Share Email Print
cover

Proceedings Paper

Measurement of absolute optical thickness by wavelength tuning interferometer
Author(s): Kenichi Hibino; Yangjin Kim; Youichi Bitou; Mamoru Mitsuishi
Format Member Price Non-Member Price
PDF $14.40 $18.00

Paper Abstract

Absolute optical thickness is a fundamental parameter for the design of optical elements. In semiconductor industry, it is necessary to measure the absolute optical thickness of the central part of the projection lenses with a high accuracy. However, even when the geometrical thickness is perfectly known, a typical refractive index of fused-silica has an ambiguity of 6 × 10-5 that gives an uncertainty of 180 nm in the optical thickness for a 3 mm-thick plate. Moreover, the optical thickness measured by white light interferometry and wavelength tuning interferometry is an optical thickness with respect to not the ordinary refractive index but the group refractive index. We measured the ordinary optical thickness of a fused silica plate of 6-inch square and 3 mm thickness by a wavelength tuning interferometer with a tunable phase shifting technique. We assumed the typical refractive index and dispersion of the fused silica as approximate values. The absolute interference order for the optical thickness was finally estimated, which gives a measurement resolution of typically 10 nm for the optical thickness.

Paper Details

Date Published: 3 November 2011
PDF: 8 pages
Proc. SPIE 8011, 22nd Congress of the International Commission for Optics: Light for the Development of the World, 80110B (3 November 2011); doi: 10.1117/12.901637
Show Author Affiliations
Kenichi Hibino, National Institute of Advanced Industrial Science and Technology (Japan)
Yangjin Kim, Korean Institute of Machinery and Materials (Korea, Republic of)
Youichi Bitou, National Institute of Advanced Industrial Science and Technology (Japan)
Mamoru Mitsuishi, The Univ. of Tokyo (Japan)


Published in SPIE Proceedings Vol. 8011:
22nd Congress of the International Commission for Optics: Light for the Development of the World
Ramón Rodríguez-Vera; Ramón Rodríguez-Vera; Ramón Rodríguez-Vera; Rufino Díaz-Uribe; Rufino Díaz-Uribe; Rufino Díaz-Uribe, Editor(s)

© SPIE. Terms of Use
Back to Top