| 摘要 |
PURPOSE:To decrease the phase difference between S- and P-polarized light by using a band pass filter consisting of multi-layered dielectric films as a separating and synthesizing element for two wavelengths. CONSTITUTION:High refractive index lambda/4 layers 11 consisting of TiO2, etc. and low refractive index lambda/4 layers 12 consisting of SiO2, etc. are alternately laminated on a substrate 10 consisting of glass, etc. and low refractive index lambda/2 layers 13 consisting of SiO2, etc., are interposed therebetween to constitute this band pass filter. The transmittance of this filter is nearly 100% near, for example, 780nm and the reflectivity is nearly 100% near 830nm with both S- and P-waves, thus the filter functions to separate and synthesize the wavelengths. The phase difference in these wavelength regions are extremely small. The deterioration of the C/N ratio occurring in the phase difference of the S- and P-polarized light is, therefore, suppressed if such filter is used. |
