Recent upgrades on optical metrology and diffraction limited x-ray mirror fabrication at NSLS-II 

Title: Recent upgrades on optical metrology and diffraction limited x-ray mirror fabrication at NSLS-II 

Speakers: Mourad Idir, Lei Huang and Tianyi Wang 

Date: Monday October 14, 2024, 2pm

Location: Advanced Light Source, B80-234 (Berkeley Lab)

Host: Antoine Islegen-Wojdyla

Description: In synchrotron applications, x-ray mirror slope specifications are crucial, especially for applications using partially coherent x-ray beams. Currently, slope errors are typically specified below 100 nrad RMS (for periods ranging from 2 mm to the full length of mirrors up to 1000 mm long and 50 mm wide). For diffraction-limited x-ray applications, such as Free Electron Lasers and Diffraction Limited Storage Rings, height specifications become more critical to maintain the beam at the diffraction limit, often requiring precision at the 1 nm or sub-nm RMS level. Meeting these demanding specifications, whether for slope or height, poses significant challenges in synchrotron mirror metrology.

Dedicated instruments are required to accurately characterize these high-precision mirrors, which can have complex surface geometries such as flat, cylindrical, elliptical, or two-dimensional curved shapes. At the NSLS-II Optics and Metrology Laboratory, several advanced metrology tools have been developed to address these challenges. Over years of R&D, our team has refined a workflow for optical metrology and x-ray mirror fabrication using ion beam figuring.

In this process, a stitching interferometer based on a Fizeau design is employed for in-process inspection, providing feedback for the ion beam figuring instrument to fabricate high-precision optics. Once a mirror meets specifications, it undergoes additional inspections using various tools such as the stitching Shack-Hartmann, nano-accuracy surface profiler, micro-stitching white light interferometer, and atomic force microscopy to ensure accuracy.

After passing these ex-situ tests, the mirrors are installed on NSLS-II beamlines. In-situ diagnostic tools, such as the X-ray Hartmann wavefront sensor, are used for final alignment, minimizing wavefront aberrations and optimizing the performance of the x-ray beam.

Biography: Mourad Idir leads and directs the Ex Situ and In Situ Metrology and Optics Fabrication effort at the NSLS-II Facility, where he also serves as the NSLS-II Experimental Development Program Manager. Dr Idir received his PhD in 1994 from Pierre and Marie Curie University in Paris, France. From 1994 to 1997, he worked at the Commissariat à l’Énergie Atomique as a scientist, developing x-ray plasma diagnostics. After completing a two-year postdoctoral fellowship at CXRO (Berkeley, USA), he joined the Centre National de la Recherche Scientifique as a scientist. In November 2010, Dr. Idir joined the NSLS-II Project after nearly ten years at Synchrotron SOLEIL in France, where he served as the group leader of the Optics and Tests Beamline. His primary research interests include ex situ and in situ metrology, optical and x-ray metrology, related instrumentation, x-ray optics R&D, as well as active x-ray optics and x-ray wavefront analysis.

Selected publications:

[1] Multi-tool optimization for computer controlled optical surfacing, Ke, X., Wang, T., Zhang, Z., Huang, L., Wang, C., Negi, V. S., ... & Idir, M. (2022).. Optics Express, 30(10), 16957-16972.

[2] Measurement uncertainty of highly asymmetrically curved elliptical mirrors using multi-pitch slope stitching technique, Huang, L., Wang, T., Polack, F., Nicolas, J., Nakhoda, K., & Idir, M. (2022).. Frontiers in Physics, 10, 414.

[3] Generalized large optics fabrication multiplexing, Kim, D., Ke, X., Pullen, W., Wang, T., Choi, H., Negi, V. S., Huang, L., & Idir, M. (2022).. Journal of the European Optical Society-Rapid Publications, 18(1), 2.

[4] Hybrid height and slope figuring method for grazing-incidence reflective optics, Wang, T., Huang, L., Ke, X., Zhu, Y., Choi, H., Pullen, W., ... & Idir, M. (2023). Journal of Synchrotron Radiation, 30(1).

[5] Computer-controlled finishing via dynamically constraint position-velocity-time scheduler, Wang, T., Ke, X., Huang, L., Negi, V., Choi, H., Pullen, W., ... & Idir, M. (2023).. Journal of Manufacturing Processes, 87, 97-105.

[6] Multi-pitch nano-accuracy surface profiler for strongly curved X-ray mirror metrology, Huang, L., Lienhard, L., Wang, T., Polack, F., Nicolas, J., Hulbert, S., & Idir, M. (2023).. Optics and Lasers in Engineering, 162, 107428

17] Review on robot-assisted polishing: Status and future trends, Ke, X., Yu, Y., Li, K., Wang, T., Zhong, B., Wang, Z., ... & Wang, C. (2023). Robotics and Computer-Integrated Manufacturing, 80, 102482.

[8] Nanometer flat blazed x-ray gratings using ion beam figure correction, Voronov, D. L., Wang, T., Park, S., Huang, L., Gullikson, E. M., Salmassi, F., ... & Idir, M. (2023). Optics Express, 31(21), 34789-34799.

[9] lon Beam Figuring System for Synchrotron X-Ray Mirrors Achieving Sub-0.2-urad and Sub-0.5-nm Root Mean Square, Wang, T., Huang, L., Zhu, Y., Giorgio, S., Boccabella, P., Bouet, N., & Idir, M. (2023).. Nanomanufacturing and Metrology, 6(1), 20.

[10] Collimated phase measuring deflectometry, Huang, L., Wang, T., Austin, C., Lienhard, L., Hu, Y., Zuo, C., ... & Idir, M. (2024). Optics and Lasers in Engineering 

[11] E-PVT: Enhanced Position-Velocity-Time scheduler for computer-controlled optical finishing with comprehensive considerations of dynamics constraints, continuity and efficiency. Ke, X., Fan, J, Wang, T., Huang, L., Zhu, Yi., ... & Idir, M. (2024) Optics Express. https://doi.org/10.1364/OE.514654

[12] A comprehensive review of dwell time optimization methods in computer-controlled optical surfacing., Wang, T., Ke, X., Huang, L., Cui, Q, ... & Idir, M. (2024) Light: Advanced Manufacturing. 

Recording