Vivo A, Barrett R, Perrin F
ESRF, 71 Avenue des Martyrs, CS 40220, 38043 Grenoble Cedex, France.
Rev Sci Instrum. 2019 Feb;90(2):021710. doi: 10.1063/1.5063339.
Optical metrology and polishing techniques are continuously evolving to satisfy the increasingly stringent specifications required for X-ray optical components for synchrotron and free-electron laser light source beamlines. For both spherical and aspherical geometries, the most demanding applications may have target residual figure errors close to 1 nm. To achieve such specifications and maintain them in the optomechanical mount, it is critical to develop methods capable of measuring the topography of the optical surface over the clear aperture of the mirror. The European Synchrotron Radiation Facility optical metrology laboratory has developed a stitching tool initially aimed at measuring long flat mirrors up to 1 m long with a Fizeau interferometer. The system is routinely used providing 2D maps of the optical surface. The instrument capabilities have been extended to characterize moderately curved optics using a transmission flat element, and results obtained on a high quality spherical mirror with 120 m of radius of curvature are presented. As a novel approach of stitching application, the technique has been used to improve the measurement accuracy of the Fizeau interferometer when measuring short plane mirrors. Acquisition of 2D topographies on a short plane mirror by micro-stitching interferometry is also presented and discussed.
光学计量和抛光技术不断发展，以满足同步加速器和自由电子激光光源光束线的X射线光学元件所需的日益严格的规格要求。对于球面和非球面几何形状，要求最苛刻的应用可能具有接近1纳米的目标残余面形误差。为了达到这些规格并在光机械安装中保持这些规格，开发能够测量镜体通光孔径上光学表面形貌的方法至关重要。欧洲同步辐射装置光学计量实验室开发了一种拼接工具，最初旨在用斐索干涉仪测量长达1米的长平面镜。该系统经常用于提供光学表面的二维地图。该仪器的功能已扩展到使用透射平面元件来表征中等曲率的光学元件，并展示了在曲率半径为120米的高质量球面镜上获得的结果。作为拼接应用的一种新方法，该技术已被用于提高斐索干涉仪在测量短平面镜时的测量精度。还介绍并讨论了通过微拼接干涉测量法在短平面镜上获取二维形貌的情况。
