OPTICAL HEAD

摘要

PURPOSE:To improve the reliability of an optical head and to reduce the size of the device by arranging a branch type optical waveguide consisting of a waveguide lens structure having at least three opening ends, a light source such as a semiconductor laser and photodetectors on the same substrate. CONSTITUTION:The branch type optical waveguide 10 is embedded in the substrate 11 and beams 13 projected from the light source 1 such as a semiconductor laser are made parallel beams by a waveguide lens 12a and focused on the surface of a travelling recording body 14 by a waveguide lens 12b. At the recording time, high laser power is irradiated and data are recorded along a track by the change of the reflection factor of the laser power. A reproduced signal can be obtained by catching the reflected light from the recording medium 14 by the waveguide lens 12b and obtaining the sum output of a photodetector 7b arranged on the branch type optical waveguide 10 and a track signal can be obtained from the differential outputs of photodetectors 7a arranged on both the sides of an opened opening end 10b of the light waveguide 10.