| 摘要 |
PURPOSE:To minimize absorption by disposing a thin dielectric film having the refractive index higher than the refractive index of rectangular prisms, then a thin metallic film and further a thin dielectric film having the refractive index higher than the refractive index of the rectangular prisms in this order thereby constituting a thin film part. CONSTITUTION:The thin film part of an amplitude beam splitter is constituted by disposing successively a thin ZrO2 film 17 which is a thin dielectric film having the refractive index higher than the refractive index of rectangular prisms 16, 16', then a thin Ag film 18 which is a thin metallic film and further a thin metallic ZrO2 film 19 which is the thin dielectric film having the refractive index higher than the refractive index of the prisms 16, 16'. The laser light emitted from a laser light source 21 is made incident on the thin film part from one prism 16' and the P-component and S-component of incident light 22 are respectively separated to reflected light and transmitted light in the thin film part. The absorptivity in the above-mentioned film constitution can be made as small as about 5% and therefore the quantity of the light which is nearly 1/4 the incident light 22 is obtd. in a photodetecting part 20. |
