A laser noise elimination circuit raises the gain of a first TIA and at
the same time reflected light from an optical disc of a laser beam is
subjected to photoelectric conversion by means of a photo detector and a
second TIA to obtain an RF signal. Then, the direct current component of
the FPD signal obtained by photoelectric conversion of part of the laser
beam by means of another photo detector and the first TIA is cut out by a
high pass filter and then subtracted by a subtracter. The gain of the
first TIA is raised in a read mode of operation for reading data from the
optical disc and lowered in a write mode of operation for writing data
onto the optical disc so as to always effectively eliminate only the
laser noise from the RF signal and prevent the circuit from being
saturated in a write mode.