相位法激光测距接收系统

相位法激光测距作为一种高精度的测距方法，在很多领域中得到广泛应用，在激光调制频率一定的情况下，测距速度和精度取决于相位差测量的速度和精度，并受信号串扰等因素的影响。基于此，提出了一种新的相位差放大测量的方法，在不增加测量时间的同时将测相精度提高1/N倍，并结合欠采样技术避免了混频器和其他多余器件的使用，减小了串扰对系统的影响；高频弱光信号入射到雪崩光电二极管上，会在输出信号上产生相位延迟导致测距误差，我们提出灵活控制加在雪崩光电二极管上的反向偏压的方法减小该相位延迟，对于调制频率为18.5MHz波长为650nm的激光，当入射光强度为0.5uW时，可将相位延迟从1.4度 压缩到0.03度 之内；建立了信号串扰产生测相误差的数学模型，并通过实验给出了采取不同屏蔽措施时串扰对测相误差的影响。实验结果证明，当调制频率为18.5MHz时，测相精度为0.014度 ，相应测距精度可达0.3mm 。

Phase-shift laser range finder receiver system

Phase shift laser range finding is widely used in many fields with its high measurement resolution. Measuring rate and resolution of the whole range finding system is determined by those of phase shift detecting and is influenced by the crosstalk for a given modulation frequency. Based on these, a new magnification of phase shift detecting is proposed which improves the measurement resolution 1/N times without increasing the measuring time. The under sampled technique is adopted to perform multi-frequency modulation in the same system which avoids using the mixer and other accessorial components. These reduce prior art scheme complexities and the influence of crosstalk. Week light with high frequency is incident on the avalanche diode (APD), the phase of the output signal from APD is delayed over that of the incident light which induces distance measurement error. A new method on suppressing the phase delay is presented by controlling the bias voltage acting on APD. For a modulation frequency of 18.5MHz, a wavelength of 650nm and incident light intensity of 0.5uW, the phase delay of 1.4o can be reduce to less than0.03o .The crosstalk mathematic model is set up. The crosstalk influences on phase shift measurement employing different electrostatic screen are given. The experiment results show that the phase shift measurement resolution is 0.014o and the distance measurement resolution is 0.3mm accordingly when the modulation is 18.5MHz.