Ex situ metrology and data analysis for optimization of beamline performance of aspherical pre-shaped x-ray mirrors at the advanced light source

Abstract

Super high quality aspherical x-ray mirrors with a residual slope error of ∼100 nrad (root-mean-square) and a height error of ∼1-2 nm (peak-to-valley), and even lower, are now available from a number of the most advanced vendors utilizing deterministic polishing techniques. The mirror specification for the fabrication is based on the simulations of the desired performance of the mirror in the beamline optical system and is normally given with the acceptable level of deviation of the mirror figure and finish from the desired ideal shape. For example, in the case of aspherical x-ray mirrors designed for the Advanced Light Source (ALS) QERLIN beamline, the ideal shape is defined with the beamline application (conjugate) parameters and their tolerances. In this paper, we first discuss an original procedure and dedicated software developed at the ALS X-Ray Optics Laboratory (XROL) for optimization of beamline performance of pre-shaped hyperbolic and elliptical mirrors. The optimization is based on results of ex situ surface slope metrology and consists in minimization of the mirror shape error by determining the conjugate parameters of the best-fit ideal shape within the specified tolerances. We describe novel optical metrology instrumentation, measuring techniques, and analytical methods used at the XROL for acquisition of surface slope data and optimization of the optic's beamline performance. The high efficacy of the developed experimental methods and data analysis procedures is demonstrated in results of measurements with and performance optimization of hyperbolic and elliptical cylinder mirrors designed and fabricated for the ALS QERLIN beamline.

<p>Long Non-Coding RNA NRAD1 and LINC00152 are Highly Expressed and Associated with Prognosis in Patients with Hepatocellular Carcinoma</p>

“…Functional analysis shows that NRAD1 is nuclear-localized, and its regulatory genes enrich genomewide chromatin interactions. [25][26][27] LINC00152 has been shown to play a role in the progression of many cancers, Abbreviations: CI, indicates confidence; TBL, total bilirubin; ALB, albumin; ALT, alanine aminotransferase; AFP, alpha-fetoprotein.…”

A design of resonant inelastic X-ray scattering (RIXS) spectrometer for spatial- and time-resolved spectroscopy

“…The proprietary EEM method can in principle achieve the atomic layer-by-layer material removal, and, working closely with the metrology laboratory at the ALS (XROL) to produce even more challenging mirrors for ALS-U, we believe the proposed Wolter mirrors in Table 2 can be fabricated from the improved polishing technique out of such collaboration. If the mirror figures turn out to be slightly off from the designed profiles, the effect can be partly mitigated by slightly adjusting the mirror positions and changing their incidence angles (Yashchuk et al, 2019).…”

“…SM pitch angle and detector translation, to reduce the spectral broadening by incorrect VLS parameters. For imaging subassembly, translating/pitching WM1 and WM2 can be used to compensate the figure error as shown by Yashchuk et al (2019).…”

Transfer of autocollimator calibration for use with scanning gantry profilometers for accurate determination of surface slope and curvature of state-of-the-art x-ray mirrors

“…The specified residual slope error has to be less than 175 nrad rms. This is after subtraction of the best-fit elliptical shape with the values of the conjugate parameters within the specified tolerances [66].…”

“…14b and 15b at the angular period of ~ 35 µrad, is really due to the quasi-periodic error of the mirror surface with the spatial period of about 2.1 mm. Such error is rather characteristic for some deterministic polishing processes [66,69]. In order to ensure that the error is really belong to the surface, we have performed an additional run with the mirror shifted in the tangential direction by ~ 1 mm and tilted by ~ 17 µrad.…”