| 摘要 |
PURPOSE:To obtain a thin type two-beam optical head capable of simultaneous erasing, recording and reproducing, by providing two spots by two semiconductor laser beams having a different wavelength and the special separately means of the reflecting beam. CONSTITUTION:Laser chips 11 and 12 independently radiate laser beams for recording a comparatively long wavelength and for reproducing a short wavelength respectively and are contracted through a collimator lens 13, a 1/2 wavelength plate 14, a beam splitter 15, a mirror 16 and a focus range 17 to a track on a disk 18 as a spot 21 for recording and a spot 22 for reproducing. A reflecting beam is reversely proceeded, enters a wavelength passes, passes through lenses 24 and 25, enters a focus dislocation and track dislocation detecting optical system composed of a knife edge 26 and a division type light detector 27, a short wavelength is reflected and introduced to a magnet optical signal detecting optical system composed of an analyzer 28 and a photodetector 29. |
