Dynamic range extension in imaging laser detection system
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摘要: 针对成像型激光探测系统动态范围不足的问题，以现有广角远心鱼眼透镜和CMOS摄像器件为硬件基础，提出通过图像处理的方法扩展系统动态范围。系统采用帧相减技术滤除背景干扰和噪声，进而进行激光光斑的识别和定位。在此基础上，针对接收激光能量的不同，提出采用不同方法扩展动态范围。当激光能量较低时，激光信号可能淹没在噪声中无法准确判读和精确定位，通过滤波技术排除噪声，提高图像信噪比，从而提高系统探测灵敏度，即扩展探测下限。对于探测上限，即当强激光入射时，由于鱼眼光学系统内会产生反射干扰光，有可能在成像面形成不规则的干扰光斑，通过光斑匹配模式识别的方法排除杂光干扰，提高识别上限。实验结果表明，该方法使系统动态范围从为70 dB提高到89 dB，提高近30%，有效扩大了探测系统的作用范围。Abstract: 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.
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Keywords:
- dynamic range /
- laser detection /
- imaging /
- noise filtering /
- matching recognition
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