| 摘要 |
PROBLEM TO BE SOLVED: To easily and exactly control laser power by temp. change. SOLUTION: Test data are written in a test area by, for instance, laser power PB as an adjusting value for the previous test, and then the written test data are read out (S001-S004). Now, a regenerative signal position Xc is detected from the test data by a positional shift detecting part (S005), and is supplied as a dislocation signal to a controller. In the controller, a laser power changing quantityΔP=f(Xc-X'c) is calculated from the regenerative signal position Xc and a stored regenerative signal position X'c (S006), and laser power PN=PB+ΔP obtained in the writing test this time is set as the laser power for performing an actual writing operation.
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