基于相似测度算法的激光诱导薄膜损伤表面特征研究

鉴于薄膜激光损伤性能评价是增强抗激光红外观察窗口性能的重要保证，给出薄膜在脉冲激光诱导作用下的损伤表面特性及其机理。实验采用YAG脉冲激光器对TiO2薄膜样片进行1-on-1方式的激光诱导。通过CCD采集TiO2薄膜激光辐照前后2幅图像，将这2幅图像进行匹配，建立差异图像测度算法；实验得出TiO2薄膜样片的差异能量测度可判别出损伤情况，即测度值M＜0.1为未发生损伤，0.1＜M＜0.2为轻度损伤，0.2＜M＜0.5为中度损伤，M＞0.5为严重损伤。薄膜样片经过能量密度为0.5 J/cm2的激光辐照后粗糙度明显增大。研究结果表明，采用激光辐照前后图像匹配的测试方法可实现薄膜激光损伤与否的判别。

Surface characteristics study of laser-induced thin film damage based on similarity measure algorithm

The determination method of laser damage of thin film and the evaluation method of damage threshold are indispensable for enhancing anti-laser ability of infrared system observation window and its operating performance. The damage characteristics and mechanism of film by pulse laser induced damage were researched. The experiments used by YAG pulsed laser for TiO2 thin film were offered for 1-on-1 way of laser induced. By using the two images taken from charge coupled device (CCD) before and after laser illumination, the matching of the damaged image and the undamaged image was realized, and the difference image measure algorithm was established. The experiments conclude that the different energy measures of TiO2 thin film samples can identify the damage situation:the measure value M0.1, no damage; 0.1M 0.2, mild injuries;0.2M0.5, moderate damage; M0.5, serious injuries. The roughness of thin film samples irradiated by the laser with the energy density of 0.5 J/cm2 increases obviously. The results show that the method of image matching test before and after laser irradiation can realize discrimination of laser-induced film damage.