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arXiv · 1806.10664

Non-contact XUV metrology of Ru/B4C multilayer optics by means of Hartmann wavefront analysis

Mabel Ruiz-Lopez·Hugo Dacasa·Benoit Mahieu·Magali Lozano·Philippe Zeitoun·Davide Bleiner
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Abstract

Short-wavelength imaging, spectroscopy, and lithography scale down the characteristic length-scale to nano meters. This poses tight constraints on the optics finishing tolerances, which is often difficult to characterize. Indeed, even a tiny surface defect degrades the reflectivity and spatial projection of such optics. In this study, we demonstrate experimentally that a Hartmann wavefront sensor for extreme ultraviolet (XUV) wavelengths is an effective non-contact analytical method for inspecting the surface of multilayer optics. The experiment was carried out in a tabletop laboratory using a high-order harmonic generation as an XUV source. The wavefront sensor was used to measure the wavefront errors after the reflection of the XUV beam on a spherical Ru/B4C multilayer mirror, scanning a large surface of approximately 40 mm in diameter. The results showed that the technique detects the aberrations in the nanometer range.

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Mabel Ruiz-Lopez, Hugo Dacasa, Benoit Mahieu, Magali Lozano, Philippe Zeitoun, Davide Bleiner. 2018-06-22. Non-contact XUV metrology of Ru/B4C multilayer optics by means of Hartmann wavefront analysis. https://doi.org/10.1364/ao.57.001315

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