[2025] Applications of computer generated holograms for measuring X-ray and EUV optics

J. H. Burge, S. Ament, J. Beverage, C. Muccianti, and C. Zhao “Applications of computer generated holograms for measuring x-ray and EUV optics”, Proc. SPIE 13620, Advances in X-Ray/EUV Sources, Optics, and Components XX, 1362002 (18 September 2025)

Abstract:

Interferometry provides sub-nm accuracy and megapixel sampling for measuring near-spherical and flat surfaces. The addition of computer-generated holograms (CGHs) enables interferometric measurements of virtually any specular surface. Some of the most challenging optics for metrology are the mirror surfaces for systems that operate at extreme ultraviolet (EUV) and x-ray wavelengths. Measurement uncertainty below 1nm rms can be required for these surfaces, and the grazing incidence geometry of x-ray mirrors leads to peculiar long and narrow shapes with varying curvature. Often these surfaces have significant departure from spherical, so they are well suited for CGH interferometry. The challenge of achieving extreme accuracy for the measurement is addressed by pushing conventional methods to the limit, and by careful measurements and correction for systematic errors. The additional challenge of the geometry for x-ray mirrors is addressed by measuring smaller portions of the long mirror and stitching the data together.

Link to publication.