| 摘要 |
PROBLEM TO BE SOLVED: To prevent the collision of an optical head with a spindle motor for driving disk when the optical head is sent to the innermost periphery part of a disk without changing the light receiving sensitivity for laser beam with a light receiving element for monitoring. SOLUTION: An optical branching film 19c is formed between a triangular prism 19a and a triangular prism 19b, and both prisms are bonded together to form a beam splitter 19. A part of a laser beam 1 incident on the triangular prism 19b is transmitted through the optical branching film 19c, and emitted from the triangular prism 19a as a laser beam 2. The remainder of the laser beam 1 is reflected by the optical branching film 19c, and further reflected by the surface 19d of the triangular prism 19b, and made a laser beam 5 which is parallel to the laser beam 1 and has a reverse direction, emitted from the triangular prism 19b, and received by a light receiving element 17 for monitoring disposed at the same side as a semiconductor laser 11 to the beamsplitter 19. |
