| 摘要 |
PROBLEM TO BE SOLVED: To provide a method for easily and accurately measuring a group refractive index without requiring thickness information of a sample to be measured. SOLUTION: An interferometer is constituted by serially connecting a first interferometer 2 of a Michelson type or the like and a second interferometer 3 of the same type by using a low-coherence light source as its light source. Then, an optical material to be measured 13 whose group refractive index is to be measured, and a first compensating plate 14 made of the same material are disposed on the first interferometer 2, and a second compensating plate 15 is disposed on the second interferometer. A mirror in the interferometer is scanned in the direction of its optical axis, while switching optical paths, and positions where low-coherence interference fringes appear are measured in a plurality of times, and the group refractive index is calculated based on the positions. In another method, the optical material to be measured whose group refractive index is to be measured, and one compensating plate made of the same material are employed to a triangular optical path interferometer. While the optical material to be measured is operated together with one compensating plate in the direction of its optical axis, the positions where the low-coherence interference fringes appear are measured, and the group refractive index is calculated. COPYRIGHT: (C)2007,JPO&INPIT
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