| 摘要 |
PROBLEM TO BE SOLVED: To perform a correct measurement which is not affected by random emissions due to information bits by measuring the characteristic of the relation between the driving current and the outgoing light quantity of a laser in the same condition as that at the time of recording or erasing data. SOLUTION: A control circuit 11 sets the leading address Addr1 of a determined area for measurement in an address detecting circuit 10 and moves a light beam to a target address Addr1 by driving an optical head 3 with a servo circuit 12. Then, when an address coincident signal is outputted and this signal is detected, a laser driving circuit 14 controls a driving current so that a laser light quantity becomes a fixed light quantity by minitoring the laser light quantity. Then, target light quantities are set to, for example, 5 steps and respective driving currents are stored in a memory. Then, the characteristic of the realation between the driving current and the outgoing light quantity of the laser is measured in the same condition as that at the time of recording and erasing of data. Thus, the correct measurement which is not affected by the random emissions due to the information bits is performed. |
