| 摘要 |
On a record surface of an optical disk whereon basic information is recorded in a first mode of using surface irregularities, such as pits and lands, a layer of an information recording medium is formed for record and reproduction of additional information in a second mode which is different from the first mode. The information recording medium may be either a magneto-optical recording medium or a write-once recording medium. When the surface irregularities are formed along a record track with a first density, the additional information is preferably recorded in the layer of the write-once recording medium by using a second density different from the first density as the second mode along an additional track which is on the record track. It is preferred to use an alloy of terbium, iron, and cobalt as the magneto-optical recording medium to a thickness of about 800 angstrom units and to use either tellurium or an alloy of tellurium, selenium, and lead as the write-once recording medium to a thickness between 200 abd 400 angstrom units. |
