Glass and Frustrated Total Internal Reflection

I spent some time playing around with a piece of normal glass, but it turns out that normal glass almost totally blocks near infra-red light! You can clearly see it’s green when viewed side on. However, it is possible to get almost perfectly clear glass that is clear side on. I got a small 8mm piece and tried it.. it works fantastic!

Here’s the setup, I’ve got the leds aimed into the glass, and a bit of foam blocks light leaking underneith the glass.

Infra-red LEDs

With a bit of card covering the LEDs so all the lights going into the glass.

LEDs covered

Touching it with my fingers, it works!

Fingers lit by FTIR

Fingers lit by FTIR again

One Response to “Glass and Frustrated Total Internal Reflection”

  1. gem Says:

    cool:) that looks awesome:)

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