The performance of passive photoelectric detection system for target detection is seriously affected by many factors,
such as the background light, the weather condition and the target temperature contrast, etc. To overcome the
disadvantages of the passive detection system, lots of domestic and foreign institutes are focusing on the research of the
laser active imaging detection system. Laser active imaging system based on range-gated technology use high peak
power laser pulse to illuminate the target, meanwhile use the receiving system with synchronization control circuit to
detect part of the reflected light from the target for imaging. It can efficiently suppress the brightness noise and the
backscattering noise, and apparently advance the imaging and identification performance for small dark target far away.
In this paper, on analyzing the principle of the range-gated laser active imaging technology, we studied the system range
performance limited by SNR thresholds due to the detector noise and the background noise respectively. By analyzing in
theory and simulation calculation, we made out the relationship between system range performance and other system
parameters in certain atmosphere conditions. The parameters include peak laser power, laser divergence angle, imaging
system resolution, target contrast, system SNR, etc.