| 摘要 |
PURPOSE:To make simultaneous reproduction of plural information tracks and tracking error detection at the same time by providing a diffraction grating and a light detector and thereby reproducing information of the first, second and third tracks simultaneously. CONSTITUTION:A beam spot consists of a spot 23b made by 0-order diffracted light and spots 23c, 23a caused by + or - first-order diffracted light, and each of them is irradiated on adjoining information tracks 25, 24, 26. A beam spot 19 irradiated on a light disk 8 is reflected and becomes reflected light 20, and enters a detecting section 22. A tracking error signal 5 is taken out as difference signals of photodiodes 22a, 22c by using a differential amplifier 27. On the other hand, reproduced RF signals are taken out from a photodiode 22b, and by passing outputs of photodiodes 22a, 22c through high-pass filters 28, 29 respectively. The tracking error signal is obtained by raising the intensity of + or - first- order diffracted light out of reflected light, and at the same time, irradiated information track can be read. |
