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Sine wave modulation-based high-sensitivity laser methane measuring device and method thereof

A sine wave modulation and high-sensitivity technology, applied in the field of laser spectroscopy, can solve the problems of large volume and increased cost of lasers, and achieve the effects of improving signal-to-noise ratio, improving detection sensitivity, and reducing background noise

Inactive Publication Date: 2016-04-27
安徽中科瀚海光电技术发展有限公司
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Problems solved by technology

In addition to the greatly increased cost of such lasers, their volume is relatively often larger

Method used

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  • Sine wave modulation-based high-sensitivity laser methane measuring device and method thereof
  • Sine wave modulation-based high-sensitivity laser methane measuring device and method thereof
  • Sine wave modulation-based high-sensitivity laser methane measuring device and method thereof

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Embodiment Construction

[0033] like Figure 7 As shown, a high-sensitivity laser methane concentration measurement device based on sine wave modulation includes a semiconductor laser 1, a photodetector 3, a preamplifier circuit 4, a filter amplifier circuit 5, a high-speed high-bit AD acquisition module 6, and a DSP processor 7. DA conversion module 8 and laser driver module 9; the IO port of DSP processor 7 is connected to the control port of DA conversion module 8, the output end of DA conversion module 8 is connected to the input end of laser driver module 9, the laser driver module 9 The current output terminal is connected to the LD pin of the semiconductor laser 1, and the laser light emitted by the semiconductor laser 1 passes through the air mass 2 to be measured and is received by the photodetector 3, and the output signal of the photodetector 3 is connected to the input terminal of the low-noise preamplifier circuit 4 , the program-controlled port of the low-noise preamplifier circuit 4 is ...

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Abstract

The invention discloses a sine wave modulation-based high-sensitivity laser methane measuring device and a method thereof. Sine wave modulation is carried out on wavelength of a semiconductor laser; by the utilization of a low noise pre-amplification circuit, a photo-signal is converted to a low-noise voltage signal, filtering and amplification are also carried out, then low-distortion data acquisition is carried out on the signal by a high-speed high-order ADC, and the emphasis is to carry out phase-shift self-addition algorithm on the signal by the use of a DSP processor so as to raise absorption signal amplitude and eliminate influence of sine wave carrier; and finally, second harmonic intensity is obtained through FFT transformation, and back calculation of methane gas concentration is achieved by combination of parameters such as sine wave peak value, etc. On the basis of not increasing hardware cost, detection sensitivity of a laser methane gas detection system is greatly raised through algorithm.

Description

technical field [0001] The invention relates to the field of laser spectroscopy and gas detection technology, in particular to a high-sensitivity laser methane concentration measurement device and method based on sine wave modulation. Background technique [0002] The detection of dangerous gases has become the basic guarantee for modern residents' life, industrial production and national security. [0003] With the improvement of semiconductor laser manufacturing process and the reduction of cost, gas absorption spectroscopy measurement technology based on semiconductor laser has become the key development direction of modern gas detection technology. This technology utilizes the absorption characteristics of gas molecules on the laser spectrum, and has the advantages of high precision, fast response, strong anti-gas interference and non-contact measurement. However, in practical applications, due to the limitation of the measurement optical path and the interference of ci...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G01N21/39
CPCG01N21/39
Inventor 李幼安宁小玲
Owner 安徽中科瀚海光电技术发展有限公司
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