| 摘要 |
PROBLEM TO BE SOLVED: To make an optical low-pass filter thinner in a more easily manufacturable state. SOLUTION: A lithium niobate (LN: LiNbO<SB>3</SB>) crystal plate 101 and a quartz plate 102 are arranged on an optical path through which incident light passes. The LN crystal plate 101 is a parallel flat plate of, for example, 135°in cutting angle and 0.160 mm in plate thickness. The quartz plate 102 is a parallel flat plate of, for example, 45°in cutting angle and 0.36 mm in plate thickness. The LN crystal plate 101 has a double refractive index higher than that of the quartz plate 102 and the separation direction of the quartz plate 102 with respect to the lithium niobate crystal plate 101 is 180°. COPYRIGHT: (C)2004,JPO
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