Abstract: The present invention is an optical spectral analysis system and method which includes transmitting light through a specimen to be analyzed. The light that is passed through the specimen is filtered. The filtering of the light is obtained by utilizing a revolving filter disk which filters the light from the specimen through a predetermined range of light wavelengths at least once per revolution. The disk is rotated by a motor. A photomultiplier tube, with associated circuitry, receives the filtered light and provides a signal representative of the intensity of the received filtered light. A computer converts the signal from the photomultiplier circuit to a spectral output.