为了建立有效无损的亚表面缺陷探测技术, 本文开展了光学元件亚表面缺陷的荧光成像技术研究, 通过系统优化激发波长、成像光谱、成像光路及探测器等影响探测精度和探测灵敏度的参数, 研制出小口径荧光缺陷检测样机。基于该样机对一系列精抛光熔石英和飞切KDP晶体元件的散射缺陷和荧光缺陷进行了表征, 获得了各类样品亚表面缺陷所占的比重差异很大, 从0.012%到1.1%不等。利用统计学方法分析了亚表面缺陷与损伤阈值的关系, 结果显示, 熔石英亚表面缺陷与损伤阈值相关曲线的R2值为0.907, KDP晶体亚表面缺陷与损伤阈值相关曲线的R2值为0.947, 均属于强相关。该研究结果可评价光学元件的加工质量, 用于指导紫外光学元件加工工艺, 并且由于该探测技术具有无损、快速的特点, 因此可应用于大口径紫外光学元件全口径亚表面缺陷探测, 具有极其重要的工程意义。

To establish an effective and nondestructive subsurface defects detection technology, the fluorescence image technique of optics subsurface defect was studied. A small-aperture fluorescent defect-detection prototype was developed by systematically optimizing various parameters such as the excitation wavelength, imaging spectrum, imaging light path, and the detector. Based on the prototype, the surface and subsurface fluorescence defects of the finishing processing of fused silica and diamond fly-cutting processing KDP were characterized. The laser-induced damage threshold was measured by a 351-nm nanosecond pulsed laser. There is a significant difference in the subsurface defects of various samples, ranging from 0.012% to 1.1%. The relationship between the subsurface defects and the damage threshold was analyzed by statistical methods. The results show that the R2 value of the fused silica subsurface defect and the damage threshold curve is 0.907, and the R2 value of the KDP crystal subsurface defect and the damage threshold correlation curve is 0.947; both are strongly related. The results can be used to evaluate the processing quality of the optical components.Because of its nondestructive and short duration characteristics, the technique can be applied to the detection of full-area subsurface defects in large-dimension UV optical components, which makes it vital in engineering.