Optical read-out head capable of improved read-out of media with

Abstract

In an optical read-out head used for a multi-value information recording medium, fluctuations in a reproduction signal-to-noise ratio can be greatly reduced to reproduce reflected light with consistent performance. In an optical read-out head, after light emitted from a light source has been focussed by an objective lens, the focussed light is reflected by a multi-value information optical recording medium having a plurality of pit heights, and the reflected light passes through the objective lens, and thereafter, the reflection light is detected by a photodetector. An optical light separating element for separating the incident reflected light into diffracted sub-beams each conveying the information of a different pit height is provided in an optical path of the reflected light defined from the objective lens to the photodetector. A light receiving structure including the photodetector is provided which separately receives the diffracted beams separated by the optical light separating element.