A light emitting unit is caused to emit a laser beam having a pulse width
T1 broader than a pulse width T2 used at a time of recording, and a light
receiving unit is caused to receive the laser beam and to output a first
detection signal. A first control signal V1 is generated by comparing a
value held at a peak level of the first detection signal with a target
value of a quantity of the laser beam, and a second control signal V2 is
generated by comparing the first control detection signal with the target
value of a quantity of the laser beam.