| 摘要 |
PURPOSE:To obtain an optical disk apparatus having a focus error detector in which the change of a reflected light quantity or an optical axis due to the state of an optical disk recording surface scarcely influences a focus error signal. CONSTITUTION:The optical disk apparatus comprises an optical system 21 for casting a laser beam at a rotating recording medium 22, a beam splitter 25 for separating the reflected light beam from the medium into first and second convergent light beams, first and second photodetectors 13, 14 disposed on the optical paths of the first and secod light beams, and a circuit for generating a focus error signal corresponding to the difference of the outputs of the photodetectors. The photodetectors are disposed on the paths in the positional relationship in which the amplitude changes of light receiving images due to the lights upon the deviation of the focuses occurs in reverse directions to form focus error signals from the outputs of second and third areas 16a-16d to obtain a tracking control signal for allowing the positions which is irradiated with the laser beam, from the output of the spit areas 16e-16h to follow up the track of the medium. |
