Two‐dimensional speckle technique for slope error measurements of weakly focusing reflective X‐ray optics. (5th October 2022)

• Record Type: Journal Article
• Authors: Hu, Lingfei; Wang, Hongchang; Fox, Oliver; Sawhney, Kawal
• Is Part Of: Journal of synchrotron radiation. Volume 29:Part 6(2022)
• Page Start: 1385
• Page End: 1393
• Publication Date: 2022-10-05
• Subjects: speckle technique -- X‐ray optics -- at‐wavelength metrology; Synchrotron radiation -- Periodicals; Free electron lasers -- Periodicals; 539.73505
• DOI: 10.1107/S160057752200916X
• Languages: English
• ISSNs: 0909-0495

Abstract

Abstract : This work extends the application of 2D speckle scanning techniques to the slope error measurement of weakly focusing reflective X‐ray optics. Abstract : Speckle‐based at‐wavelength metrology techniques now play an important role in X‐ray wavefront measurements. However, for reflective X‐ray optics, the majority of existing speckle‐based methods fail to provide reliable 2D information about the optical surface being characterized. Compared with the 1D information typically output from speckled‐based methods, a 2D map is more informative for understanding the overall quality of the optic being tested. In this paper, we propose a method for in situ 2D absolute metrology of weakly focusing X‐ray mirrors. Importantly, the angular misalignment of the mirror can be easily corrected with the proposed 2D processing procedure. We hope the speckle pattern data processing method presented here will help to extend this technique to wider applications in the synchrotron radiation and X‐ray free‐electron laser communities.