http://starwars.mytopix.com/lightsaber/
"The original film prop hilts were constructed from old camera-flash cylinders. The 'switched-on' sword props were designed with the intention of creating an 'in-camera' glowing effect. The 'blade' was three-sided and coated with super-reflective material-- the same sort used for highway signs. A lamp was positioned to the side of the taking camera and reflected towards the subject through 45-degree angled glass so that the sword would appear to glow from the camera's point-of-view. A motor in the hilt caused the blade to spin so that a reflective surface was always presented directly to the camera. This also created the familiar 'flickering' effect. Ultimately, this process yielded unsatisfactory results and animation was employed to enhance the brightness of the sabers. It was at this point that the artistic decision was made to assign different colors to the blades."

cyan/white