The application is a multi-touch input device. All the multi-touch systems I have seen require a projector + webcam combo, and that requires a lot of space. I have also seen a system that uses IR transmitters and receivers both behind the screen, though the problem with this system is that the detectable resolution is very low due to the transmitters taking up space that could be used by more receivers (this is where FTIR is handy).
What I thought would be a more practical idea (or at least for a flatter application with a higher resolution) is to have an array of sensors (my project) behind an LCD screen with a FTIR plane in front of the screen. Or possibly integrated into the light bar's acrylic pane.
The FTIR (frustrated total internal reflection) plane would provide an excellent light source that would help the sensors register touch points.
PD3122F Datasheet - PD3122FE000F is the RoHS compliant version.
The Mouse Eye project is the exact project that inspired this idea. My original idea was to use a CMOS array as it would have a higher resolution per area per cost than a PD array, but for the sake of simplicity I though a PD array would be easier for a first project. And, the ADNB-2610 is no longer sold. I'd have to get the ADNB-2620 and through Digi-Key I'd have to make a minimum order of 6,000 @ $0.12 a piece. Excellent price if I were making multiple prototypes, but I'd rather not drop $750 at this point, if possible.
Even if I were to use a CMOS/CCD array the Arduino is limited to 20 DI/Os.
Is there a way to expand the number of inputs?
And what do you think of my project?