Question about collimating flat emitters

[irkuck]

If one has flat LED emitter of diameter x mm, how to collect and collimate light from it in a beam of y mm diameter?

For example, if one has circular LED emitter with active area of 9 mm how to collimate light from it into a beam of 9 mm. Or if the emitter has 17 mm how to collimate it into 9 mm?. Where one could buy optics for such collimators?

 

[Gunner12]

LED dies are square and are essentually flat.

What distance do you need the beam to be what ever size?

I can't help you with the equations since I haven't taken such classes yet but there are optical simulations that you can probably use to figude out what geometry and size you need.

Also what are you trying to do?

 

[SemiMan]

LEDS are not a collimated source. You can not collimate them into a beam of "y" diameter, not really at least. You can attempt to project a spot of size Y at distance Z, but you may find your lens is impossibly large.

Semiman

 

[Ryanrpm]

Wouldn't a laser be doing pretty close to what you are asking for?:shrug::thinking:

 

[RyanA]

Lasers often use optics as well, and even so the beam still diverges over a distance.

 

[irkuck]

Perhaps I should explain this problem more:

High power LEDs are flat emitters with size big enough that they can not be approximated by point sources.

Such emitters radiate light in all half-sphere directions. The question is how to collect light from emitter and form it into a low divergence beam - "collimated" beam - with
diameter not significantly bigger (or even smaller) than the diameter of flat emitter. We assume the emitter is
circular.

In the meantime I found that there is a class of non-imaging optical concentrators which can be designed to tranport light between two apertures. However the light at the output aperture will not be precisely collimated.

 

[Benson]

Perhaps I should explain this problem more:

High power LEDs are flat emitters with size big enough that they can not be approximated by point sources.

Such emitters radiate light in all half-sphere directions. The question is how to collect light from emitter and form it into a low divergence beam - "collimated" beam - with
diameter not significantly bigger (or even smaller) than the diameter of flat emitter. We assume the emitter is
circular.

You need a reflector or lens (and hence beam) that's "large" in comparison with the source. For smaller optics, the beam will have larger divergence angles. There's nothing you can really do about geometry.

 

[irkuck]

You need a reflector or lens (and hence beam) that's "large" in comparison with the source. For smaller optics, the beam will have larger divergence angles. There's nothing you can really do about geometry.

Of course is the optics is much bigger than emitter it can be considered point source and the rest is clear.

But there is nonstandard non-imaging optics approach which possibly can help with small geometry oprics.

 

[Benson]

But there is nonstandard non-imaging optics approach which possibly can help with small geometry oprics.

Not really; you specified "collimated" which means exactly "imaged at infinity", so imaging optics are the only real options.

 

[irkuck]

Not really; you specified "collimated" which means exactly "imaged at infinity", so imaging optics are the only real options.

Looks you are right on strictly theoretical ground of infinity. But it seems if small divergence is allowed there are more possibilities.