The Advanced Photon Source
a U.S. Department of Energy Office of Science User Facility

X-ray Beam Wavefront Sensors, Characterization and Diagnostic

The optics group develops advanced wavefront sensing and coherence measurement techniques to support APS optics development and beamline characterization and diagnostic. Examples of applications include

  • At-wavelength metrology of X-ray optics (lenses, mirrors, crystals, and windows)
  • Beamline wavefront sensing and coherence measurements
  • Real-time beamline diagnostic (wavefront monitor for optics alignment, aberration, and vibration correction) Content not in container, usually a preliminary description.
Advanced techniques on wavefront and coherence measurements

The optics group is exploring various coherence characterization and wavefront sensing techniques based on grating interferometry and speckle tracking. A state-of-the-art wavefront-sensing technique based on coded-mask technology and deep learning was recently developed [Z. Qiao, X. Shi, M. J. Wojcik, L. Rebuffi, and L. Assoufid, Appl. Phys. Lett. 119, 011105 (2021), DOI: 10.1063/5.0053553]. This fast, high-resolution method is critical for real-time wavefront characterization and monitoring.

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Instruments

"A portable interferometer is available as a standard tool for optics testing and beamline wavefront and coherence measurements. It can be operated in multi-modes, including coded-mask-based wavefront sensing, speckle tracking, and grating interferometry. Another compact interferometer is designed for testing diffraction optics such as crystals. Both interferometers are primarily used at the 1-BM beamline [SX1] but could be deployed at other APS beamlines.

 [SX1]Link to 1-BM beamline webpage

At-wavelength metrology

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We support at-wavelength metrology measurements of X-ray optics, including lenses, mirrors, crystals, and windows. A dedicated system for high-speed characterization of lenses is developed, as shown in the figure above. Thousands of lenses designed for the APS-U beamlines will be tested for quality control

Other applications

The coded-mask-based technique can also be used as a real-time wavefront sensor for optics alignment and feedback-controlled adaptive optical systems (e.g., bendable mirrors, bimorph mirrors, and a combination of multiple focusing optics).

User Support

The optics group staff provides optics characterization and beamline diagnostic (flux, beam size, beam vibration, wavefront, and coherence) support to APS and the APS upgrade project.

Work requests can be submitted by filling the Optics Group's work request form.

 

09.03.2021