| 摘要 |
PROBLEM TO BE SOLVED: To provide a beam splitter having small absorption loss of light, small dependence on incident angle and small separation difference of polarized light is formed, and to provide a composite optical element, an optical pickup device and an optical recording/reproducing device capable of dealing with high-density and high-capacity. SOLUTION: A half mirror film 2 consisting of 20 layers 2a to 2t is formed on the face 3a to form a beam splitter film. Among the 1st to 20th layers, 1st, 5th, 11th, 15th and 19th layers 2a, 2e, 2k, 2o, 2s are, for example, TiO2 films having 2.32 refractive index, the 2nd, 4th, 6th, 8th, 10th, 12th, 14th, 16th, 18th and 20th layers 2b, 2d, 2f, 2h, 2j, 2l, 2n, 2p, 2r, 2t are, for example, Al2O3 films having 1.63 refractive index, and 3rd, 7th, 9th, 13th and 17th layers 2c, 2g, 2i, 2m, 2q are, for example, SiO2 films having 1.46 refractive index. |
