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Heterodyne balance detection system and detection method applied to TDLAS direct absorption method with low SNR

A low signal-to-noise ratio, balanced detection technology, applied in measurement devices, color/spectral characteristic measurement, material analysis by optical means, etc., can solve the problem of difficult adaptive adjustment of reference light, achieve simple demodulation and eliminate interference , the effect of preventing distortion

Active Publication Date: 2019-04-30
NANJING SCIYON AUTOMATION GRP
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Problems solved by technology

However, in actual industrial applications, because the detection signal changes in real time and the attenuation is often greater than 1000 times, it is difficult to adjust the reference light adaptively

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  • Heterodyne balance detection system and detection method applied to TDLAS direct absorption method with low SNR
  • Heterodyne balance detection system and detection method applied to TDLAS direct absorption method with low SNR
  • Heterodyne balance detection system and detection method applied to TDLAS direct absorption method with low SNR

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Embodiment Construction

[0024] The present invention will be further described below in conjunction with the accompanying drawings.

[0025] Such as Figure 1 to Figure 4 , the present invention is a heterodyne balanced detection system applied to TDLAS direct absorption method under low signal-to-noise ratio, including DFB laser 1, 1×2 single-mode fiber beam splitter 2, collimator 3, space to be measured 4, Multimode noise scrambler 5, single-mode fiber time delayer 6, 2×2 multimode fiber splitter 7, multimode fiber time delayer 8, multimode fiber attenuator 9, balance detector 10 and single-mode fiber Attenuator 11, two collimators 3 are respectively placed on both sides of the space to be measured 4, and the collimator 3 on one side forms the transmitting end, and the collimator 3 on the other side forms the receiving end; the DFB laser The output laser of 1 is transmitted by optical fiber to the input port of 1×2 single-mode fiber splitter 2, and the two output pigtails of 1×2 single-mode fiber ...

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Abstract

The invention discloses a heterodyne balance detection system and detection method applied to a TDLAS direct absorption method with low SNR. A modulation signal outputted by a DFB laser is split intoprobe light and reference light by a 1*2 single mode fiber splitter, the probe light is attenuated drastically through the to-be-tested environment, the two beams are made by a single mode fiber timedelay device to generate phase difference, the probe light is further subjected to multimode noise elimination through a multimode noise scrambler, heterodyne interference is formed in a 2*2 multimode fiber splitter, after heterodyne interference, the signal is 1:1 split and accessed to a balance detector, and an amplified interference signal after detector noise reduction is obtained. The methodis advantaged in that the probe light and the reference light are subjected to interference in the 1*2 single mode fiber splitter and are uniformly outputted in the 2*2 multimode fiber splitter, DC volumes of the two output signals are made to be the same regardless of whether the detection light fluctuates or not, the signals are accessed to the balance detector to realize balanced noise immunity, and real-time performance and anti-noise ability are improved significantly.

Description

Technical field: [0001] The invention relates to a heterodyne balance detection system and detection method applied to the TDLAS direct absorption method under low signal-to-noise ratio. Background technique: [0002] Tunable Diode Laser Absorption Spectroscopy (TDLAS) is a new type of optical sensor based on laser principle, which is applied to the non-contact measurement of gas concentration and temperature in various environments. Its high-speed feedback and real-time monitoring characteristics make it one of the most important measurement methods in dynamic process control systems. [0003] Direct absorption method (DAS) is a data processing method in TDLAS technology, which is applied in the environment with strong absorption intensity. The two-line exemption from calibration and the need for approximate calculations are advantages over the WMS wavelength modulation method. The biggest disadvantage of DAS is its poor anti-interference ability, low signal-to-noise rati...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G01N21/39G01N21/01
CPCG01N21/01G01N21/39
Inventor 沈德明赖小明陈昊邹婷
Owner NANJING SCIYON AUTOMATION GRP
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