Coherent differential absorption laser radar and method for detecting gas concentration

A laser radar, differential absorption technology, applied in measurement devices, analytical materials, re-radiation of electromagnetic waves, etc., can solve problems such as limitation and low quantum efficiency of photodetectors, and achieve high absorption cross-section coefficient, improved sensitivity, high-precision gas The effect of detection

Pending Publication Date: 2020-02-04
UNIV OF SCI & TECH OF CHINA
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Problems solved by technology

In the infrared band, due to the low quantum efficiency of photodetectors in existin

Method used

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  • Coherent differential absorption laser radar and method for detecting gas concentration
  • Coherent differential absorption laser radar and method for detecting gas concentration
  • Coherent differential absorption laser radar and method for detecting gas concentration

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Embodiment

[0050] A coherent differential absorption laser radar based on 3.0μm~10.6μm, including: adjustable continuous wave laser (1) and (2), beam splitter (3), acousto-optic modulator (AOM) (4), laser amplifier ( amplifier (5), circular (6), transmitting and receiving telescope (7), coupler (8), balanced detector (9), acquisition card (10), digital signal processing system (11); Tunable continuous wave lasers (1) and (2) are connected to the beam splitter (3). The beam splitter divides the laser into local oscillation light and outgoing laser. The outgoing laser is connected to the acousto-optic modulator (4); the acousto-optic modulator ( 4) Connect the laser amplifier (5), connect the laser amplifier (5) to the circulator (6), connect the circulator (6) to the transmitting and receiving telescope (7), and connect the signal from the transmitting and receiving telescope (7) to the circulator (6). Coupler (8), coupler (8) connected to balanced detector (9), balanced detector (9) conne...

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Abstract

The invention provides a coherent differential absorption laser radar comprising a first tunable continuous wave laser, a second tunable continuous wave laser, a beam splitter, an acousto-optic modulator, a laser amplifier, a circulator, a transmitting and receiving telescope, a coupler, a balance detector, an acquisition card and a digital signal processing system. Two required laser wavelengthsare determined by selecting appropriate absorption lines of gas molecules to be tested in intermediate infrared, then local oscillation light and signal light are split by the beam splitter, frequencies are finally combined by the coupler, and the balance detector is used for detection to obtain a concentration of the gas molecules. Due to the larger gas absorption cross-section coefficient and lower background radiation of the intermediate infrared, the detection sensitivity is improved. The use of coherent detection instead of direct detection reduces the influence of low quantum efficiencyon the precision of detection, improves the utilization of echo signals, and improves the performance of the differential absorption laser radar.

Description

Technical field [0001] The present invention relates to the technical field of laser radar, in particular to a coherent differential absorption laser radar and a method for detecting gas concentration. Background technique [0002] Lidar technology has received widespread attention since the birth of lasers, and has been used in military, meteorological and atmospheric monitoring with its strong anti-interference ability and high precision. Lidars with different structures and different uses continue to emerge. Differential absorption radar is an important application of lidar. Currently, differential absorption radar is used in many aspects such as air pollutant monitoring. [0003] Most gas molecules have their own characteristic absorption lines, and the dark lines left in the spectrum due to the selective absorption of gas molecules are absorption lines. Differential absorption lidar detects atmospheric pollution by selecting the wavelength of the characteristic absorption li...

Claims

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Application Information

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IPC IPC(8): G01S7/481G01S17/88G01N21/3504
CPCG01S7/481G01S17/88G01N21/3504
Inventor 吴云斌王冲夏海云窦贤康
Owner UNIV OF SCI & TECH OF CHINA
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