To obtain a diffraction element optimized in diffraction efficiency to respective wavelengths for a CD and for a DVD in spite of one diffraction element and an optical head system of a high light utilization efficiency using the same.
A diffraction grating 1 is provided with periodic rugged parts formed on one transparent substrate 3. The diffraction element in which the projecting parts have optical multilayered films disposed in parallel to the transparent substrate surface, the recessed parts are filled with a filler 2 of an inorganic substance or a a transparent material mainly composed of the inorganic substance and the top surface of the transparent material is made flush with the top surfaces of the projecting parts and is flat is obtained. Such element is arranged in the optical path between the light source and objective lens of the optical head system.
FUJINO YOUSUKE
OSAWA MITSUO
