| 摘要 |
PURPOSE:To obtain a satisfactory tracking characteristic by making the first and second light detecting devices into the same shape and generally a circle having the diameter smaller than the radius on a photodetecting surface, and providing the center of respective light detecting devices on the central line to form the direction vertical to the track groove of an optical beam and at the right and left positions equal in distance from the center of the optical beam. CONSTITUTION:Light detecting devices 101 and 102 are arranged in an optical beam 103, and by calculating respective outputs by a subtracter 104, a tracking error signal TE can be obtained. The size of the optical beam 103 is a diameter of 4.3mm and has a glass distribution/shaped light strength distribution. The shape of respective light detecting devices 101 and 102 is the circle of a diameter 1mm and the center is arranged at the position of 1.4mm in distance from the center of the optical beam 103 to right and left directions respectively. Thus, a TE signal error is made into a half or below, and a satisfactory tracking characteristic can be obtained to the inclination of light recording media and the horizontal dislocation of an objective lens.
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