Quantitative X-ray Channel-Cut Crystal Diffraction Wavefront Metrology Using the Speckle Scanning Technique

Area of Science:

• Optics and X-ray Physics
• Materials Science and Engineering

Background:

• Accurate measurement of X-ray crystal wavefronts is crucial for high-resolution diffraction applications.
• Channel-cut crystals are essential optical components in X-ray beamlines, but their surface characteristics affect performance.
• Existing methods for measuring crystal slope errors can lack the required sensitivity or resolution.

Purpose of the Study:

• To implement and validate a speckle-based method for measuring X-ray crystal diffraction wavefronts.
• To quantify the slope errors of channel-cut crystals with varying surface properties.
• To assess the potential of this method for improving crystal fabrication and enabling new X-ray applications.

Main Methods:

• A speckle scanning technique was employed, utilizing a scattering membrane moved by a piezo motor.
• X-ray deflection caused by channel-cut crystals was inferred from the speckle pattern.
• High angular sensitivity in both tangential and sagittal directions was achieved.

Main Results:

• The speckle-based method successfully measured slope errors in channel-cut crystals.
• Measured slope errors ranged from 0.25 to 2.98 μrad, depending on the crystal's cutting and etching process.
• Wavefront deformation data was simulated for beamline integration.

Conclusions:

• The implemented speckle-based method provides a sensitive tool for X-ray crystal diffraction wavefront measurement.
• The technique offers valuable feedback for crystal manufacturers to enhance channel-cut fabrication processes.
• This method paves the way for novel high-resolution X-ray diffraction applications.