Patent ID: 6118586
Filing Date: 2000-09-12
Classification: G02B,G11B

Abstract:
An optical head device, whereby writing of information and/or reading out of information is carried out by irradiating an optical recording medium with light from a light source, through a diffracting element, wherein the diffracting element is provided with an optically anisotropic diffraction grating having lattice-like projections and recesses formed on the surface of a transparent substrate, and said projections and recesses are filled with a liquid crystal having an optical anisotropy, and at least the projections among the projections and recesses are formed by a transparent thin film provided on the surface of the transparent substrate, and said transparent thin film is made of SiO.sub.x N.sub.y (0.ltoreq.x<2, 0.ltoreq.y<1.3).