| 摘要 |
PURPOSE:To reproduce faithfully a tracking error signal and a reproducing signal and to decrease the wrong read of information by providing a light receiving means having the first and the second light receiving areas at each of the center part and the peripheral edge part of a luminous flux containing an information signal from a storage medium. CONSTITUTION:Information is written onto a information storage medium 22 by a laser luminous flux L whose optical intensity is modulated, from a semiconductor laser 21. The luminous flux containing the information from this storage medium 22 is reflected by a beam splitter 23 and made incident on the light receiving means 28. The center part of the luminous flux L is light-received by the first light receiving areas 28a of the circular shape of the center part of this light receiving means 28 and the peripheral edge part of the luminous flux L is light-received by a pair of the second and the third light-receiving areas 28b, 28c of a half annular shape. These areas 28b, 28c are placed on both sides of the area 28a, and the areas 28b, 28c are placed against the area 28a, in the direction of a tracking guide 22a of the storage medium 22 which is projected by the light-received luminous flux L, or in the direction vertical to the direction of each separate information bit.
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