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.