A one-way see-through illumination system is constructed from a light guide panel, a front-illuminable image film, and a light injector. The light injector injects light into the light guide panel at a suitable angle for total internal reflection of the injected light at the surfaces of the light guide...http://www.google.com.au/patents/US8100575?utm_source=gb-gplus-sharePatent US8100575 - One-way see-through illumination system