Hey,

After some quite frustrating messing around I tried just placing tracing paper under my 12mm acyclic. It seems to work fine. I read there were some issues with slight differences between the place touched on the acrylic and the projection underneath but I haven’t encountered any of this. I tried the screen from each side as well i.e. calibrate it from one side and then try using it from the opposite side to see if there was any difference in the calibration, but couldnt see any.

My table is only a prototype (see pic) so I may well be missing something but this seems ideal. Before I put any projection surface on ive found its not “touch sensitive” but requires a small amount of pressure but adding the tracing paper underneath makes no difference to this. I guess with some more sophisticated systems this could be an issue though?!?

As im touching the acrylic I tend to use a bit of moisturizer on my finger but that seems to coat the surface after a short time anyway so you dont need it after a while.

Anyway just thought id mention it as seems a quick and easy way to get an up and running prototype,

Al

Yes, FTIR works without silicone. And if you’re not using silicone you put the projection surface on the bottom just like you did.

The problem with not using a compliant surface is just like you experience. You have a hard time dragging and have to use some substance that isn’t very sanitary on top. If you’re the only one ever touching the surface, maybe moisturizer is ok, but for others having to wet your fingers and having a wet type surface is really not ideal or healthy in the long run as that surface will collect all sorts of dust a particles.

Nice Results!

By the Way, i have a Question about Tracing Paper: Will I get an even Layer with Tracing Paper if its only on the Top and not fixed between two Pices of Acrylic? I think this will become ripply and there is no chance to “stretch” it. Or am I wrong?

I also tested the Roll on Method from Tinkerman and the Paper became ripply as well.

Thanks for answers.

@JanGermany: I’m having the very same problem here. Can’t find a way to get my diffuser (with textured silicone) even. Any ideas?