| 摘要 |
PROBLEM TO BE SOLVED: To provide an optical head device preventing light converged to a recording layer through an objective lens from being affected by the thickness irregularities of a transparent resin layer positioned between the recording layer and the objective lens, an information recording and reproducing device using the optical head device, an information recording and reproducing method and a thickness irregularity detection method. SOLUTION: The optical disk device 1 is provided with an out-of-focus detection system 102 detecting the out-of-focus of the objective lens 19, a thickness irregularity detection system 103 detecting the irregularities of the thickness of the transparent resin layer 3a provided most closely to the objective lens of a recording medium 2, and a thickness irregularity correction mechanism 101 changing the image formation characteristics of the light made incident on the objective lens on the basis of the change of the thickness of the transparent resin layer detected by the thickness irregularity detection system. |
