LED "Tube"

[UTMonkey]

Hi All,

I am looking for a part that will enclose and focus an infrared LED beam.

I have looked online and there is nothing that comes close to what I want.

The best advice so far was a web page which suggested I cut a biro in half, paint it matt black and use that.

Surely there is something commercially available...

Regards

Mark

 

[Nigel Goodwin]

You just need a black tube and a lens, use a video camera to focus the lens, as IR and visible light have different focusing points, so you can't do it with a temporary visible LED.

Why would there be something commercially available?, it's a pretty unusual request - what are you trying to do?.

 

[UTMonkey]

Thanks Nigel,

Standard newbie project...

I want to develop an IR LED and IR Receiver on the same board, the IR LED fires off signals which are reflected by some shiny material and bounced back and read by the receiver (basic beam breaking project).


I want to ensure (as best as I can) that the IR signals come from the reflector and not walls or directly from the IR emitter itself.

I was thinking a long(ish) tube would contribute to the narrowing the beam.

Cheers

 

[Nigel Goodwin]

Check out an old Cybot project of mine, using an IR receiver IC.

 

[Blueteeth]

I assume you want this 'tube' on the IR detector? Be it photodiode or phototransistor.... I suppose having one on both the emmiter and detector would be best as you could narrow the beam (well, only let light out of the end of the tube) to your reflector, and point the detector at it as well.

Probably a lot easier to just use a tube than to go into 'optics'...even though you're not 'focusing' as such, so you'll waste a fair bit of the IR LED's light output...you could boost the gain of your detector as it is only looking at the reflector.

And modulation is obviously a must.

Blueteeth