| 摘要 |
PURPOSE:To improve reflectivity and transmittance in a use wavelength region as well by deviating the optical film thicknesses of a 2nd layer, 4th layer, (N-2)th layer and N-th layer from lambda0/4. CONSTITUTION:A substrate is one kind of flint glass and the refractive index thereof is 1.66. TiO2, ZnS, and ZrTiO4 are conceivable as a high refractive index material and SiO2 and MgF2 as a low refractive index material; the TiO2 and SiO2 are used in this embodiment. The number of film layers is 20 layers. The optical film thickness of the 2nd layer is 0.45Xlambda0/4, the 4th layer 1.08Xlambda0/4, the 18th layer 0.90Xlambda0/4, and the 20th layer 0.41Xlambda0/4 when the design wavelength is designated as lambda0. A polarizing beam splitter with which the transmittance of P polarized light in the use wavelength band hardly deteriorates is thus obtd. even if there are the dispersion of semiconductor laser wavelength, wavelength shift and dispersion in the production of multi- layered dielectric films.
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