Absolute interferometry for fast and precise radius measurement

0560444 - ÚFP 2023 RIV US eng J - Journal Article
Kredba, Jan - Psota, Pavel - Stašík, Marek - Lédl, Vít - Veselý, Lukáš - Nečásek, Jakub
Absolute interferometry for fast and precise radius measurement.
Optics Express. Roč. 29, č. 8 (2021), s. 12531-12542. ISSN 1094-4087
R&D Projects: GA MŠMT(CZ) EF16_026/0008390
Institutional support: RVO:61389021
Keywords : interferometry * radius measurement * cavity
OECD category: Optics (including laser optics and quantum optics)
Impact factor: 3.833, year: 2021
Method of publishing: Open access
https://opg.optica.org/oe/fulltext.cfm?uri=oe-29-8-12531&id=449973

A novel radius of the curvature measurement method for optical spherical surfaces using absolute interferometry is proposed. A measurement setup is designed and built around a common-path Fizeau interferometer. The cavity length (volume of air between reference and tested surfaces) can be measured by the absolute wavelength tuning interferometry. An interconnection of data from three different tunable laser diodes (central wavelengths 780, 785 and 852 nm) allows us to measure the cavity length with uncertainty from tens to hundreds of nanometres. Once the reference radius of curvature is known/measured/calibrated, the radius of surface under test can be computed applying the value of the cavity length. The radius of curvature is measured directly in confocal position of the interferometer with relative precision of about 10 ppm. Moreover, unlike standard radius measurement by interferometry, the uncertainty of the introduced method can be optimized by selecting a suitable transmission sphere. In the paper, the method is described, tested, and verified by measuring several specimens featuring different radii of curvature. The results are analysed and furthermore compared to other measurement device.
Permanent Link: https://hdl.handle.net/11104/0333372