Design and Implementation of Eye-Safe Band LiDAR System Based on Solid-State Photomultiplier for Kilometer-Range Applications

Light detection and ranging (LiDAR) technology is increasingly being applied to several fields, including defense surveillance and reconnaissance, where it is used to detect small objects at long ranges. In these scenarios, highly sensitive detection capabilities are essential, for which high-power lasers can be employed. In particular, the 1550-nm wavelength band offers the advantage of being eye safe, allowing for increased laser output. However, because increasing the laser output requires a larger system size and higher power consumption, this approach has inherent limitations. In this study, we implemented a small payload (<2 kg) LiDAR system based on a solid-state photomultiplier (SSPM), which has high sensitivity at 1550 nm. The experimental results demonstrated that the SSPM provides high sensitivity, detecting signals below −50.9 dBm with a low false alarm rate of 0.0014%. Although background light can potentially increase false alarms, this effect is mitigated by using optical filters. Therefore, the proposed detection scheme based on the SSPM can generate point cloud images without the need for complex postprocessing or calculations to mitigate speckle noise. We tested the feasibility of the SSPM as a high-sensitivity photodetector for the LiDAR system by designing and implementing a compact SSPM-based LiDAR system. The experimental results confirmed that an object with a reflectivity of 9% and located 801.22-m away could be detected using the proposed LiDAR system only with a peak power of 3.5 kW and receiver aperture diameter of 2 cm. Moreover, a kilometer-range (1145.71 m) image was successfully acquired using the proposed LiDAR system with the same parameters.