning
  • Method and device for improving laser gas analysis sensitivity based on nonlinear tuning
  • Method and device for improving laser gas analysis sensitivity based on nonlinear tuning

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Embodiment 1

[0101] Embodiment 1: (modulated absorption method of Gaussian function)

[0102] The following takes the analysis of the absorption spectrum of water molecules at 1395.514 nm as an example to illustrate the method and device for tunable laser absorption spectroscopy applying coordinate transformation. Consult the HITRAN database, you can get the absorption line intensity of the spectrum line is 5.93×10 -21 cm / molecule, the line width is 0.0505nm.

[0103] The tunable laser absorption spectrum analysis device for applying coordinate transformation of the present invention includes a laser driver 1, a diode laser 2, a signal generator 3, a photodetector 4, a preamplifier 5, a lock-in amplifier 6, an AD converter 7, a computer ( Or embedded processor) 8, light collimating lens 9 and 10; gas pool 11 and other parts, the principle of which is as follows figure 1 Shown. Among them, diode lasers, lock-in amplifiers, gas pools, and computers can use commercial instruments or modules.

[01...

Embodiment 2

[0124] Example 2: (Direct cosine absorption method)

[0125] The following still takes the analysis of the absorption spectrum of water molecules at 1395.514 nm as an example to illustrate the tunable laser absorption spectrum analysis method and device applying coordinate transformation. The tunable laser absorption spectrum analysis device for applying coordinate transformation of the present invention includes a laser driver 1, a diode laser 2, a signal generator 3, a photodetector 4, a preamplifier 5, an AD converter 7, a computer (or embedded processor) ) 8. The light collimating lens 9 and 10 and other parts, the composition principle is as follows Figure 4 Shown. Among them, diode lasers and computers can be commercialized instruments or modules.

[0126] The signal generator can use an arbitrary function generator that supports programming mode, or a specially designed signal generating circuit (module). In this embodiment, a specially designed signal generating circuit m...

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Abstract

The invention belongs to the technical field of measurement of concentration, temperature, pressure or flow speed of gas and provides a method and a device for improving the detection precision of a tunable laser absorption spectrum. Under a condition that the expense of system hardware is not increased, all pieces of information of spectral lines can be completely acquired and recorded, so that the measurement precision of a TDLAS (tunable diode laser absorption spectroscopy) system is improved; furthermore, the method and the device are suitable for on-line (in-situ) or off-line detection or monitoring application in the concentration, the pressure, the temperature and the flow speed of the gas. According to the technical scheme disclosed by the invention, a method for improving the laser gas analysis sensitivity based on nonlinear tuning comprises the steps of detecting the absorption spectrum of the gas to laser, and measuring parameters including the concentration, the pressure, the temperature and the flow speed of the gas, wherein certain transformation is applied in a laser excitation stage, and corresponding inverse transformation is applied in the stage of detecting the absorption spectral lines of the gas to the laser. The method and the device are mainly applied to gas detection.

Description

Technical field [0001] The invention belongs to the technical field of measurement of gas concentration, temperature, pressure or flow rate, and relates to a method and device for tunable diode laser absorption spectroscopy analysis, especially a modulation method and device for a tunable diode laser for trace gas detection. The invention It can be used for high-precision measurement of gas concentration, temperature, pressure or flow rate. Specifically, it relates to a method and device for improving the sensitivity of laser gas analysis based on nonlinear tuning. Background technique [0002] Tunable diode laser absorption spectroscopy (TDLAS) is a gas detection technology with high sensitivity, high resolution and fast response. It is widely used in gas monitoring in industrial processes, ambient atmosphere detection, and scientific research. field. It uses the wavelength tuning characteristics of diode lasers, that is, by changing the temperature or injection current of the ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G01N21/39G01D21/02
Inventor 杜振辉李金义刘翰蔚
Owner TIANJIN UNIV
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