OPTICAL HEAD DEVICE, OPTICAL DISK DEVICE INCLUDING THIS OPTICAL HEAD DEVICE, INFORMATION RECORDING/REPRODUCING DEVICE AND OPTICAL DISK

摘要

PROBLEM TO BE SOLVED: To provide an optical head and an optical disk device, in which a stable signal is reproducible. SOLUTION: This optical head device is provided with a relay lens position control part 135 for driving a relay lens 119 in accordance with an electrical signal outputted from a 2nd photodetector 125, so as to eliminate the change of light intensity of light beams 11 converged on a recoding layer by an objective lens caused by the thickness difference of a light transmission layer 1c positioned between a recording layer 1b and an objective lens 113, and a power control circuit 134 for controlling the light intensity of the light beams emitted by a laser device 112 in accordance with the amount of the electrical signal outputted from a 1st photodetector 123.