Optical disk apparatus and recording and reproducing method of optical recording medium

摘要

A magnetooptic recording medium having a writing layer and a readout layer on a substrate is used. Data is recorded in the writing layer of the magnetooptic recording medium at a recording density smaller than a diameter of a focal spot of a laser beam. The data recorded in the writing layer of the magnetooptic recording medium at the recording density smaller than the beam diameter is reproduced by setting a reproducing laser power to a proper value. A reproduction laser power calibrating module executes the reproducing operation for calibration of the magnetooptic recording medium, thereby deciding the optimum value of the laser power which is used upon reproduction. For example, the reproduction laser power calibrating module measures a change in reproduction signal while raising the reproducing laser power by using a predetermined minimum reproducing laser power W0 as an initial value and a value obtained by adding a predetermined value Wc to the reproducing laser power (W) when the reproduction signal doesn't change to the optimum reproducing laser power.