| 摘要 |
PROBLEM TO BE SOLVED: To provide an optical element which has small warp even when a substrate is thin. SOLUTION: An optical multilayered thin film 2 is formed by sputtering on a surface of the substrate 1 made of glass or quartz having 0.3mm to 0.5 mm thickness (a). In a state where this film formation is completed, the substrate 1 and the optical multilayered thin film 2 have a projected shape downward in a drawing because of compressive stress of the optical multilayered thin film 2. Thereafter the substrate 1 is reversed and a SiO<SB>2</SB>film 3 is formed by sputtering on a surface of the substrate 1 opposite to the surface where the optical multilayered thin film 2 is formed (b). Thereby compressive stress of the optical multilayered thin film 2 and compressive stress of the SiO<SB>2</SB>film 3 cancels each other and curvature of the substrate 1 is mitigated. COPYRIGHT: (C)2007,JPO&INPIT
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