| 摘要 |
PURPOSE:To widen a tracking range by using plural light sources each different in wavelength, by providing a sub-deflecting means for deflecting a luminous flux before it is made incident on a main deflecting means, in the same direction as a direction in which the luminous flux is deflected by turning of the main deflecting means. CONSTITUTION:An additional deflection is provided to one incident luminous flux of an optical system. That is to say, a deflection of DELTAomega only is supplied by providing a minute turning to a sub-tracking mirror 11 before luminous flux from a semiconductor laser 1' is made incident on a translucent mirror 3'. When an angle of vie omega1 is set to 2.58 deg., the deflection quantity DELTAomega goes to 0.36', and a deflection quantity of the sub-tracking mirror 11 is about 1/430 of a main tracking mirror, and it is very small. Accordingly, s for the main tracking mirror 10, the same galvanomirror as usual is used, but as for the sub-tracking mirror 11, a mirror which has utilized a piezoelectric element, etc. can be used. |
