Dynamic range extension in imaging laser detection system

To improve dynamic range in imaging laser detection system (ILDS), a method using image processing to extend the system dynamic range is proposed based on the existing hardware of wide-angle telecentric fisheye lens and complementary metal oxide semiconductor (CMOS) camera device. Frame subtraction technique is often used in ILDS to recognize and locate the laser spot by filtering out background interference and noise. The paper proposes that different methods should be used to expand the dynamic range corresponding to the received laser energy. When the laser energy is low, the laser signal that may be submerged in noise can not be accurately interpreted and precisely located. The technique of fuzzy weighted averaging filtering is used to remove noise and enhance detection sensitivity of the system, namely extension of the detection lower limit. When the incident laser is strong, the imaging surface may be interfered by stray light due to the reflection produced by the fisheye optical system. Spot matching pattern recognition method is presented to remove stray light and enhance the recognition upper limit. The experimental results show that these methods improve the system-s dynamic range from 70 dB to 89 dB.