OPTICAL HEAD DEVICE AND OPTICAL INFORMATION RECORDING/REPRODUCTION DEVICE USING THE OPTICAL HEAD DEVICE

摘要

There are provided an optical head device having a high signal/noise ratio in an RF signal with a simple circuit structure and an optical information recoding/reproduction device using the same. The optical head device includes a light source, an objective lens for collecting the light emitting from the light source onto a disc-shaped optical recording medium, and a photo-detector for receiving light reflected from the optical recording medium. The optical head device further includes a diffraction optical element for dividing the reflected light from the optical recording medium into at least two groups: a first light flux group containing entire area of the cross section of the reflected light and a second light flux group containing a part of the area in the cross section of the reflected light. The photo-detector receives the first light flux group and the second light flux group at separate light reception units for detecting a track error signal used for track servo and a radial tilt signal expressing the radial tilt of the optical recording medium.