Is it possible to limit IR led so sensor detects it only if you aim at it


I will have IR led and IR sensor as in TV. As you know, even if you don't point at the TV you are able to change channels.

My question is, is it possible to limit it somehow (maybe by putting the LED into some hollow cylinder)?

Best Answer

I repair guns for a system called "Battle Sports". That employs an infra-red emitter combined with a couple of white LEDs in the gun:

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That module is placed at one end of a plastic tube, about 6 inches long. At the other end of the tube is a lens. The lens is specifically shaped, and placed, so that the light from the module is focused into a roughly parallel beam. That translates to the white light forming a spot a couple of inches across (used to aim with), and the IR light covering roughly the same area.

The IR is modulated at 56KHz, with a pulsed on/off signal to identify that it's a proper gun that's in use.

The gun also has an IR receiver module on it, as well as a pair of receivers that the user wears on a headband. These are a simple amplifier / filter arrangement that just returns the pulses without the 56KHz modulation. They are domed, with a full 360° / 180° range on them, so they can be shot from any angle.