Time-division-multiplexing polarized coherent Doppler wind-finding laser radar

Abstract

The invention discloses a time-division-multiplexing polarized coherent Doppler wind-finding laser radar comprising a continuous wave laser, an optical fiber splitter, an optical modulator, a transmitting telescope, a receiving telescope, a polarization splitting element, a polarization-maintaining time-delay element, a fast and slow axis conversion element, a photoelectric switch, a coupler, a photodetector, a data acquisition card and a digital signal processing module. The fast and slow axis conversion element converts S polarization-state signal light into a P polarization-state signal light; and beating with different polarization-state echo signals can be realized only by one single P polarization-state local isolator light. With the polarization-maintaining time-delay fiber, signals with different polarization states are separated in a time domain, so that one photodetector can detect different polarization-state echo signals; and compared with the way of detecting different polarization-state mixed signals by using two photodetectors, the way employed by the polarized coherent Doppler wind-finding laser radar enables the error caused by different responses of the detectors to be reduced, so that the receiver system of the laser radar can be simplified.

Description

technical field [0001] The invention relates to lidar technology, in particular to a polarization coherent Doppler wind-measuring lidar with time division multiplexing. Background technique [0002] Accurate atmospheric wind field measurement is of great significance for detecting atmospheric pollution, obtaining military environmental intelligence, improving aerospace safety, improving the accuracy of weather forecasts, and improving climate models. Wind lidar is an effective means of wind field measurement, which can be divided into direct detection wind lidar and coherent detection wind lidar. The direct detection wind measurement lidar uses an optical discriminator to convert the Doppler frequency shift information into the relative change of energy, and realizes the measurement of the atmospheric wind field; the coherent detection wind measurement lidar uses the coherence between the atmospheric echo signal and the local oscillator laser The beat frequency realizes the...

AI Technical Summary

Problems solved by technology

[0009] (1) In the coherent wind lidar system, one of the necessary conditions for coherent beat frequency is that the signal light and the local oscillator light are in the same polarization state, but due to the aerosol depolarization effect, the echo signal is no longer linearly polarized light, As a result, the polarization state of part of the echo signal of the traditional coherent wind lidar is different from that of the local oscillator laser, resulting in the loss of the echo signal

[0010] (2) Because the depolarization ratio is related to the aerosol situation, the traditional coherent wind lidar signal cannot reflect the aerosol situation

Images