| 摘要 |
PURPOSE:To realize high density recording by reading the data before rewriting and then setting a light irradiation power and a recording pulse width depending on the relationship between the condition before rewriting and data to be rewritten. CONSTITUTION:On the basis of the relationship between data B before rewriting and data C to be rewritten for each pit cell, a drive current is selcted from two kinds of currents and a high output semiconductor laser 15 near the wavelength of 800nm is modulated by a drive circuit 18 depending on this current setting value. In this case, the reflected light from a magneto-optical disk 2 of the condensed beam of a low output semiconductor laser 16 near the wavelength of 680nm is reflected by a beam splitter 10 through a quarter (1/4) wavelength plate 11 and is then received by a photo-detector 14. A spot diameter of condensed light beam near the wavelength of 680nm becomes small as much as the wavelength. Thereby, it becomes possible to reproduce a small pit and high recording density can also be realized. |
