Shearing interferometer for quantifying the coherence of hard x-ray beams.

Area of Science:

• Coherent X-ray Optics
• Synchrotron Radiation Science
• Wavefront Metrology

Background:

• Undulator sources produce high-brightness X-rays crucial for advanced experiments.
• Characterizing the transverse coherence of X-ray beams is essential for applications like coherent imaging and microscopy.
• Previous methods for coherence measurement often require high-resolution detectors or are limited in spatial range.

Purpose of the Study:

• To quantitatively measure the full transverse coherence function of 14.4 keV X-ray radiation from an undulator.
• To demonstrate a novel X-ray grating interferometer technique for coherence measurements.
• To assess the applicability of this technique for spatially resolved wave front characterization.

Main Methods:

• Utilized an X-ray grating interferometer comprising a phase grating beam splitter and an amplitude grating analyzer.
• Measured the degree of coherence as a function of beam separation up to 30 micrometers.
• Employed a model-free approach for spatially resolved measurement of the complex coherence function.

Main Results:

• Successfully performed quantitative measurements of the full transverse coherence function.
• Demonstrated the capability to measure coherence over a significant range of beam separations (out to 30 micrometers).
• Validated the technique's independence from high-resolution detectors and small fields of view.

Conclusions:

• The developed X-ray grating interferometer provides a versatile and robust method for measuring transverse coherence.
• This technique enables model-free, spatially resolved characterization of X-ray wave fronts.
• The method has significant potential for applications such as detecting localized defects in beamline optics.