| 摘要 |
PURPOSE:To record, reproduce and monitor signal by using a single light source by making a light beam thick by changing a photo image in reproducing signals, by focusing light from a light source, whose light emitting surface is rectangular, through a cylindrical lens. CONSTITUTION:Since the light emitting surface of semiconductor laser 10 is rectangular, cylindrical lenses 12 and 13 are interposed and in reproducing, cylindrical lens 13 is shifted in a light-axial direction in order to change the shape of the beam nearly in a square. To record a recording signal on the disc, the optical change of a recording material is caused by the beam waist of light made thin in a shape close to a square. To regenerate the recorded signal, irradiation with light of wider diameter than the width of an information track is needed. For the purpose, cylindrical lens 13 is shifted light-axially to obtain a light image expanded only in a direction perpendicular to the information track, thereby regenerating and monitoring the signal. |
