| 摘要 |
PROBLEM TO BE SOLVED: To provide a new fluorite having a low strain double refraction (strain) and a homogeneous optical property. SOLUTION: The fluorite comprises a crystal substrate having parallel planes in the direction of <100>, wherein when the (100) plane is used as the optical plane of incidence, the average of the strain double refraction values per thickness at a wavelength of 633 nm is 0.37 to 1.79 nm/cm, and the difference (: PV) of the maximum and the minimum of the strain double refraction values per thickness at a wavelength of 633 nm is 4.0 nm/cm or less; and alternatively the fluorite comprises a crystal substrate having parallel planes in the direction of <111>, wherein when the (111) plane is used as the optical plane of incidence, the average of the strain double refraction values per thickness at a wavelength of 633 nm is 0.20 to 0.40 nm/cm, and the difference (: PV) of the maximum and the minimum of the strain double refraction values per thickness at a wavelength of 633 nm is 3.2 nm/cm or less. COPYRIGHT: (C)2008,JPO&INPIT |
