| 摘要 |
PROBLEM TO BE SOLVED: To enable stable overwrite by overwriting test-recorded information after its reproduction and evaluation without erasing it out by the use of the same recording beam again, performing its test-recording and evaluation in the same manner and determining the intensity of a proper recording beam based on the two evaluation results. SOLUTION: Test information recorded by stepwise changing the intensity of a laser beam is reproduced, and a difference of the amplitude center of a regenerative signal of short marks and long marks in succession respectively is measured, and the laser beam intensity is determined at the time wen a value of this measured difference becomes zero. Moreover, a test-recording pattern is overwritten to be recorded without erasing this area and with the same beam intensity in the same area, and similarly, the laser beam intensity is determined. When the laser beam intensities determined twice becomes coincident with each other, this intensity is regarded as the optimum value. Then, in the case of noncoincidence, a low level laser beam is shifted to the high level side, while a high level laser beam the low level side, and these values are evaluated for a proper recording beam. |
