| 摘要 |
PURPOSE:To reduce the constitutive parts and to enable the high speed access in miniaturization and light weight by passing a beam from a semiconductor laser through a diffraction grating, converging upon a recording medium by an objective lens and forming a recording light spot and a reproducing light spot. CONSTITUTION:The beam from the semiconductor laser 102 is converged upon the recording medium 109 formed on the surface of a transparent substrate 114. A reflected beam from the medium 109 is diffracted by the diffraction grating 105, and 1st order diffraction beams 110a and 110b are incident upon photo diodes 111a and 111b. The front faces of these diodes are bonded with polarizing plates 112a and 112b respectively. Then, the beam from the laser 102 is linearly polarized by a polarizing plate 103, and the polarizing direction of its reflected beam is rotated by the direction of recorded magnetization on the medium 109. By this method, a signal recorded on the medium 109 is thus detected out. |
