当辐照光强较低时, CCD相机输出图像中的灰度值分布代表了辐照光的功率密度分布。利用此时CCD相机输出激光光斑的灰度分布及辐照激光功率计算了光斑中心像素上的平均激光功率密度。利用激光功率密度与激光功率成正比例的关系, 由实验测得的激光功率值获得了一系列中心像素上的激光功率密度值, 并利用示波器测量了相应的像素输出电压值, 得到了可见光CCD对1064 nm激光的响应曲线。由像素灰度值与激光功率密度值可知, 相机系统饱和即令像素灰度值达到最大的激光功率密度阈值约为0.11 mW/cm2; 而由CCD的光响应曲线可知, 令CCD芯片输出开始趋向于饱和的激光功率密度值约为0.20 mW/cm2。

When the irradiation light intensity is low, the gray value distribution of CCD camera output image represents power density distribution. Using the gray value distribution and the corresponding laser power, we calculated the laser power density on the centre pixel of laser facula area. Because laser power density is proportional to laser power, we got a series of power density value on the centre pixel of laser facula from the laser power measured in experiment. The corresponding pixel output voltage value was measured throgh oscillograph. And then we got the photoelectric response curve of CCD to 1064 nm laser. From the gray value and laser power density value, the approximate threshold value of laser intensity inducing CCD camera system saturation was 0.11 mW/cm2. And from the photoelectric response curve of CCD, the value causing CCD chip saturation was 0.20 mW/cm2.