Polarization by gratings used at grazing incidence

Area of Science:

• Optics and Photonics
• Materials Science
• Spectroscopy

Background:

• Concave reflection gratings are essential components in grazing incidence monochromators for spectral analysis.
• Understanding polarization effects is critical for accurate measurements in the extreme ultraviolet (EUV) range.
• Gold and aluminum coatings are commonly used for reflective optics in the EUV spectrum.

Purpose of the Study:

• To measure the polarization introduced by gold-coated and aluminum-coated concave reflection gratings.
• To investigate polarization behavior across the 20 nm to 130 nm spectral range.
• To compare experimental results with theoretical predictions for grating surfaces.

Main Methods:

• Utilized a grazing incidence monochromator setup.
• Measured polarization ratios (P = R(p)/R(s)) for gold and aluminum gratings.
• Analyzed spectral range from 20 nm to 130 nm.
• Compared experimental data with optical constants simulating a thin multilayer reflection model.

Main Results:

• Polarization ratios consistently exceeded 0.8 for wavelengths below 40 nm.
• Polarization approached unity for wavelengths below 20 nm.
• Observed polarization characteristics were consistent for both new and aged/contaminated gratings.
• Experimental results matched theoretical calculations based on a thin multilayer reflection model.

Conclusions:

• Gold and aluminum gratings exhibit significant polarization in the EUV spectral range.
• The polarization behavior can be accurately modeled by considering the grating surface as a thin multilayer film.
• These findings are important for the design and application of EUV optical systems and spectrographs.