ND FILTER, ITS MANUFACTURE METHOD AND DIAPHRAGM DEVICE INCORPORATING ND FILTER

摘要

PROBLEM TO BE SOLVED: To provide an ND filter constituted so that the surface of a sheet is prevented from being wrinkled at the time of forming a vapor-deposited film on a plastic sheet being the material of the base substance of the ND filter. SOLUTION: In the ND filter 10 having the base substance consisting of the transparent plastic sheet 11 and the vapor-deposited films 12, 13 and 14 formed on the surface of the base substance, the glass transition temperature of the sheet 11 is≥120°C. By keeping the heating temperature at the time of vapor-depositing the sheet 11 lower than the glass transition temperature, the elongating/shrinking deformation of the sheet 11 is restrained to prevent the sheet from being wrinkled. COPYRIGHT: (C)2004,JPO