Enhanced resolution and accuracy of freeform metrology through Subaperture Stitching Interferometry

Supranowitz, Christopher M.; Maloney, Chris; Murphy, Paul E.; Dumas, Paul

doi:10.1117/12.2279821

Cited by 4 publications

(2 citation statements)

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“…The single measurements are deliberately taken with overlapping areas to conduct the fine registration, which in optical surface metrology is known as sub-aperture stitching. 1 Most usual is the combination of an areal-topography measuring instrument, like a disc scanning confocal microscope or a coherence scanning interferometer, and a translational positioning system, [1][2][3][4][5][6] but also combinations with a rotatory positioning system, 7-9 a positioning system with more than three degrees of freedom [10][11][12][13][14] or a one-dimensional point distance sensor 15 have been shown. [16][17][18][19] Various algorithms are applied to conduct the fine registration or stitching with the correction of positioning errors in a variable number of degrees of freedom.…”

Section: Introduction and Literature Reviewmentioning

confidence: 99%

Investigations on the accuracy and evaluation of the uncertainty of stitching in optical surface metrology

Schaude

Hausotte

2023

Optical Measurement Systems for Industrial Inspection XIII

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Exemplified by a stitching procedure that is frequently applied in optical surface metrology and that is based on the maximization of the cross-correlation function, the article shows the dependency of the accuracy of a stitching result on many different interdependent influence factors. Furthermore it is shown that the remaining deviations of the regions that are regarded to be the overlapping ones is no generally valid indication for the accuracy of a stitching result. Thus, in the second part of the article, a method to determine the uncertainty of a stitching result based on a Monte Carlo simulation is presented. The input quantities of the stitching procedure, namely the topographic data of the sub-apertures and the position and orientation data of the positioning system are characterized by a probability density function. Afterwards, it is sampled randomly from these probability density functions and the stitching procedure is applied many times. From the obtained distributions, the result of the stitching procedure along with its uncertainty is derived. The obtained results show metrological compatibility to the true values and furthermore enable the recognition of the cases for which the stitching did not improve but impair the accuracy compared to the accuracy of the positioning system.

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Section: Introduction and Literature Reviewmentioning

confidence: 99%

Investigations on the accuracy and evaluation of the uncertainty of stitching in optical surface metrology

Schaude

Hausotte

2023

Optical Measurement Systems for Industrial Inspection XIII

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“…Another stitching interferometry method with a spherical reference wavefront is presented in Ref. 6 measuring a specimen with 100 mm in diameter and up to 1300 μm of freeform departure from the best-fit sphere. Reference 7 presents an approach with a combination of subaperture stitching and white-light interferometry.…”

Section: Introductionmentioning

confidence: 99%

Traceable stitching interferometry for form measurement of moderately curved freeform surfaces

et al. 2022

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We present an interferometric form measurement system that is capable of measuring the form of optical surfaces from flats to moderately curved freeforms. A Fizeau interferometer is scanned over the specimen measuring its topography and the distance to the surface in subaperture measurements. The angle between the interferometer and the specimen is adjusted for each position and additionally relevant stage angle errors are measured with two tiltmeters. An optical surface with a spherical form (50 mm diameter, 10 m radius of curvature) is measured, and an uncertainty budget yields an uncertainty of 69 nm ðk ¼ 2Þ for its topography. The determined radius of curvature agrees well with the nominal specifications and a measurement with a coordinate measurement machine. Furthermore, a form measurement of a car's side window is presented. © The Authors. Published by SPIE under a Creative Commons Attribution 4.0 International License. Distribution or reproduction of this work in whole or in part requires full attribution of the original publication, including its DOI.

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Magnetorheological finishing of freeform optics using a spiral toolpath

Supranowitz

Jones

2021

Optifab 2021

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Enhanced resolution and accuracy of freeform metrology through Subaperture Stitching Interferometry

Cited by 4 publications

References 0 publications

Investigations on the accuracy and evaluation of the uncertainty of stitching in optical surface metrology

Investigations on the accuracy and evaluation of the uncertainty of stitching in optical surface metrology

Traceable stitching interferometry for form measurement of moderately curved freeform surfaces

Magnetorheological finishing of freeform optics using a spiral toolpath

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