| 摘要 |
PURPOSE:To obtain a small sized and inexpensive optical information processor having an optical pickup head having a wide position deviation range by providing a photodetector to the front and the rear side of a focal point of a split reflection converging light and using an output signal of the photodetector so as to detect the position deviation of an optical information recording medium and a focus lens from an information recording face. CONSTITUTION:The reflected converging light beams from an optical information recording medium 13 are split into two; a photodetector 12 is arranged to the front location by one prescribed interval from the rear focus F2 of a condenser lens 11 in one optical flux, and a photodetector 14 is placed in the rear direction by the same distance from the rear focus F2 in the other luminous flux. In taking the output difference from the two photodetectors 12, 14, a focus deviation detection signal is obtained and the out of focus detection signal with sufficiently high sensitivity is obtained even in the optical system with small magnification. Thus, the the focal distance of the converging light beams reflected from the optical information recording medium are decreased and the miniaturization of the optical pickup head is attained. |
