Influence investigation on ranging performance for range-gated Geiger-mode avalanche photodiode ladar.

The ranging performance for Geiger-mode avalanche photodiode (Gm-APD) laser detection and ranging (ladar) is mainly evaluated by range accuracy and precision; although Gm-APD ladar can evaluate the ranging performance of the exact position, it is not helpful to comprehensively evaluate the influence on the ranging of each parameter in the whole gate. Due to the target echo's stochastic trigger making the delay adjustment inaccurate, the position of the echo in the gate is stochastic in the actual detection process, so the theoretical calculation may not be able to make ladar ranging performance clear. As to this question, based on the central limit theorem, and assuming the position of the target in the gate obeys Gaussian distribution, while also combining the Gm-APD triggering probability model, we propose the mean ranging accuracy and precision theory to objectively evaluate the ranging performance. At the same time, we combine the theory with the ladar ranging equation to investigate the effect of parameters such as laser transmitting energy, pulse width, gate width, target range, and noise intensity on ranging performance. The results show high transmitting energy, narrow gate width, short target range, and low noise intensity make mean ranging accuracy and precision low. The narrow pulse width will result in lower mean ranging accuracy and high mean ranging precision. Wide pulse width has the opposite effect; through comprehensive comparison, 10∼30   pulse width is more reasonable. According to theoretical analysis results, to achieve ladar's high ranging performance, we put forward concrete measures for improvement-reducing the gate width, enhancing laser energy, using a narrowband filter to reduce false alarm of noise, etc., consequently the research in this paper has significance for the Gm-APD ladar experimental parameter selection.