This small project was a long time coming.  I wanted to create a box that could be easily changed into whatever optical multitouch technique I wanted.  The 5 major techniques are FTIR, Rear DI, DSI, LLP, and LED-LP.

The box was a simple 5 sided box constructed out of MDF.  It has one of my favorite projectors in it, Toshiba’s ultra short throw TDP-EW25U (discontinued).  The camera used was an m12 PS Eye Camera in our custom acrylic box, with a varifocal m12 2.6-6mm lens.  The projected image was about the size of a 22 inch screen (16:10 ratio).  Here is a break down of the specific parts used in each setup:

FTIR

• MDF Wooded Support Frame
• Aluminum L Channel
• 8mm Infrared LED Ribbon
• 60 Watt Power Driver
• 18 x 26 inch ACRYLITE FF (extruded)
• Compliant Layer Composed of 1:1 Mixture of Clear Silicon and Xylene (Rolled Onto Vinyl Using Tinkerman Method – 4 Layers)
• 18 x 26 inch Ridout White Vinyl Polish/Matte Sides

DSI

• MDF Wooded Support Frame
• Aluminum L Channel
• 8mm Infrared LED Ribbon
• 60 Watt Power Driver
• 18 x 26 inch ACRYLITE Endlighten L
• 19 x 27 inch ACRYLITE Rear Projection Grey 7D512 RP

LLP

• 19 x 27 inch ACRYLITE FF (extruded)
• 3mm Clear Acrylic (Small Support Pieces Under Lasers) + 8 Bolts and Nuts for Laser Position Adjustments
• (2) 850nm 5mW Lasers
• (2) Laser Line Generators
• Laser Power Adapter
• Laser Safety Goggles
• Ridout White Vinyl Polish/Matte Sides

Rear DI

• 19 x 27 inch ACRYLITE FF (extruded)
• 19 x 27 inch ACRYLITE Rear Projection Grey 7D512 RP
• 4 Bar 850nm Infrared LED Kit
• 25 Infrared 850nm Module Kit

LED-LP

• 19 x 27 inch ACRYLITE FF (extruded)
• 19 x 27 inch ACRYLITE Rear Projection Grey 7D512 RP
• Aluminum L Channel
• (80) 850nm LEDs OSRAM SFH4550
• Modified Computer ATX Power Supply Outputting 12 volts

Many people modifying cameras to track infrared light sources for multitouch setups use high grade plastic or glass band pass filters, but some people are on such a tight budget that they must result to using exposed photo negative film or floppy diskette film.  As these materials do an ok job at blocking visible light and letting infrared light pass through, they are often hard to acquire or difficult to get all infrared light sources to pass through with bright enough intensity to be useful.

I have fabricated some m12 sized filters out of some black acrylic that acts as a high pass filter; blocking visible light and passing infrared.  They are listed in both the m12/CS filter section and the OEM filters.

Specifications are as follows:

Thickness: 0.125 inch (3.2mm)
Diameter: m12 (will fit in OEM, m12 and CS mounts available on this store)
Transmittance Wavelength Range: 740nm+
Average Percent Transmission: 90%
Material: Scratchable Black Acrylic

Below are some pictures and the spectral transmittance chart: