比较了高通量密度下损伤点分别位于上游介质的前后表面时热像的位置及峰值光强的区别。讨论了热像交替排布的现象及峰值光强随损伤点尺寸的变化规律。针对上游光学元件中的损伤点是诱发后续光路中热像的主要因素, 提出了以损伤点经一定传输距离后引起的衍射环图像为分析对象的热像预判技术。该技术运用高信噪比的梯度方向匹配算法来获取衍射环图像的特征信息, 进而反演出衍射距离和损伤点尺寸。利用液晶空间光调制器产生的单个等效损伤点的衍射图像证明了该方法的有效性; 并采用光学元件上实际存在的损伤点所引起的衍射环图像分析了该算法反演多个损伤点时抑制噪声干扰的能力及其空间分辨率。

The locations and peak intensities of hot images are compared under high flux density when the damage point is located on the front surface and rear surface of upstream medium respectively. The phenomenon of alternate arrangement of hot images and variation rule of peak intensities with damage point size are discussed. For the fact that the damage point in upstream optical components is the major factor to induce hot images in subsequent optical path, the hot images prejudging technique is proposed, and the analysis object of which is diffraction rings image introduced by damage point propagation for a certain distance. This technique extracts the feature information of diffraction ring images by using gradient direction matching method with high signal-to-noise ratio and then calculates the diffraction distance and the size of damage point inversely. The diffraction images of single equivalent damage point produced by liquid crystal spatial light modulator is used to demonstrate the effectiveness of the proposed method. The capability of suppressing noise interference and its spatial resolution are analyzed by using the diffraction ring images caused by the actual damage point on the optical components, when multi-damage points are inversed by the proposed method.