| 摘要 |
PROBLEM TO BE SOLVED: To obtain a method for measuring a plate thickness which determines accurately the plate thickness of a birefringent substrate. SOLUTION: The method for measuring the plate thickness of the birefringent substrate includes a step that a relation between the plate thickness t of the birefringent substrate and a wavelengthλ(t) corresponding to a node of an amplitude of a reflective interference light intensity wavelength characteristic is determined beforehand, a step that the reflective interference light intensity wave number characteristic of the substrate is acquired, a step that a compensated reflective interference light intensity wave number characteristic is determined by a method where, in relation to the data on the reflective interference light intensity wave number characteristic in a region where a wave number is larger than that at the node of this wave number characteristic, the data at a side where the wave number is the smaller are subtracted from the data at a side where the wave number is the larger out of two data adjacent to the aforesaid data on the reflective interference light intensity wave number characteristic, and a value obtained by multiplying the result of subtraction by -1 is determined, and fresh data obtained by adding a value obtained by the multiplication to the data at the side where the wave number is the smaller are substituted for the data at the side where the wave number is the larger, and a step that the compensated reflective interference light intensity wave number characteristic is subjected to FFT processing, and thereby the plate thickness of the birefringent substrate is determined. COPYRIGHT: (C)2011,JPO&INPIT
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