PURPOSE: To improve the workability of the optical polarizing element by shallowing grating grooves and to reduce the thickness of an optical head for an optical disk device by using the optical polarizing element.
CONSTITUTION: The surface of an optically anisotropic crystal substrate having 0.1 to 0.4 absolute value of double refraction degrees is periodically provided with diffraction gratings of ≤3μm depth L of the grating grooves 2 satisfying the relations L(ng-nt)2π/λ-2πm1 <0.2π for either of an ordinary ray or extraordinary ray where ng=the refractive index of a crystal substrate, nt=the refractive index of a grating groove material, λ=the wavelength of light, m1=an integer or L(ng-nt)2π/λ-πm2 <0.2π where m2=an odd number. Both surfaces of the substrate are provided with such diffraction gratings. As a result, the inexpensive supply of the optical polarizing elements 17 which have excellent workability and are thin and light in a large quantity is possible and the optical head for the optical device is miniaturized.
HIYOSHI YASUO
TOBA TAMAKI
NAKAMURA SHIGERU
