Efficient high-order suppression system for a metrology beamline

Area of Science:

• Synchrotron Radiation Science
• Optical Metrology
• Beamline Instrumentation

Background:

• High-quality metrology using synchrotron radiation necessitates high spectral purity of the incident beam.
• Traditional methods employ transmission filters, which can have limitations in suppressing higher-order radiation from monochromators.

Purpose of the Study:

• To commission and evaluate a novel high-order suppression system (HiOS) at the BESSY-II synchrotron facility.
• To assess the performance of the HiOS for improving spectral purity in the EUV and XUV ranges.

Main Methods:

• Implementation of a four-reflection mirror-based high-order suppression system (HiOS) at an at-wavelength metrology station.
• Utilized parallel-aligned mirror pairs with adjustable coatings and tunable incidence angles for optimization.
• Compared measured performance data with simulations for the EUV and XUV energy ranges.

Main Results:

• The commissioned HiOS effectively suppresses higher-order radiation, enhancing spectral purity.
• Optimized mirror coatings and incidence angles achieved a favorable figure of merit (maximum suppression at maximum transmission).
• Measured performance closely matched simulation predictions for the tested energy ranges.

Conclusions:

• The mirror-based HiOS is a viable and effective solution for achieving high spectral purity in synchrotron radiation metrology.
• The system's flexibility in terms of coatings and incidence angle allows for tailored performance across different energy ranges.
• The developed HiOS is suitable for advanced metrology applications requiring high-quality photon beams.