OPTICAL PICKUP DEVICE FOR DOUBLE-SIDED DISK RECORDING/REPRODUCING

摘要

PROBLEM TO BE SOLVED: To record and reproduce information on a both-sided disk by irradiating both the surfaces of the both-sided disk with a 1st and a 2nd laser beam through a spectral diffusion means which is a quadrangular prism. SOLUTION: The 1st laser beam is made incident on one longitudinal surface 231 of the quadrangular prism 230 at a 45 deg. incidence angle and totally reflected at a 45 deg. reflection angle. The 1st laser beam which is totally reflected is made incident on the one longitudinal surface 231 of the quadrangular prism 230 at a 45 deg. incidence angle and totally reflected at a 45 deg. reflection angle. Then the 2nd laser beam is made incident on one lengthwise surface 233 of the quadrangular prism at a 45 deg. incidence angle and totally reflected at a 45 deg. reflection angle. Then the totally reflected laser beam is made incident on the other information surface of the both-sided disk D through a 2nd objective 270.