| 摘要 |
PURPOSE:To make it unnecessary to execute the maintenance of a light source for detecting the pitching and rolling by detecting the recording and reproduction of information, and pitching and rolling of a carriage, through a semiconductor laser useing the LED of two wavelengths as the light source of a pickup. CONSTITUTION:A modulated write P polarized light emitted from a semiconductor laser 35 becomes parallel through a collimator lens 36 and is made incident on a polarizing part 41 through an integrated prism 37. Parallel rays of this P polarized light are made incident on the dichromic mirror 46 of a moving side pickup 32, and one of optical beams of two wavelengths which are made incident on the mirror 46 is reflected by the mirror 46, made incident on an external scale 48, and the pitching and rolling of a carriage 57 are detected. On the other hand, an optical beam which transmits through the mirror is reflected by a total reflection prism 52, and irradiated onto a disk 33. Also, a return beam reflected by the disk 33 passes through a lens 54 and a lambda/4 plate 53, and a linearly polarized light is converted by 90 deg. and reflected by the polarizing part 41 of the integrated prism 37. Accordingly, the light source 35 is not influenced by the return beam and a focus tracking error is brought to a photodetection 45. |
