A system for conducting an optical inspection of a biological, chemical,
or biochemical sample supported by an optically transparent disc. The
disc is mounted for rotation about its central axis while a light source
and a plurality of radiation detectors are provided for scanning
optically readable portions and tracking information encoded to the disc
and scanning the sample. The source is arranged above the disc and the
detectors are arranged above and below the disc. The optical properties
of the sample can be automatically and rapidly inspected by analyzing the
output of the light detectors including the use of a ratio of first and
second detector output. A third detector output also may be used in the
analysis.