SPIE Proceedings [SPIE Eighth International Symposium on Advanced Optical Manufacturing and Testing Technology (AOMATT2016) - Suzhou, China (Tuesday 26 April 2016)] 8th International Symposium on Advanced Optical Manufacturing and Testing Technologies: Subnanometer Accuracy Measurement for Synchrotron Optics and X-Ray Optics - High accuracy measurement of power spectral density in middle spatial frequency range of optical surfaces using optical profiler