Defocused travelling fringes in a scanning triple-Laue X-ray interferometry setup

Area of Science:

• Metrology
• Crystallography
• X-ray physics

Background:

• Realizing the kilogram requires precise measurement of the silicon lattice parameter.
• High-accuracy X-ray interferometry is essential for atom counting and mass redefinition.
• Systematic errors must be quantified for reliable nanometer-scale measurements.

Purpose of the Study:

• To investigate the impact of defocus on X-ray interferometer performance.
• To develop a reliable model for X-ray interferometer operation.
• To improve the accuracy of silicon lattice parameter measurements.

Main Methods:

• Analytical modeling of X-ray interferometer optics.
• Experimental investigation of defocus effects.
• Analysis of interference fringe phase shifts.

Main Results:

• Defocus significantly affects interference fringe phase.
• A quantitative relationship between defocus and lattice parameter measurement error was established.
• The study provides a method to minimize systematic errors in interferometry.

Conclusions:

• Understanding and controlling defocus is critical for high-precision lattice parameter metrology.
• The developed model enhances the reliability of X-ray interferometry for fundamental constant measurements.
• This work contributes to the accuracy required for the new kilogram definition.