| 摘要 |
PROBLEM TO BE SOLVED: To provide a double-refraction measuring method which is hardly influenced by a noise such as a stain or the like on the surface of an object to be inspected and which can measure the double refraction of the object to be inspected. SOLUTION: This double-refraction measuring method finds the double refraction of an object 1 to be inspected on the basis of both pieces of polarization information, i.e., polarization information on the transmitted light of the object to be inspected, which is found by a change in a light intensity obtained in such a way that the object 1 to be inspected is irradiated with nearly circularly polarized light, that a luminous flux transmitted through the object to be inspected is received by a light receiving means 9 only via an analyzer 7, and that the analyzer 7 is turned and polarization information on the transmitted light of the object to be inspected, which is found on the basis of a change in a light intensity obtained in such a way that the luminous flux transmitted through the object 1 to be inspected is received by the light receiving means 9 via a phase shifter 17 and the analyzer 7, and that the analyzer 7 is turned.
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