Front monitor apparatus, and optical pickup apparatus and information recording and reproducing apparatus provided with the same

Abstract

The front monitor apparatus which monitors a laser beam emitted from a semiconductor laser element provided in the optical pickup apparatus includes first and second photodiodes each having different light receiving sensitivity, for receiving the laser beam and outputting a current corresponding to a light receiving intensity, and a current-voltage conversion circuit for differentiating voltage conversion levels for converting a current to a voltage, in association with the respective light receiving elements so that a voltage to be converted when a predetermined current is supplied from a second photodiode having low light receiving sensitivity exceeds a voltage to be converted when the predetermined current is supplied from a first photodiode having high light receiving sensitivity, and outputting a voltage which is obtained by conversion of a current from the respective light receiving elements.

Dependencies are inferred from the claim text.