Virtual recording cells are assumed within a groove on a recording layer
of an optical recording medium. Recording marks with five or more different sizes
are formed on each of the virtual recording cells by means of modulating the irradiation
time of the laser beam in five levels or more in correspondence to the information
to be recorded. The reflectance of the virtual recording cells modulates in many
levels and the reflection level of the readout laser beam during regeneration is
modulated in five levels or more.
