| 摘要 |
PROBLEM TO BE SOLVED: To position an optical probe at a desired position of a storage medium by detecting light quantities at difference positions being on a recording medium with a light quantity detecting means and moving the optical probe by a control means, based on light quantities detected by a light quantity detecting means. SOLUTION: A light beam b1 from a light source 1 is passed through an objective lens 2 and a trapezoidal prism 4 to be totally reflected on the surface 5a of an optical disk 5 to generate an evanescent light. The evanescent light detected by an optical probe 7a is guided to a photodetector 6 by an optical fiber 7b and the detector 6 outputs a light quantity signal (d). A CPU 22 obtains first and second light quantity signals e1, e2 by sampling the signal (d) based on signals k1, k2 synchronized with a vibration while vibration the probe 7a in an X direction. Then, the CPU performs the positioning control of the probe 7a so that the difference signal (f) between the first and second signals e1, e2 approach zero. Moreover, the CPU 22 performs the positioning control of the probe in an Y direction by performing the control in the same manner. |
