Surface gradient integrated profiler for X-ray and EUV optics

Abstract

A new ultraprecise profiler has been developed to measure, for example, asymmetric and aspheric profiles. The principle of our measuring method is that the normal vector at each point on the surface is determined by making the incident light beam on the mirror surface and the reflected beam at that point of coincident. The gradient at each point is calculated from the normal vector, and the surface profile is then obtained by integrating the gradients. The measuring instrument was designed in accordance with the above principle. In the design, four ultraprecise goniometers were applied to adjust the light axis for normal vector measurement. The anglepositioning resolution and accuracy of each goniometer are, respectively, 0.018 and 0.2 mrad. Thus, in the measuring instrument, the most important factor is the accuracy of the normal vectors measured by the goniometers. Therefore, the rotating angle-positioning errors were measured and calibrated. An elliptical profile mirror for nanometer hard-X-ray focusing was measured, and compared with the measured profile using a stitching interferometer. The absolute measurement accuracy of approximately 5 nm (peak-to-valley) was achieved. Then the measurements of 1000-mm-long flat, spherical and parabolic mirrors were demonstrated. The surface profiles of the mirrors were obtained by integrating the interpolated gradient. r

Absolute Calibration of the Rotary Encoder Considering the Influence on-Machine for Development of High-Speed Nanoprofiler

“…Presently, there is a need for the development of a new high-speed nanoprofiler that makes it possible to measure the profiles of next-generation ultraprecision mirrors [1,2]. The purpose of this study is to develop a new high-speed nanoprofiler by tracing the normal vector of an aspheric mirror surface [3][4][5]. The method of measurement adopted in this study is based upon the straightness of laser light and the accuracy of a rotation goniometer.…”