| 摘要 |
PURPOSE:To reduce the size, thickness, and price and to improve the mass- productivity by arranging 1st areas which have rugged surface type linear periodic structure having pitch smaller than the half of light wavelength and 2nd areas which differ in thickness from the 1st area and have flat surfaces alternately on a substrate. CONSTITUTION:The 1st areas 1 which have the rugged surface type linear periodic structure having the pitch smaller than the half of the light wavelength and the 2nd areas which differ in thickness from the 1st areas and have the flat surfaces are arranged alternately on the substrate 3. The close periodic structure is utilized so as to obtain birefringence without using any expensive birefringent crystal. A phase grating whose pitch is smaller than a half as large as the wavelength of light does not refract the light and shows birefringence, which is utilized to vary the diffraction efficiency by polarization. Consequently, many elements are formed of materials such as silicon and need not be assembled, so that the thin and lightweight elements are constituted. |
