Patent ID: 7839746

Claim:
An optical disc apparatus, comprising: a semiconductor laser configured to irradiate an optical disc with a light; a light monitor configured to monitor an emitted light from the semiconductor laser; a computing module configured to compute a sensitivity coefficient indicative of a relation between a light power of the semiconductor laser and a monitor value in the light monitor; a first deriving module configured to derive a first monitor value when the light power of the semiconductor laser at a peak power level; a second deriving module configured to derive a second monitor value when the light power of the semiconductor laser at an erase power level; a convertor configured to convert the first and the second monitor values into first and second light power values based on the sensitivity coefficient; a first calculator configured to calculate a ratio between the first and the second light power values; a second calculator configured to calculate a correction coefficient based on a ratio between the peak power level and the erase power level and the ratio between the first and the second light power values; and a correcting module configured to correct the light power value of the semiconductor laser based on the correction coefficient.