| 摘要 |
PURPOSE:To make an optical pickup small in size and low in cost by providing more than one refracting interfaces whose refracting forces are different in the joint surface parallel direction and joint surface orthogonal direction of a semiconductor laser, and satisfying an object side focal distances (f)PL in the parallel direction > an object side focal distance (f)NL in the orthogonal direction. CONSTITUTION:A laser beam flux outgoing from a semiconductor laser 10 is made to a parallel and circular luminous flux through a coupling lens 12, passed through a polarizing beam splitter(PBS) 14 and an objective lens 16, and converged on a recording face 41 of a recording medium 40. The reflected light is allowed to move backward, reflected on the PBS14, and made incident on a PBS18. The luminous flux transmitted through the PBS18 is transmitted through a condenser lens 30, halved by a half prism 32, made incident on a photodetector 39 through a knife edge 34, and a focusing error signal is generated. The other luminous flux is made incident on a bisected PD36, and a tracking error signal is applied. On the other hand, the light reflected on the PBS18 is made incident on PD26 and 28 through a lambda/2 wavelength plate 20, condenser lens 22, and BS24. The lens 12 is constituted of two cylinder lens 121 and 122. |
