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Coherent laser radar and water flow velocity detection method

A technology of laser radar and detection method, which is applied to measurement devices, radio wave measurement systems, and re-radiation of electromagnetic waves, etc., can solve problems such as poor stability, high surface accuracy requirements, and unfavorable coherent detection, and achieves strong stability and structure. Compact, highly integrated effects

Active Publication Date: 2020-06-09
XIAMEN UNIV
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  • Application Information

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Problems solved by technology

[0008] However, when short-wavelength visible light band lasers are used for coherent detection, the accuracy of the surface type is high, and the spatial optical path is easily affected by changes in ambient temperature, pressure and humidity, and the stability is poor. Therefore, short-wavelength lasers are not conducive to coherent detection.
[0009] This has just caused in the prior art, so far no one has proposed the idea of ​​detecting ocean current or current velocity by coherent detection method

Method used

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Embodiment 1

[0048] see figure 1 , figure 1 The structure of the coherent lidar 100 in the first embodiment is shown. Such as figure 1 As shown, the coherent lidar 100 of this embodiment includes a first laser 1, a first beam splitter 2, a second laser 3, a second beam splitter 4, a pulse modulation module 5, a transmitting and receiving module 6, a first wavelength division Multiplexer 7 , second wavelength division multiplexer 8 , frequency conversion module 9 , 3dB beam splitter 10 , coherent detector 11 and data processing module 12 .

[0049] Wherein, the first laser device 1 generates the first laser, where the wavelength of the first laser is located in the wave band with strong water penetrating ability, and the wave band with strong water penetrating ability includes ultraviolet wave band, visible light wave band and Near-infrared band, preferably visible light band. The first laser is a continuous laser. The first laser 1 has the characteristics of low RIN noise, narrow line...

Embodiment 2

[0081] see figure 2 , figure 2 The coherent lidar 100 in the second embodiment is shown. Such as figure 2 As shown, the only difference between the second embodiment and the first embodiment lies in the transmitting and receiving module 6 of the coherent lidar 100 . In the second embodiment, the transmitting and receiving module 6 adopts a coaxial transmitting and receiving structure, which includes a circulator 63 and a transmitting and receiving telescope 64 .

[0082] Wherein, the first channel is formed between the a-end and the b-end of the circulator 63 ; the second channel is formed between the b-end and the c-end of the circulator 63 . The first passage of circulator 63 is connected with the output end of amplifier 53 and transceiver telescope 64, is used to receive the detection signal that amplifier 53 sends, and sends to transceiver telescope 64; The second passage of circulator 63 is connected with transceiver telescope 64 and the second The second input end...

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Abstract

The invention discloses a coherent laser radar and a water flow velocity detection method. The invention provides a water flow velocity coherent detection technical scheme based on frequency down-conversion. The method comprises the following steps: detecting water flow and turbulence of each water layer by adopting visible light band laser with penetrating power to the water flow to obtain an echo signal; mixing the local oscillator signal and the echo signal with the pump laser, and performing frequency down-conversion by using a nonlinear waveguide to obtain a near-infrared band or infraredband to-be-detected signal which is easy for coherent detection so as to perform coherent beat frequency. The technical scheme disclosed by the invention can be used for finely detecting the water flow velocity of each water layer and the turbulent flow velocity in the vertical direction, so that the integration level of the system can be improved, and the system can be conveniently carried on various platforms.

Description

technical field [0001] The invention relates to the field of laser radar, in particular to a coherent laser radar and a water flow velocity detection method. Background technique [0002] Ocean currents, also known as ocean currents, are water masses of different densities formed by seawater due to thermal radiation, evaporation, precipitation, and cold shrinkage, coupled with wind stress, geostrophic deflection force, and tidal force. It is a large-scale and relatively stable flow. One of the universal movement forms of seawater, the direction and speed of ocean current movement in each water layer are important parameters of oceanography. The movement of ocean currents is closely related to maritime security, ocean engineering, and ocean warfare. [0003] Traditional sea surface current measurement methods include on-site observation, stereo photography and radar detection. On-site observations can obtain data in a small area within a certain period of time, which cannot...

Claims

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Application Information

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IPC IPC(8): G01S7/481G01S17/58G01S17/88
CPCG01S7/481G01S17/58G01S17/88
Inventor 上官明佳李忠平商少凌
Owner XIAMEN UNIV
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