benbritten.com

First off, I wanted to do an FTIR surface. I wanted to start small, make an experimental surface just for testing and such. My first surface only measured 280mm x 190mm.

As far as a camera, I was being very very impatient, and since I had some old external iSight cameras laying around, i decided to use one of those. One of the more important parts of the camera setup is the visible light filter. According to many good sources gleaned from the helpful forums at nuigroup.com, one good cheap way to do a visible light filter is to find some old film negatives and use the black bits at the end of the roll where they have basically been processed with no light exposure (ie a full black frame, like taking a picture of the inside of your lens cap). The hardest part of this was finding some old film. I havent used a film camera for 10 years or more. Luckily, my lovely girlfriend is a bit less of a techno-nerd than I so she still had some old photo laying about and I managed to scavenge 3 whole 35mm frames of black goodness. I taped those to the front of the iSight and got ready to go!

Now, unfortunately, while the iSight CCD is in fact quite sensitive to IR, it does have an IR filter inside it's optics. After doing some web searches to see if anyone had any experience removing the IR filter from an iSight i did run across a few people who said that there was one in there, but it was hard to get to (and had i read further i would have also noticed the advice that removing the IR optics bit resulted in an unusably short focal length, but I didnt) NOTE: if you have an external iSight, do NOT (i repeat: DO NOT) use it for FTIR or IR in general. you will be very disappointed.
I did however persevere and (since i have two of the externals and I am too lazy to sell them on eBay) went ahead and dissected my iSight. If for some reason you MUST use your iSight as an IR sensitive camera (don't) then here is how you do it briefly: take the thing apart. It is pretty self-explanatory. Remove lots of tiny screws, pry those little tabs etc.. once you get the actual CCD (the little black cube on the little daughterboard) you need to take the screws off the bottom of that as well, and pull teh little cube apart. There is a tiny chunk of coated glass about 3mm on a side, and about 2mm thick, it has a slight red sheen, that is the IR filter, take it out. (if i havent made it clear that this will really screw up your focus, take note: this will screw up your focus (ie can only focus very very close to the camera)).. once you have removed that, you can re-assemble and you are 'good to go' (ie it will suck)

Ok, on to the lighting. Since the local Bunnings (hardware store in Melbourne, AU) only had plexiglass that is about 2 mils (and you really want something thicker than 5 for FTIR) I had to switch gears mid-prototype and go with a Diffused Illumination scheme.

Here is a very early shot of the small surface with two IR illuminators and the modified iSight with film-negative filter:

Luckily, the small surface was fairly close to the modified iSight, so it isn't too out of focus. It was at this point that I ordered a unibrain fire-i OEM Board camera. I also got the 4.3mm lens without the IR coating and a wide lense (just to see). But while i waited on that, my extracraptacular prototype was ready for me to write some software...