Lateral shift mapping metrology for X-ray telescope mirrors

Hayden J. Wisniewski; Mallory M. Whalen; Ralf K. Heilmann; Mark L. Schattenburg; Brandon D. Chalifoux

doi:10.1117/12.2594275

23 August 2021 Lateral shift mapping metrology for X-ray telescope mirrors

Hayden J. Wisniewski, Mallory M. Whalen, Ralf K. Heilmann, Mark L. Schattenburg, Brandon D. Chalifoux

Proceedings Volume 11822, Optics for EUV, X-Ray, and Gamma-Ray Astronomy X; 118220X (2021) https://doi.org/10.1117/12.2594275
Event: SPIE Optical Engineering + Applications, 2021, San Diego, California, United States

Abstract

Currently, high-resolution X-ray telescope mirrors, such as for the Lynx X-Ray Observatory concept, are measured using a Fizeau interferometer with a cylindrical null corrector. Uncertainties in the null wavefront directly couple into the surface measurement uncertainty, including the axial figure and cone angle variation. We extend the absolute surface metrology method of lateral shift mapping for measuring X-ray telescope mirror segments. Lateral shift mapping involves laterally shifting the surface under test relative to the null to multiple positions. The null wavefront can be extracted from the difference between these shifted measurements, leaving only the surface under test. Accurately extracting quadratic terms of the surface under test requires measuring its tilt during shifting. We will show surface metrology results of optical flats measured by Fizeau-based lateral shift mapping with the required angle measured using an autocollimator and compare these results against a three-flat test. We will show how we plan to extend this method to conical X-ray telescope mirror metrology. The lateral shift mapping method reduces the uncertainty introduced by the cylindrical null, a critical step toward making high-resolution X-ray telescope mirrors.

Conference Presentation

Citation Download Citation

Hayden J. Wisniewski, Mallory M. Whalen, Ralf K. Heilmann, Mark L. Schattenburg, and Brandon D. Chalifoux "Lateral shift mapping metrology for X-ray telescope mirrors", Proc. SPIE 11822, Optics for EUV, X-Ray, and Gamma-Ray Astronomy X, 118220X (23 August 2021); https://doi.org/10.1117/12.2594275

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