Patent ID: 8213286

Claim:
An optical pickup apparatus comprising: a laser diode configured to generate a laser beam; an objective lens; a photodetector comprising: a substrate; a photodiode fixed to the substrate, the photodiode configured to output a signal according to a light amount of reflected light when applied with the reflected light reflected from a signal recording layer of an optical disc after the laser beam is applied to the signal recording layer thereof; and a translucent resin covering the photodiode, wherein the photodiode is prepared using a method comprising applying ultraviolet light to the translucent resin for a predetermined time in order to reduce a transmittance of the translucent resin to a level at which any further change to the transmittance caused by an application of the laser beam to the translucent resin is constrained to within a predetermined range; and an astigmatic lens configured to: apply the reflected light through the astigmatic lens onto the photodiode, and focus the reflected light at a focal point that changes position as the objective lens moves in a focusing direction, wherein: a first position of the focal point of the reflected light corresponds to a first focus position of the objective lens, the objective lens focusing the laser beam outside of the signal recording layer of the optical disc; a second position of the focal point of the reflected light corresponds to a second focus position of the objective lens, the objective lens focusing the laser beam onto the signal recording layer of the optical disc; and a thickness of the translucent resin in a direction of incidence of the reflected light on the photodiode is less than a distance between the first position of the focal point of the reflected light and the second position of the focal point of the reflected light.