| 摘要 |
PURPOSE:To simplify the constitution by setting a read beam position so that the intensity of the low-frequency component of reflected light will be between the intensity of the low-frequency component of reflected light when the read beam is off the track and that when the read beam in the center of the track. CONSTITUTION:Read beam 2 from light source 1 passes through lens system 3 and is reflected by light deflector 4 composed of a half-mirror to irradiate track 7 of optical disc 6 as a recording means by way of focus control system 5. The reflected light from optical disk 6 is photodetected by photodetector 8; the high-frequency component of the reflected light is extracted as an information signal and the low- frequency component provides the uniform intensity of the reflected light. This tracking method requires only one read beam and eliminates the need for oscillation with a high frequency, simplifying the constitutions of the optical system and control system. |
