Yeah I am very familiar with displacement maps, no help needed there unfortunately

but what I have originally tried was colour bars which I changed to a monchrome to get the effect I wanted, I know there is alot of guys and gals though who can do incredible things with avisynth and was wondering what sorta suggestion they had, I hadn't though of overlaying in avisynth before though, that could have real potential.
What I want ideally is something simple not to warp to much though, what you said about using caustics is what I had in mind really but then I got thinking, about avisynth generating the filter. Now I'm starting to think blender could throw in something new entirely.......