FIELD: information technology.
SUBSTANCE: recording medium has 3 or more recording layers arranged in series in a direction from a first recording layer to a surface on which a laser beam is incident. Each of the recording layers has a first calibration area and a second calibration area located in an outer part with respect to the first calibration area. The first calibration area located on each recording layer is located in a radial position different from the radial position of the first calibration area in each of the other recording layers. The second calibration area located on each recording layer is located in a radial position matching the radial position of the second calibration area in each of the other recording layers.
EFFECT: reduced effect of the power calibration area of each of the layers on calibration of the rest of the layers.
6 cl, 38 dwg
