| 摘要 |
PURPOSE:To make possible a driving method for optical path and focus position controlling which is of small capacity, is mechanically stable and suitable for mass production by disposing a focusing optical system, semiconductor light source and photo detector from the informaftion structural body side in this order on a straight line within the same lens-barrel. CONSTITUTION:A condensing lens group 8, semitransparent mirror 10 and photo setector 11 are disposed within a lens-barrel 12 on one straight line as shown in the figure. The light source of a read beam is placed on the outside and the beam enters the inside of the lens-barrel 12 through the beam incident window 13 provided to the lens-barrel 12. It is then reflected by the semi-transparent mirror 10 and is condensed onto the information structural body 14 by the condensing lens group 9. The read beam having been reflected and modulated by the structural body 14 again transmits through the lens group 9 and mirror 10, then enters the detector 11 where it is converted to an electric signal. The use of a semiconductor laser for the beam light source micro-miniaturizes the light source. In the miniature read optical system, the focal position of the optical system may be moved by supporting the lens-barrel 12 on a T-form leaf spring 18 and electromagnetically driving the spring 18. |
