Design of Multi-Threshold Photon Detection System in Marine Lidar

With the improvement of the performance of photonic detection devices, lidar based on single-photon detector can improve the detection sensitivity to the photon level, which has gradually become the development trend of a new generation of lidar technology. To improve the performance of single-photon lidar system, a multi-threshold photon detection system suitable for marine lidar was designed in this paper, which realized the accurate identification and high-speed acquisition of single-photon pulse signals. The system includes hardware design and software design. The hardware design amplifies the input signal, feeds it into a comparator and compares it to the threshold voltage output of the AD5668 chip, and then transmits the LVDS signal generated by the comparison to the FPGA chip for processing. The software design includes an SPI control module and a clock shift acquisition module. The SPI control module controls the AD5668 to output a suitable threshold voltage for the comparator, and the clock shift acquisition module achieves a 1.6 GHz acquisition rate for the input signal. Finally, the photomultiplier tube was connected to the detection system, and the system function was tested, and the test results were in line with expectations.