| 摘要 |
PURPOSE:To control the movement of lens to an optimum state and to eliminate the fluctuation of the lens at high speed access by reducing a light from a light source through an aperture into a small diametric optical flux and monitoring the position of the optical flux by a bisplit photodetector. CONSTITUTION:An aperture 11 reducing the diameter of a part of the light radiated into the lens 1 is fixed to an optical base 20 of the objective lens driver and the 2-split photodetector 10 is fitted to the lens support 2. Then part of the light from the light source 21 is formed into a small optical flux by an aperture 11 and in detecting the position of the optical flux by the photodetector 10, the signal corresponding to the position and displacement of the objective lens 1 is obtained. The signal is fed back to a drive coil to eliminate the fluctuation of lens at high speed access and the signal is differentiated and fed back into a coil as a speed signal and the movement of lens is controlled to an optimum state. |
