The optical interferometry is a non-contact dimensional measurement technique which is capable of ultra-high-precisionmeasurements. Fundamentally, it provides the optical path difference instead of the geometrical path difference. Forthickness measurements of glass panels, the physical thickness can be extracted from the optical thickness when therefractive index of the glass panel is precisely given. Otherwise, the precision of an optical interferometer cannot bemaintained owing to errors in the refractive index. To overcome this problem, several studies based on opticalinterferometry 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. Whendelivering large glass panels, a large amount of vibration is inevitable. In this paper, a transmission-type spectral-domaininterferometer for determining physical thicknesses and group refractive indices of large glass panel, which can beoperated even under vibration conditions is introduced. For an in-line inspection, large tilt angles of glass panels arecreated by swing motion when delivering these glass panels at a high-speed. Even if the proposed method determinesphysical thickness values successfully under the severe vibration condition used here, the measurement error caused bythe vibration effect should be investigated and analyzed to correct the measured thickness values. To do this, atheoretical analysis of the error was performed by mathematical modeling. Moreover, the error of the physical thicknesswas experimentally analyzed at various tilt angles of the large glass panel. The uncertainty was evaluated to be about 436nm based on the results of these investigations.
展开▼
