Coherent laser radar for improving detection range by adopting optical phase-lock technology

Abstract

The invention discloses a coherent laser radar for improving detection range by adopting an optical phase-lock technology. The coherent laser radar comprises a main laser device (space coupling), a tunable local oscillator laser, a receiving optical system, a 3dB coupler, a balanced detector, a frequency and phase discrimination module (PFD), a charge pump and a loop filter. A beat frequency signal is obtained after the laser emitted by the main laser device is interfered by an echo signal reflected by a target and local oscillator light, phase difference of two signals can be obtained after the beat frequency signal and a set reference signal are subjected to the frequency and phase discrimination module, the frequency of the local oscillator laser device is regulated and controlled through the corresponding control voltage produced by the loop filter, so that the beat frequency signal can be locked to the set reference signal phase, the beat frequency signal meets a condition of timedomain coherent accumulation, the extraction of the weak signal is more facilitated, and the detection range of the coherent laser radar is finally improved.

Description

technical field [0001] The invention belongs to the technical field of coherent laser radar, and in particular relates to a coherent laser radar which adopts optical phase-locking technology to improve detection distance. Background technique [0002] In the coherent laser radar, the echo signal light interferes with the local oscillator light to generate a beat frequency signal, and the echo signal is extracted by using the local oscillator gain, which greatly improves the detection sensitivity and the working distance of the laser radar. In order to further improve the detection sensitivity, it can be used for The beat frequency signals are coherently accumulated. [0003] At present, coherent accumulation in frequency domain is often used, and it has been developed relatively maturely. The present invention considers coherent accumulation in time domain on this basis to further improve detection sensitivity. However, due to the influence of the phase noise of the laser i...

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Problems solved by technology

However, due to the influence of the phase noise of the laser itself, platform vibration, atmospheric disturbance, and Doppler frequency shift during the signal optical transmission process, the phase of the beat frequency signal is jittered. At this time, the echo signal is coherently accumulated in the time domain. Can not improve the signal-to-noise ratio of the echo signal

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