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

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 proje...

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Bibliographic Details
Published in:arXiv.org 2018-06
Main Authors: Ruiz-Lopez, Mabel, Dacasa, Hugo, Mahieu, Benoit, Lozano, Magali, Zeitoun, Philippe, Bleiner, Davide
Format: Article
Language:English
Subjects:
Boron carbide
Harmonic generations
Measuring instruments
Multilayers
Surface defects
Tolerances
Online Access:Get full text
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Summary: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.
ISSN:2331-8422
DOI:10.48550/arxiv.1806.10664