APD光信号放大电路，相当有价值的电路图-APD optical signal amplification circuit, the circuit very valuable

激光测距，采用APD作为光电传感器接收反射激光，TDC-GP22进行时间测量，通过速度时间精确计算出距离(Laser ranging uses APD as photoelectric sensor to receive reflected laser, TDC-GP22 carries out time measurement, and calculates the distance by velocity and time accurately.)