| 摘要 |
In an optical head, a laser beam emitted from a semiconductor laser is collimatted by a convex lens and is reflected by a polarizing surface of a prism. The reflected laser beam passing through a quarter wave plate is converged by an objective lens onto an optical disk. The laser beam reflected from an optical disk is returned to the prism through the objective lens and quarter wave plate. The returned laser beam passes through the polarizing surface and is reflected from two segment surfaces of a prism coupled to the prism. The laser beam is reflected and separated into two beams by the segment surfaces. The separated beams passing through the polarizing surface are converged by the convex lens onto a photodetecting unit located close to the semiconductor laser.
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