US Patent 7522509 Semiconductor laser driving device and optical disc device

In an optical disc device, the recording laser light power from a semiconductor laser is adjusted to a desired power. A front monitor PD is provided near the semiconductor laser LD of an optical pickup 16, and the recording layer light power is detected. A system controller 32 stores in memory an approximating equation for a correction coefficient for the recording power based on the detection signal characteristic when the recording laser light is a multi-pulse signal, uses the approximating equation to compute the correction coefficient for the desired recording power, corrects the detected signal level from the front monitor PD, and executes feedback control of the laser power emitted from the LD.