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Gas monitoring method and apparatus based on quasi continuous diode laser modulated spectrum

A diode laser and diode laser technology, applied in the direction of color/spectral characteristic measurement, etc., can solve problems such as interference and measurement errors, and achieve the effect of improving sensitivity and expanding the working temperature range

Inactive Publication Date: 2009-05-20
TIANJIN UNIV
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Problems solved by technology

When the absorption of the incident light by the gas is small, the transmitted light intensity is very strong, and the relative change of the light intensity is very small, so it is easily disturbed by the background noise, causing measurement errors

Method used

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  • Gas monitoring method and apparatus based on quasi continuous diode laser modulated spectrum
  • Gas monitoring method and apparatus based on quasi continuous diode laser modulated spectrum
  • Gas monitoring method and apparatus based on quasi continuous diode laser modulated spectrum

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Embodiment Construction

[0027] When quasi-CW lasers are used as light sources for trace gas detection, direct detection (or gating technology) is usually used, and the method of applying wavelength modulation technology to quasi-CW lasers has not been reported. In order to improve detection sensitivity, it will be of great significance to apply wavelength modulation technology to quasi-CW lasers.

[0028] The invention relates to a quasi-continuous diode laser modulation spectrum method for gas detection, which includes providing a high-frequency modulation signal by a modulation signal generator, and the modulation signal is superimposed on the pulse wave with high-frequency sinusoidal disturbance and low-frequency sawtooth wave sweep The modulation signal can also be a low-frequency sawtooth wave sweep signal directly superimposed on the pulse wave. Provide this modulation signal to the laser driver to control the injection current of the laser. The laser emits a certain wavelength range of laser l...

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Abstract

The invention relates to a method and a device for detecting gas, in particular to a modulation spectrum gas detection method based on quasi-continuous diode laser, and a device thereof. The invention adopts a technical proposal that a quasi-continuous diode laser spectrum modulation method for gas detection comprises the following steps: a modulation signal generator outputs a modulation signal and a reference signal; the modulation signal is supplied to a laser driver for controlling the injection current of a quasi-continuous diode laser; the reference signal is supplied to a lock-in amplifier and used as the reference signal; laser emitted by the quasi-continuous diode laser passes through to-be-detected gas and then is received by a photodetector; the output of the photodetector is transmitted to a preamplifier, amplified and then sent into the lock-in amplifier; and output signals of the lock-in amplifier are sent into a computer via an AD converter, processed and analyzed, so as to obtain the species and concentration data of the detected gas. The method is mainly applied to occasions needing trace gas detection with high sensitivity and high resolution.

Description

technical field [0001] The present invention relates to a method and device for detecting gas, in particular to a method and device with high sensitivity and high resolution which can be used for trace gas detection, in particular to a gas detection method and device based on quasi-continuous diode laser modulation spectrum. Background technique [0002] Tunable diode laser absorption spectroscopy technology is a detection technology with high sensitivity, high resolution and fast response. It is widely used in industrial gas monitoring and environmental atmospheric monitoring and other fields. It uses the wavelength tuning characteristics of diode lasers, that is, by changing the temperature or injection current of the diode laser, the output wavelength of the laser is changed. Obtain the absorption spectrum of the characteristic absorption line of the selected gas to be measured within the wavelength tuning range, so as to perform qualitative or quantitative analysis of th...

Claims

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Application Information

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IPC IPC(8): G01N21/39
Inventor 杜振辉翟雅琼徐可欣
Owner TIANJIN UNIV
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