Binary Amplitude Reflection Gratings for X-ray Shearing and Hartmann Wavefront Sensors

Goldberg, Kenneth A.; Wojdyla, Antoine; Bryant, Diane

doi:10.3390/s21020536

Cited by 8 publications

(6 citation statements)

References 36 publications

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“…This enables the transmitted X-ray beam to be continuously and efficiently used for scientific investigations. Non-invasive sensors are now available [37], but they lack the required spatial or phase sensitivity to accurately characterize X-ray wavefronts. Alternatively, other diagnostic instruments have the required spatial sensitivity, but are invasive and / or take many seconds or minutes to record the wavefront.…”

Section: Indirect and Non-invasive Control Of X-ray Wavefrontmentioning

confidence: 99%

Fast shaping control of x ray beams using a closed-loop adaptive bimorph deformable mirror

Alcock¹,

Nistea²,

Badami³

et al. 2023

Preprint

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<p> </p> <p>High-speed adaptive correction of optics, based on real-time metrology feedback, has benefitted numerous scientific communities for several decades. However, it remains a major technological challenge to extend this concept into the hard X-ray regime due to the necessity for active mirrors with single-digit nanometer height errors relative to a range of aspheric forms. We have developed the first high-resolution, real-time, closed-loop “adaptive” optical system for synchrotron and X-ray free electron laser (XFEL) applications. After calibration of the wavefront using X-ray speckle scanning, the wavefront diagnostic was removed from the X-ray beam path. Non-invasive control of the size and shape of the reflected X-ray beam was then demonstrated by driving a piezoelectric deformable bimorph mirror at ~ 1 Hz. Continuous feedback was provided by a 20 kHz direct measurement of the optical surface with picometer sensitivity using an array of interferometric sensors. This enabled a non-specialist operator to reproduce a series of pre-defined X-ray wavefronts, including focused or non-Gaussian profiles, such as flat-top intensity or multiple split-peaks with controllable separation and relative amplitude. Such changes can be applied in any order and in rapid succession without the need for invasive wavefront diagnostic sensors which block the X-ray beam for scientific usage. These innovations have the potential to profoundly change how X-ray focusing elements are utilized at synchrotron radiation and XFEL sources and provide unprecedented dynamic control of photon beams to aid scientific discoveries in a wide range of disciplines.</p>

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Section: Indirect and Non-invasive Control Of X-ray Wavefrontmentioning

confidence: 99%

Fast shaping control of x ray beams using a closed-loop adaptive bimorph deformable mirror

Alcock¹,

Nistea²,

Badami³

et al. 2023

Preprint

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“…The concept has been described previously by the authors. 12,13 The binaryamplitude reflection grating is patterned onto a silicon wafer chip that is mounted on a platform that flips into and out of the beam (Fig. 1), and we call the flipper.…”

Section: Reflection Grating Conceptmentioning

confidence: 99%

“…Several authors have described similar approaches. 12,14,15 For binary amplitude gratings with incident wavelength λ, grating-to-detector-plane distance z, and converging beam radius R (from the grating to focus), we calculate an optimal grating pitch,…”

Section: Grating Pattern Designmentioning

confidence: 99%

X-ray wavefront sensor development at the Advanced Light Source

Goldberg,

Wojdyla,

Bryant

et al. 2023

Advances in Metrology for X-Ray and EUV Optics X

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At Lawrence Berkeley National Laboratory’s Advanced Light Source, we are developing x-ray wavefront sensors to support the creation and operation of beamlines with diffraction-limited quality. Our new approach to rapid, intermittent wavefront sensing operates in reflection at glancing incidence angles and is compatible with the high-power densities of modern beamlines. For soft x-ray applications especially, the wavefront sensor can operate upstream of the exit slit in a vertically dispersed beam. This single-shot technique supports lateral shearing interferometry and Hartmann wavefront sensing; it can be adapted to speckle-based techniques as well. The reflected beam is directed to an off-axis YAG crystal that produces scintillated visible light. A small mirror reflects the light to a microscope and camera, and the measured wavefront shape information can be used as feedback to adaptive x-ray mirror elements. A compact array of gratings enables measurement across a broad range of photon energies or wavefront curvatures. We describe recent demonstrations at soft x-ray and hard x-ray wavelengths measuring an adaptive x-ray mirror, and a toroidal focusing mirror.

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“…The SI continues with the second contribution [ 2 ], describing a novel way for creating a “pseudo non-invasive” wavefront technique. It is based on reflecting Hartmann masks, intermittingly inserted into the x-ray beam, providing one-dimensional information on the X-ray wavefront.…”

Section: Contributed Papersmentioning

confidence: 99%