Abstract: A method of operating a fluorescent imaging system during an open surgery procedure includes concurrently illuminating a tissue with NIR excitation light and visible light, wherein NIR fluorescent light is emitted from the tissue and collecting the NIR fluorescent light and reflected visible light that is reflected from the tissue. The method also includes blocking at least a portion of the NIR excitation light reflected from the tissue and attenuating the reflected visible light. The method further includes imaging, using a camera, the NIR fluorescent light and the attenuated reflected visible light.