READING DEVICE AND READING METHOD FOR AN OPTICAL DATA RECORDING MEDIUM

摘要

A reading devices suppresses deterioration of the recording marks caused by increasing the output laser power to compensate for a drop in the S/N ratio when reading at a high speed information recorded to a high density recording medium. To read information recorded to an optical data recording medium that is written and read using a laser beam output from a semiconductor laser, the reading method modulates a high frequency current on the drive current of the semiconductor laser to output the laser beam, and changes the light modulation rate according to the selected linear velocity used for reading. The light modulation rate is the ratio Pp/Pave between the peak power Pp and the average read power Pave of the light intensity of the high frequency modulated laser beam.