A conventional mechanical precision measuring device is used effectively
in the measurement of the eccentricity of a high density optical disc. A
DVR optical disc 2 comprises a pattern 4 of fine depressions and
protrusions conformed to the intended format of the disc (a first
depressions and protrusions: pits and/or grooves) formed within an
information recording area 6 of the disc, as well as a pattern 8 of fine
depressions and protrusions for measuring the eccentricity (a second
depressions and protrusions), which is formed in an area other than the
information recording area 6, and is formed in accordance with a CD
format having lower recording density than that of the format defined for
the DVR optical disc 2. By using this pattern 8 of fine depressions and
protrusions for mechanical detection, conventional mechanical precision
measuring devices designed for the CD family can be used as it is, for
measuring the eccentricity (mechanical precision) of the DVR optical disc
2.