| 摘要 |
PURPOSE:To attain a simple lens with light weight and to obtain a responsive optical lens with small size by using a thin-film micro-Fresnel lens as the lens, providing a piezoelectric element on the thin-film lens and controlling the applied voltage to adjust the focus. CONSTITUTION:Divergent light from a laser diode 1 is formed into parallel light by a collimation lens 2 being a micro-Fresnel lens MFL, becomes linearly polarized light through a polarized beam splitter 3, stopped by an objective lens 5 being the MFL and focused to a disk 9. Since a coupling lens 6 is the micro-Fresnel lens, the pot formed to a photodetector 7 differs depending on the objective lens 5 and the disk 9, it is caught as the increase/decrease in the signal of the detector. Then the distance between the objective lens 5 and the disk 9, that is the focusing and radial tracking are controlled by using the signal of the photodetector 7. |
