Surface Flatness Inspection by Shack-Hartmann Wavefront Sensing

Kuipers, Ruurd (2022) Surface Flatness Inspection by Shack-Hartmann Wavefront Sensing. Bachelor's Thesis, Astronomy.

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Abstract

High resolution Fabry-Perot performance is a requirement for future mission concepts, including Origin’s far-infrared observations to resolve narrow spectral bands of water and deuterium, important for the study of water transport in protoplanetary disks. Zero-gravity sagging and thermo-elastic processes can cause deviations in the flatness of its wafers, decreasing the angular resolution of the etalon. A concept for a flatness inspection tool for wafers is suggested with the use of Shack-Hartmann wavefront sensing. This method has the advantage of robustness to wavefront vibrations and internal alignment errors. A functional broadboard is built, automated and tested with a wafer of d=40mm. The wafer is subsequently compared with an interferometer measurement for cross-calibration. The total RMS surface error of the wafer was found to be 5.31 ± 1.37μm and 6.50 ± 0.65μm for the interferometer and Shack-Hartmann inspction tool respectively, mainly due to spherical deformation on the wafer. For future study it is suggested to test the breadboard to higher spatial-frequency surface errors and inspect stitching methods for a more extensive analyses.

Item Type:	Thesis (Bachelor's Thesis)
Supervisor name:	Jellema, W.
Degree programme:	Astronomy
Thesis type:	Bachelor's Thesis
Language:	English
Date Deposited:	19 Jul 2022 10:08
Last Modified:	19 Jul 2022 10:08
URI:	https://fse.studenttheses.ub.rug.nl/id/eprint/28020

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