Experimental investigation of subsurface damage depth of lapped optics by fluorescent method

Abstract

Subsurface defects were fluorescently tagged with nanoscale quantum dots and scanned layer by layer using confocal fluorescence microscopy to obtain images at various depths. Subsurface damage depths of fused silica optics were characterized quantitatively by changes in the fluorescence intensity of feature points. The fluorescence intensity vs scan depth revealed that the maximum fluorescence intensity decreases sharply when the scan depth exceeds a critical value. The subsurface damage depth could be determined by the actual embedded depth of the quantum dots. Taper polishing and magnetorheological finishing were performed under the same conditions to verify the effectiveness of the nondestructive fluorescence method. The results indicated that the quantum dots effectively tagged subsurface defects of fused-silica optics, and that the nondestructive detection method could effectively evaluate subsurface damage depths.

摘要

本文利用纳米级荧光量子点对光学元件亚表面缺陷进行标记, 采用共聚焦荧光显微镜对聚焦表 面进行逐层扫描, 得到被测样品不同深度处的切片图像。通过特征点荧光强度的变化, 定量表征了熔 石英光学元件的亚表面损伤深度。结果表明, 当扫描深度超过临界值时, 最大荧光强度急剧下降, 光 学元件亚表面损伤深度可以通过量子点实际嵌入深度确定。考虑到破坏性检测方法能有效验证的无损 检测方法, 角度抛光、磁流变抛光实验在相同的条件下进行。结果表明, 纳米级量子点对光学元件的 表面缺陷具有良好的标注能力。此外, 无损检测方法可以有效地评估熔石英元件的亚表面损伤深度。