Frustrated Total Internal Reflection I (EN)


The test arrangement for ‘getting the IR into the acrylic from below to get an FTIR-effect’ works.

In theory this is how it looks like:

The silicone enables the light to travel into the acrylic..

and in reallife.. :/

Place the LEDs with a foam/polystyrene-mount in a flat angle (~30°) on the acrylic and glue them with some transparent silicone (I got some for 7.30€).

(the yellow –thing- is from a non-permanent marker…)

A few minutes later you can wire the LEDs and turn them and your camera on:

Your hand gets lightened up by the LEDs, so place a ‘Hunt for Red October’-DVD-Case in front of them. (turn your head to find Sean Connery in the images Winking smile)

We get beautiful blobs – even through the 5mm 7D006 projection acrylic Smile


All this is done by 8 LEDs. Planned are 48 each side/96 total.

Though it is much darker than a ‘real’ FTIR there’s no frame, so you don’t have to worry about water on your multitouch-table.

There’s one thing left to say: In this test arrangement finger and LEDs are on the same side of the acrylic wich is not the case in the final table.

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