| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide an optical head device with a high degree of design flexibility, and high light use efficiency by mounting a diffractive element capable of controlling diffraction efficiency such as making wavelength dependence of the diffraction efficiency almost constant. <P>SOLUTION: A diffractive element is provided with cyclical concave-convex parts formed on a transparent substrate 3. Convex parts of the diffractive element have optical multilayer films 1 that have different refractive indexes and are disposed in parallel on a transparent substrate surface, and at least the concave parts of the diffractive element are filled with filling materials 2 with the refractive index different from that of the transparent substrate. The diffractive element is mounted in a light path between a light source of the optical head device and an objective lens. <P>COPYRIGHT: (C)2012,JPO&INPIT |
