| 摘要 |
PROBLEM TO BE SOLVED: To prevent the reflection of return light at a stem. SOLUTION: Only the circumference in a position of about 100 μm from the center of an active layer 23 of the stem 21 is provided with a coating film 28 formed by dispersing black inorganic pigment having grain size of several μm, such as carbon black, graphite and iron black, at 1 to 5 wt.% into a thermosetting resin, such as alkyd resin, epoxy resin, urethane resin and fluororesin. The return light 27 of a second side beam after being reflected by a disk is absorbed by the black inorganic pigments of the coating film 28 and the reflection thereof by the stem 21 is prevented. Accordingly, the magnitude of the displacement of the tracking error signal outputted from a photodetector to a polar '-' side is prevented from being made greater than the actuality by the incidence of the return light 27 and the normal tracking error signal is obtained. |
