hey everyone, i just found this awesome thread and amazing idea!
i work for a machine vision company, programing digital cameras and pc's to take and inspect images. we worked on a project about 2 years ago where we needed to use a fresnel lens to increase the linearity of the light to get a more accurate measurement. we normally do this by MOVING THE CAMERA FURTHER AWAY, this is exactly what the fresnel lens does and why we used this. this concept and idea is awesome.
i will check at work on monday, i'm pretty sure we have samples of the material we used (it wasn't glass, so i hope it won't distort the image or colours - that system was black and white and backlit). i hope it works.