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.

 
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> Semiconductor laser unit and optical head device

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