Photoelectric Sensor Circuit For Linear Detector Array Lidar

Three-dimensional imaging Lidar mainly consists of three different types sorted by scanning method which are two-dimensional scanning with a single detector, non-staring scanning with detector array and one-dimensional detecting with linear detector array. All the echo of the first type of Lidar is received by a single detector. As a result,the distance data and echo-strength data can only be achieved once at a time. The complete data of the model is synthesized with two-dimensional opto-mechanic scanning,which is rather mature currently but low imaging speed,bulky and power-wasting. As for the non-staring scanning system mentioned above, all the data is achieved at a time with detector array and no more scanning mechanism is necessary. This scanning method is high in imaging speed and compact in size but highly restricted in high-resolution or large-view application due to the volume of every unit and read-out circuit. Linear array may get data in a row(column)of the scanned target at first,then data accumulates with Lidar scanning in arc or circle. The imaging rate is even faster than the single-detector scanning. In conclusion, one-dimensional detecting with linear detector array is rather superior and potential in the Lidar field. The experiment has been done to test the performance of the system.This paper presents the imaging principal of three-dimensional Lidar. The hardware implementation is based on system parameters which mainly focuses on APD read-out circuit, low-noise power supply and laser-synchronized scanning method with the output of PIN detector. The implementation can work well from laser-pulse reception to conversion to voltage signal. Meanwhile, TTL output from PIN detector is transformed to drive a turntable on which the Lidar is fixed to realize synchronical scanning. An transimpedance amplifier named LMH6629 plays the role of Ⅰ-Ⅴ transformation in APD read-out circuit which features low noise voltage and low input offset current. The capacitor in the circuit realizes phase-compensation. Both LDO and buck converter are included in the power implementation which improve efficiency and reduce ripple current.It can supply current for 64 APDs at most. The TTL output of the PIN detector is transformed to a wide pulse.The motor driver used in synchronical scanning implementation is SH2014A with an accuracy up to 0.0003125° and realize the synchronization of laser pulse and motor. Finally, the performance of the hardware system is verified by experiments.