NON-CONTACT TYPE PARALLELISM MEASURING DEVICE

PROBLEM TO BE SOLVED: To provide a method of measurement capable of improving the inspection yield in a manufacturing line by establishing the method of measurement for measuring the parallelism of the optical surface of a double refraction board, the object of measurement, with sufficient correctness and with sufficient precision in measurement without damaging optical surfaces of the double refraction board. SOLUTION: The polarized light is made to come in to a reflection material in the vertical direction or diagonal direction, the double refraction board, the object of measurement, is disposed between the polarized light and the reflection material, and the polarized light is made to come in to the bottom of the double refraction board in the vertical direction. In the method, the parallelism of both optical surfaces of the double refraction board is measured by the angle of inclination of the reflection material to the polarized light deduced from the reflection angle of the reflection light reflected in the reflection material and the angle of refraction of the transmitted light when the light, having penetrated the double refraction board and having been reflected in the reflection material, penetrates again the double fraction board. COPYRIGHT: (C)2003,JPO