Hi everyone!

Today I received my IR LEDs from eBay and decided to do a quick test with only 5.
So in the bottom left corner, I’ve got my leds (1.5v, 120mA, 850nm) plugged in serial with a 39 ohms resistor. The voltage is good on each led.
The issue is, when my hand is getting close of this corner, the light is reflected on it to the camera.

I don’t have any other than the acrylic for the moment (no sylicon, no rosco.. nothing).
I’m using an XBOX webcam and turn off all lights in the room.

Here they are some pictures that will let you understand my problem.

Here is the quick test

Here is the noise coming from the place where the only leds are:

When my hand is getting closer without touching:

When I’m touching this place:

When I’m touching the middle of the screen:

Thanks a lot guys for your help! What could I do without you?

Cover up the leds so they cannot light up your hands. They should only light up the sides of the acrylic.

you have IR leakage, you need create a bigger baffle also you need to check if all your leds are lined up straight. Also i suggest using the brightness/contrast filter in touchlib… also have you removed the background by pressing ‘b’.

I think another problem could be ambient light, which is solves by using a diffuser.  Something simple like Drafting Paper, or Tissue Paper works well.

@HyPe! I tried to cover this area but to have a good result, I need to cover 30% of the surface! That’s reduce a lot my screen size and it’s a shame.
@Taha I found BrightnessContrastFilter.cpp but I’m not sure of how using it. Should I compile it or something ?
@xelapond By “ambient light”, do you mean ambient led light ? Because when I took the screenshots, I was working during the night, without any light source, excepting my computer screen. Maybe a diffuser could help to smooth those IR leakage?

Thanks a lot men

Hey Flo,
Get some duct tape and tape over the back ends of the LEDs, from what I see in the picture - you shouldn’t be able to see the back ends in the picture. Those ends need to be covered, I dont think you need to cover over the acrylic.

I uncovered it just for the picture. It’s usually covered as the left side.
That’s what’s really wird! The strong ray angles coming from the acrylic, in front of the leds.
Oh and my leds are 30° specs.

Look at this image and tell me if you think that’s the problem.

from what i see in the picture, you lights also “leak” to the bottomside. Try to encapsulate the whole back. Another thing what might help is to move the leds further away from the sides. Trial and error.

Ok thanks a lot for your fast answer! I’ll try to move back the whole stuff and let you know

Yeees! You where right.
It was because of the thin space between the acrylic and the rail. After adjusting it, that’s fine!
Thansk again guys. You roxx.