The X-Cite® exacte ultra-stable fluorescence light source employs a DC-powered mercury lamp coupled with proprietary Closed-Loop Feedback technology to provide unmatched short and long-term intensity stability, for imaging protocols lasting from milliseconds to days. With the X-Cite Optical Power Measurement System, light output can also be calibrated in absolute power units (watts), ensuring truly repeatable fluorescence illumination for imaging experiments. The X-Cite exacte microscope light source has the convenience of pre-aligned, long-life lamps and easy installation combined with innovative functions in the newest generation of mercury arc fluorescence illumination systems.