Systematic-error-free wavefront measurement using an X-ray single-grating interferometer

Area of Science:

• Optics
• X-ray Interferometry
• Metrology

Background:

• X-ray interferometers utilizing the Talbot effect are crucial for high-resolution imaging.
• Systematic errors, particularly from X-ray cameras, can limit measurement accuracy.
• Accurate characterization of optical components like multilayer mirrors is essential for advanced X-ray applications.

Purpose of the Study:

• To investigate and quantify systematic errors in X-ray Talbot interferometers.
• To develop a method for eliminating camera-induced systematic errors.
• To demonstrate accurate wavefront error measurements of large numerical aperture multilayer focusing mirrors.

Main Methods:

• Detailed investigation of systematic errors in an X-ray single-grating interferometer.
• Identification of errors originating from the X-ray camera.
• Development and application of a novel error elimination technique.
• Demonstration using multilayer focusing mirrors at the SPring-8 Angstrom Compact free electron Laser (SCARF).

Main Results:

• Non-negligible systematic errors induced by the X-ray camera were identified.
• A method to eliminate these systematic errors was successfully proposed and implemented.
• Systematic-error-free wavefront error measurements were achieved.
• Wavefront aberration measurements using two different cameras showed consistency within an accuracy of better than λ/12.

Conclusions:

• Systematic errors in X-ray Talbot interferometry can be effectively identified and mitigated.
• The proposed method enables highly accurate wavefront error measurements of advanced X-ray optical elements.
• This advancement is critical for the development and application of high-numerical-aperture X-ray optics.