A centrifuge blood processing system for separating fluid components comprising a first light source comprising a plurality of light emitting diodes in optical communication with the centrifuge blood processing system for providing an incident light beam for illuminating an observation region on the centrifuge blood processing system, a light collection element in optical communication with the centrifuge blood processing system for collecting at least a portion of the light transmitted, scattered or both from the observation region, a programmable controller for providing an operational procedure for the monitoring system; and an independent dedicated control circuit in electrical communication with the programmable controller and electrically coupled to the light source, the control circuit receiving command parameters from the controller and controlling periods of illumination from the light source in response to the command parameters. Periods of illumination are controlled to prevent the failure of LEDs.