| 摘要 |
PURPOSE:To minimize the error of a focus detection signal and a track detection signal by providing a condensing member in such a manner that the laser light emitted from a light source to a spacing between the light source can a spectral means can be condensed onto a spectral means. CONSTITUTION:A condenser member 8 is so provided that the laser beam from the light source 1 to the spacing between the light source 1 and the spectral means, i.e. flat plate beam splitter is condensed onto the flat plate beam splitter 2. The laser beam emitted from the light source 1 is condensed onto the flat plate beam splitter 2 by the condenser member 8 and is then changed in the optical path. The laser beam subjected to the optical path change is collimated by a collimating lens 3 to collimated beams of light which are condensed by an objective lens 4 to an optical disk 5. The reflected light from the optical disk 5 transmits the objective lens 4, the collimating lens 3 and the flat plate beam splitter 2 and is then condensed by a condenser lens 6 to a signal detector 7. The errors of the focus detection signal and the track detection signal is extremely minimized even if the spectral means, such as flat plate beam splitter 2 is inclined by a change with lapse of time or temp. change, etc. |
