Advances in at-wavelength metrology of x-ray optics at the Advanced Photon Source

We have made significant progress in developing at-wavelength X-ray techniques and tools for optics characterization and beamline diagnostics at the Advanced Photon Source (APS). In the past few years, advanced techniques, such as the coded-mask-based method, are routinely used to characterize lenses, mirrors, crystals, and windows for APS and the APS upgrade projects at the 28-ID-B Instrumentation Development, Evaluation & Analysis (IDEA) Beamline and the 1-BM optics and detectors testing beamline. This paper reviews our recent achievements in developing at-wavelength metrology tools and activities in characterizing and developing advanced refractive optics for the APS upgrade beamlines. We summarize the quality evaluation results of hundreds of commercial lenses and highlight the measurement procedures and application of data in designing transfocators. We then discuss the characterization of APS-fabricated silicon compound refractive lenses (CRLs) for high-energy (>40 keV) focusing, and their potential application for the CHEX beamline (Coherent High- Energy X-ray Sector for In Situ Science). Silicon CRLs fabricated by Deep Reactive Ion Etching (DRIE) with different design parameters were evaluated at the IDEA beamline. At-wavelength metrology results show that silicon CRLs are promising options as high-energy focusing optics.