Patent ID: 6845077

Claim:
An optical pick-up device for recording/reading information on an optical recording medium, comprising: a light source for emitting a light beam; an optical system having a converging function for the light beam, through which the light beam converges on a recording surface of the optical recording medium, and through which the returning light beam that is reflected by the recording surface is collected and converges to produce a convergent returning light beam; a diffraction component for diffracting the convergent returning light beam that is reflected by the recording surface to produce a diffracted returning light beam; an optical path separator for separating the diffracted returning light beam from the light beam that is emitted from the light source toward the optical path separator, including a transparent body having a surface with a reflective region and a transmitting region, the optical path separator being arranged such that the diffracted returning light beam is reflected by the reflective region without passing into the transparent body; and a photodetector unit having a detector for detecting the diffracted returning light beam, and being disposed in an optical path of the diffracted returning light beam so as to detect the diffracted returning light beam.