Patent ID: 7894322

Claim:
An optical pickup apparatus comprising: an irradiating device for irradiating a laser beam to perform at least one of a recording operation and a reproducing operation on a recording medium; a first light focusing device which is disposed on an optical path of the laser beam between said irradiating device and the recording medium and which focuses the laser beam on the recording medium; a collimator device which is disposed on the optical path between said irradiating device and said first light focusing device and which can be displaced along the optical path of the laser beam; a splitting device which is disposed on the optical path between said collimator device and said first light focusing device, which reflects one portion of the laser beam, and which transmits therethrough another portion of the laser beam; a light receiving device for receiving the one portion of the laser beam reflected by said splitting device; and a second light focusing device for focusing, on said light receiving device, the one portion of the laser beam reflected by said splitting device, at least one of said light receiving device and said first light focusing device being disposed at a position at which rate of change in light density of the laser beam on said first light focusing device before and after displacement of said collimator device is substantially the same as rate of change in light density of the laser beam on said light receiving device before and after the displacement of said collimator device.