| 摘要 |
PURPOSE:To reduce the effect of polarization by forming three layers of a low refractive index layer, a metal layer, and a high refractive index layer on a base plate in these order from the air side and causing them to satisfy prescribed conditions. CONSTITUTION:A half mirror HM is formed on a transparent base plate G of n0 refractive index by laminating three layers of a low refractive index layer L having an index of n1 and an optical film thickness of n1d1, a metal layer Me, and a high index layer H having n3 and n3d3 in due order from the air side to the base plate G. The following relationships are satisfied: 1.35<=n1<=1.45, 2.0<= n3<=2.3, 0.15lambda0<n1d1<0.21lambda0, n3d3=0.25lambda0, where lambda0 is a designed wavelength selected within the range of 400-700nm, and the thickness of the metal layer Me is selected in accordance with a desired reflectance to transmittance ratio. |
