1 m long multilayer-coated deformable piezoelectric bimorph mirror for adjustable focusing of high-energy X-rays

Abstract

The Diamond Light Source (DLS) beamline I15-1 measures atomic pair distribution functions (PDF) using scattering of 40-80 keV X-rays. A unique focusing element was needed to condense these X-rays from an initial large cross section (11.0 mm H × 4.2 mm V) into a required spot size of FWHM ≈680 μm (H) × 20 μm (V) at a variable position between the sample and the detector. The large numerical aperture is achieved by coating a silicon substrate over 1 m long with three multilayer stripes of Bragg angle 4.2 mrad. One stripe selects X-rays of each energy 40.0, 65.4, and 76.6 keV. Sixteen piezoelectric bimorph actuators attached to the sides of the mirror substrate adjusted the reflecting surface's shape. Focal spots of vertical width < 15 µm were obtained at three positions over a 0.92 m range, with fast, easy switching from one focal position to another. Minimized root mean square slope errors were close to 0.5 µrad after subtraction of a uniform curvature. Reflectivity curves taken along each stripe showed consistent high peaks with generally small angular variation of peak positions. This is the first application of a 1 m long multilayercoated bimorph mirror at a synchrotron beamline. Data collected with its help on a slice of a lithium ion battery's cathode are presented.

Data-driven modeling and control of an X-ray bimorph adaptive mirror

“…Among the directed shape-control tests, we drove the mirror to a set of cylindrical shapes with prescribed radii of curvature from 2 km to 6 km. This emulates the case of an adaptive mirror used to vary the focal distance, as in Sutter et al (2019). In our applications, we consider these to be relatively large moves, with central surface height changes from 146.3 nm in the 6 km case to 429.0 nm in the 2 km case.…”

“…The development of X-ray adaptive optics started in the mid-1990s (Susini et al, 1996). Over the last decade, significant advances (Mimura et al, 2010;Sawhney et al, 2010) have led to the commercial availability of piezo-bimorph mirrors (Alcock et al, 2019a;Ichii et al, 2019) and their successful deployment on several beamlines (Matsuyama et al, 2016;Sutter et al, 2019). A recent review by Cocco et al (2022) summarizes alternative approaches to deformable mirrors.…”

Адаптивная И Активная Рентгеновская Оптика

“…Разработка набора оптических компонентов, которые одновременно удовлетворяли бы требованиям к высокому потоку, высокой энергии с широкой полосой пропускания, а также эффективной и переменной фокусировке, была серьезной проблемой, которую долгое время не могли решить конструкции, используемые на большинстве каналов СИ. В работе [73] Деформируемые зеркала с механическим изгибом не обладают достаточной точностью деформации. Пьезоуправляемые ДЗ не обладают долговременной стабильностью из-за дрейфа пьезоэлектрических исполнительных механизмов, они также страдают от эффекта соединений [74], который вызывает ошибки деформации в зазорах между исполнительными механизмами.…”

Fast convolution-based performance estimation method for diffraction-limited source with imperfect X-ray optics

“…The theoretical approach proposed in Section 2 provides a tool for beamline designers to quickly evaluate the impacts of imperfect mirrors when metrology data are available. Besides, the fact that the low spatial frequency plays the killer role in focus shape distortion makes adaptive optics such as bimorph mirrors (Alcock et al, 2019ab, 2013Sutter et al, 2019) or refractive corrector (Laundy et al, 2019) an ideal solution for the focus shape correction.…”