Rotating beam splitter for the extreme vacuum ultraviolet.

Area of Science:

• Materials Science
• Optics
• Photonics

Background:

• Characterizing thin film properties is crucial for optical and electronic device development.
• Photon energy-dependent measurements require stable and precise light sources.
• Existing methods for measuring transmissivity can be affected by source intensity fluctuations.

Purpose of the Study:

• To develop and demonstrate a rotating-mirror beam splitter for precise thin film transmissivity measurements.
• To achieve efficient elimination of intensity fluctuations from electron accelerator light sources.
• To enable sensitive measurements of differential transmissivity (ΔT/T).

Main Methods:

• Construction of a rotating-mirror beam splitter operating at grazing incidence.
• Utilizing the instrument to measure thin film transmissivity in the 20-280 eV photon energy range.
• Incorporating a deflecting mirror as a photocathode in an open electron multiplier for beam monitoring.

Main Results:

• Direct measurement of thin film transmissivity with minor corrections.
• Efficient suppression of intensity fluctuations from electron accelerators.
• Achieved a sensitivity of a few tenths of a percent for differential transmissivity measurements.
• Demonstrated a highly effective beam monitor against intensity fluctuations.

Conclusions:

• The developed rotating-mirror beam splitter is a robust tool for accurate thin film characterization.
• The instrument's ability to mitigate intensity fluctuations enhances measurement reliability.
• The system offers high sensitivity for detecting subtle changes in transmissivity.