Achieving diffraction-limited nanometer-scale X-ray point focus with two crossed multilayer Laue lenses: alignment...

Area of Science:

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

Background:

• Multilayer Laue lenses (MLLs) are critical for high-resolution X-ray focusing.
• Achieving nanometer-scale X-ray point foci requires precise control over optical elements.
• Aberrations can significantly degrade the performance of X-ray focusing systems.

Purpose of the Study:

• To investigate misalignment-induced aberrations in crossed MLLs.
• To understand the impact of lens orthogonality and separation distance on X-ray focus quality.
• To establish alignment tolerances for achieving diffraction-limited nanometer-scale foci.

Main Methods:

• Theoretical modeling of misalignment effects on MLLs.
• Experimental verification using X-ray diffraction and imaging techniques.
• Analysis of astigmatism and focus spot characteristics.

Main Results:

• Orthogonality errors, especially when combined with separation distance errors, induce astigmatism at specific angles.
• The degree of astigmatism is dependent on the azimuthal angle and lens separation.
• A direct relationship was found between alignment accuracy and the achievable focus size relative to the aperture.

Conclusions:

• Precise azimuthal alignment of crossed MLLs is essential for ensuring orthogonality.
• Achieving a diffraction-limited point focus necessitates stringent control over lens alignment.
• The required alignment accuracy scales with the ratio of desired focus size to the MLL aperture size.