Enhancing the signal-to-noise ratio for laser ranging by adjusting the photon equivalent threshold of a multi-pixel photon counter

A photon equivalent (PE) threshold-adjusting regime for laser ranging is proposed based on a multi-pixel photon counter (MPPC), and the mechanism of PE threshold influence on the signal-to-noise ratio (SNR) is demonstrated and analysed. The unique PE threshold adjustability of an MPPC leads to interesting results for laser ranging. Experimental results show that the SNR of the laser ranging system is significantly improved by optimising the MPPC PE threshold, which is beneficial for detection and false alarm probabilities. Submillimeter laser ranging resolution is obtained with noncooperative targets placed several meters away. Nanosecond dead time single photon laser ranging without gating is obtained due to an MPPC with a small pixel area. Multiple target ranging is implemented with a single MPPC rather than an array.