Abstract: An optical-information recording/reproducing apparatus of the present invention is capable of carrying out position detection of a reproduction image even if reproduction image data with incomplete alignment marks (markers) is obtained. A relative correlation value is calculated from a first correlation value retained by a first correlation-value retaining unit and a second correlation value retained by a second correlation-value retaining unit, and pass/fail of a position detection result of the marker is judged according to the relative correlation value. The pass/fail of the position detection result is judged by mutually comparing the detection positions of the markers judged as passes by the relative correlation-value judgement, the positions of the markers judged as fail by the relative correlation-value judgement or the mutual position judgement is complemented, and the position of two-dimensional data is detected based on the pass-judged markers and the complemented markers.

Abstract: In an optical disk apparatus, recording information by irradiating a laser light from a laser diode LD upon a recording surface thereof, while rotationally driving an optical disk by means of a spindle motor 207, being provided with a front monitor diode FMD for monitoring the laser light from the LD therein, a controller portion 205 detects deterioration of the laser diode, including the kink phenomenon, in particular, of loosing the linearity in the driving characteristic thereof caused due to driving under the condition of high temperature, by comparing a laser light output detected by the FMD to that, which is detected previously, within recording operation of the apparatus, and it also makes controls to lower the rotation velocity of the optical disk. This is suitable, in particular, to the optical disk apparatus of a super or ultra-thin type.