| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide an anti-reflection coating for birefringence crystal, the coating which has reflectivities for ordinary beams and extraordinary beams simultaneously reduced in a wide wavelength range even when having the number of layers reduced to three and has a high adhesive strength and adequately adaptive to high-power light. <P>SOLUTION: On the surface of a birefringent crystal, an SiO<SB>2</SB>film having a refractive index n<SB>1</SB>of 1.47 and an optical film thickness D<SB>1</SB>of ≥0.053 and ≤0.067, a Ta<SB>2</SB>O<SB>5</SB>film having a refractive index n<SB>2</SB>of 2.1 and an optical film thickness D<SB>2</SB>of ≥0.047 and ≤0.054, and n SiO<SB>2</SB>film having a refractive index n<SB>3</SB>of 1.47 and an optical film thickness D<SB>3</SB>of ≥0.153 and ≤0.169 are successively formed as a first layer (the birefringent crystal side), a second layer, and a third layer (the air side) respectively so as to constitute a three-layered structure, wherein an optical film thickness D<SB>x</SB>is given by n<SB>x</SB>×d<SB>x</SB>/λ<SB>0</SB>where x=1,2,3, n<SB>x</SB>is the refractive index of each layer, d<SB>x</SB>is the film thickness of each layer, and λ<SB>0</SB>is a set wavelength. <P>COPYRIGHT: (C)2005,JPO&NCIPI |
