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Proceedings Paper

Analysis of measurement error caused by swing motion for determining the physical thickness and group refractive index of a large glass panel
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Paper Abstract

The optical interferometry is a non-contact dimensional measurement technique which is capable of ultra-high-precision measurements. Fundamentally, it provides the optical path difference instead of the geometrical path difference. For thickness measurements of glass panels, the physical thickness can be extracted from the optical thickness when the refractive index of the glass panel is precisely given. Otherwise, the precision of an optical interferometer cannot be maintained owing to errors in the refractive index. To overcome this problem, several studies based on optical interferometry for simultaneously measuring the physical thickness and refractive index have been proposed and realized. For in-line inspections, the vibration problem becomes serious with increased dimensions of thin glass panels. When delivering large glass panels, a large amount of vibration is inevitable. In this paper, a transmission-type spectral-domain interferometer for determining physical thicknesses and group refractive indices of large glass panel, which can be operated even under vibration conditions is introduced. For an in-line inspection, large tilt angles of glass panels are created by swing motion when delivering these glass panels at a high-speed. Even if the proposed method determines physical thickness values successfully under the severe vibration condition used here, the measurement error caused by the vibration effect should be investigated and analyzed to correct the measured thickness values. To do this, a theoretical analysis of the error was performed by mathematical modeling. Moreover, the error of the physical thickness was experimentally analyzed at various tilt angles of the large glass panel. The uncertainty was evaluated to be about 436 nm based on the results of these investigations.

Paper Details

Date Published: 21 June 2019
PDF: 6 pages
Proc. SPIE 11056, Optical Measurement Systems for Industrial Inspection XI, 1105604 (21 June 2019); doi: 10.1117/12.2525670
Show Author Affiliations
Jonghan Jin, Korea Research Institute of Standards and Science (Korea, Republic of)
Korea Univ. of Science and Technology (Korea, Republic of)
Jaeseok Bae, Korea Univ. of Science and Technology (Korea, Republic of)
Jungjae Park, Korea Research Institute of Standards and Science (Korea, Republic of)
Korea Univ. of Science and Technology (Korea, Republic of)

Published in SPIE Proceedings Vol. 11056:
Optical Measurement Systems for Industrial Inspection XI
Peter Lehmann; Wolfgang Osten; Armando Albertazzi Gonçalves Jr., Editor(s)

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