The thing is that there are two problems with the visiblilty of the empeg's display. One of them is light reflection off of the lens. It seems like what you're suggesting might help with that problem. Unfortunately, that's not the biggest problem. What is is the light that refects off of the elements of the VFD itself. What would be nice would be a material that would allow light to pass from the VFD out to our eyes, but not allow the light from the sun penetrate the lens to get to the VFD. This, supposedly, is impossible (depends on who you ask), but something like it should be possible; for instance, mirrored sunglasses do not allow (much) light to pass from the wearer's face to someone looking at him, but they do allow light to pass from outside the glasses to the wearer's eyes.