Ruiz-Lopez Mabel, Dacasa Hugo, Mahieu Benoit, Lozano Magali, Li Lu, Zeitoun Philippe, Bleiner Davide
Appl Opt. 2018 Feb 20;57(6):1315-1320. doi: 10.1364/AO.57.001315.
Short-wavelength imaging, spectroscopy, and lithography scale down the characteristic length-scale to nanometers. This poses tight constraints on the optics finishing tolerances, which is often difficult to characterize. Indeed, even a tiny surface defect degrades the reflectivity and spatial projection of such optics. In this study, we demonstrate experimentally that a Hartmann wavefront sensor for extreme ultraviolet (XUV) wavelengths is an effective non-contact analytical method for inspecting the surface of multilayer optics. The experiment was carried out in a tabletop laboratory using a high-order harmonic generation as an XUV source. The wavefront sensor was used to measure the wavefront errors after the reflection of the XUV beam on a spherical Ru/BC multilayer mirror, scanning a large surface of approximately 40 mm in diameter. The results showed that the technique detects the aberrations in the nanometer range.
短波成像、光谱学和光刻技术将特征长度尺度缩小到纳米级。这对光学加工公差提出了严格的限制，而这些公差往往难以表征。事实上，即使是微小的表面缺陷也会降低此类光学器件的反射率和空间投影。在本研究中，我们通过实验证明，用于极紫外（XUV）波长的哈特曼波前传感器是一种检测多层光学器件表面的有效非接触分析方法。该实验在桌面实验室中使用高次谐波产生作为XUV源进行。波前传感器用于测量XUV光束在球形Ru/BC多层镜上反射后的波前误差，扫描直径约40毫米的大表面。结果表明，该技术能够检测纳米范围内的像差。
