| 摘要 |
PROBLEM TO BE SOLVED: To provide a film configuration and a manufacturing method capable of maintaining an antireflection effect and transmittance flatness with high accuracy even when the optical characteristics of absorptive material change in production of an ND filter having reduced reflection of front and rear surfaces. SOLUTION: Light absorption films controlling transmittance are divided and laminated and the absorption films provided on the extreme substrate side are respectively used as reflected light attenuation films to directly attenuate the reflected light from the boundary area of each layer to thereby alleviate sensitiveness to optical constants and film thicknesses. As a result, the permissible values of the film thickness control and the optical constant control are alleviated and the stable production with high quality is made possible. COPYRIGHT: (C)2007,JPO&INPIT
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