Open AccessSimultaneous measurement method of the physical thickness and group refractive index free from a non-measurable range
Author(s) -
Jungjae Park,
Hiroki Mori,
Jonghan Jin
Publication year - 2019
Publication title -
optics express
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.394
H-Index - 271
ISSN - 1094-4087
DOI - 10.1364/oe.27.024682
Subject(s) - optics , refractive index , optical path , materials science , interferometry , optical path length , range (aeronautics) , sample (material) , observational error , physics , mathematics , composite material , thermodynamics , statistics
An optical method to resolve the non-measurable thickness problem caused by the overlap of optical path differences within a specific thickness range when measuring the physical thickness of a sample using a spectral-domain interferometer is proposed and realized. Optical path differences can be discerned by inserting a correction glass piece into the measurement path, thus increasing the measurement optical path length. To verify the proposed method, 0.2-mm-thick N-BK7 glass was used as a sample, with physical thickness and group refractive index measurements conducted according to three different correction glass elements with corresponding nominal thicknesses of 3.0 mm, 3.5 mm, and 4.0 mm. Through uncertainty evaluations according to the correction glass used, the physical thicknesses of the sample were found to be in good agreement within measurement uncertainties of less than 100 nm, results comparable to those of previous works which did not use any correction glass.