Patent ID: 7054246

Claim:
An optical disk device for recording data by detecting pre-pit information formed on an optical disk, comprising: irradiation means for irradiating a laser beam onto the optical disk; detection means which is divided into at least two segments in the radial direction of the optical disk for detecting return light from the optical disk; adjustment means for performing adjustment such that electrical levels of two signals supplied from said detection means match; limitation means for limiting the electrical level of each of two signals supplied from said adjustment means; calculation means for calculating a difference between two signals supplied from said limitation means; and extraction means for extracting the pre-pit information contained in a signal output from said calculation means, wherein said irradiation means irradiates a laser beam of recording power and a laser beam of reproducing power or erasing power when recording data; and the limitation level of said limitation means is smaller than the level of return light when a laser beam of recording power is irradiated and is greater than the level of return light when a laser beam of reproducing power is irradiated.