Aspheric surface measurement by absolute wavelength scanning interferometry with model-based retrace error correction

0581641 - ÚFP 2024 RIV US eng J - Journal Article
Stašík, Marek - Kredba, Jan - Nečásek, Jakub - Lédl, Vít - Fuchs, U. - Psota, Pavel
Aspheric surface measurement by absolute wavelength scanning interferometry with model-based retrace error correction.
Optics Express. Roč. 31, č. 8 (2023), s. 12449-12462. ISSN 1094-4087
R&D Projects: GA MŠMT(CZ) EF16_026/0008390
Institutional support: RVO:61389021
Keywords : interferometry * wavelength scanning * laser
OECD category: Optics (including laser optics and quantum optics)
Impact factor: 3.8, year: 2022
Method of publishing: Open access
https://opg.optica.org/oe/fulltext.cfm?uri=oe-31-8-12449&id=528666

This paper presents a non-nulling absolute interferometric method for fast and full-area measurement of aspheric surfaces without the necessity of any mechanical movement. Several single frequency laser diodes with some degree of laser tunability are used to achieve an absolute interferometric measurement. The virtual interconnection of three different wavelengths makes it possible to accurately measure the geometrical path difference between the measured aspheric surface and the reference Fizeau surface independently for each pixel of the camera sensor. It is thus possible to measure even in undersampled areas of the high fringe density interferogram. After measuring the geometrical path difference, the retrace error associated with the non-nulling mode of the interferometer is compensated for using a calibrated numerical model (numerical twin) of the interferometer. A height map representing the normal deviation of the aspheric surface from its nominal shape is obtained. The principle of absolute interferometric measurement and numerical error compensation are described in this paper. The method was experimentally verified by measuring an aspheric surface with a measurement uncertainty of λ/20, and the results were in good agreement with the results of a single-point scanning interferometer.
Permanent Link: https://hdl.handle.net/11104/0349753