| 摘要 |
PURPOSE:To decrease the scale of a reproducing device and to suppress increase in cost, by irradiating two signal tracks with two beams of primary diffracted light generated through a diffraction grating, then reproducting those two signal tracks simultaneously. CONSTITUTION:Two sports B1 and B2 of beams of primary diffracted light generated by the position diffraction grating 17 are formed on the signal surface of a disk 14. In this case, the interval between the spots BA and BB of + or - primary diffraction light beams in the radius direction of the disk 14 coincide with the distance between signal tracks TA and TB and in a correct tracking state, the spots B1 and B2 scan on the centers of the signal tracks TA and TB respectively. Then, those two signal tracks are reproduced simultaneously to decrease the number of two optical reproduction systems which are used conventionally to one, and consequently the scale of the reproducing device is reduced and an increase in cost is suppressed. |
