Light focusing tube

Hi

I need a light focusing tube, to turn a green led with viewing angle of 120 degrees down to a small spot

I was thinking about light reflective mylar, but am open to suggestions?

This is for test equipment, so anything goes ?

Regards

Klaus

Reply to
Klaus Kragelund
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120 degrees down to a small spot
?

One trick is to literally cut the dome off the LED (if it has a dome) and polish the surface flat. This makes a nice bright LED spot instead of the diffuse glow from the dome.

Or get a lens from Edmunds if you are doing a number of these...

John :-#)#

Reply to
John Robertson

How small a spot?

Cheers

Phil Hobbs

Reply to
pcdhobbs

120 degrees down to a small spot
?

Nice trick :-)

Reply to
klaus.kragelund

The emitting LED chip is 1mm2, the receiving LED has a housing of 1mm2, but a chip of about 0.1mm2. So I would be happy to have the spot of just less than 5mm2. I am ballparking here, I would like the spot to be bigger than t he receiving LED, so that I can have production equipment that does not nee d to be top notch to "cover" the receiving LED in photons

Cheers

Klaus

Reply to
klaus.kragelund

Are you trying to change the way the LED looks, or are you trying to project a spot onto some distant surface?

Focusing is usually done with a lens.

Reply to
jlarkin

20 degrees down to a small spot

Huh, we use to electroplate copper onto SS cones... very long tapers, a few degrees.. to focus FIR (say 10-100 um) onto a detector. One grad student designed a parabolic reflector.. that did better. This is not for imaging, but just gathering as many photons as possible.

What about a lens?

George H.

Reply to
George Herold

ut a chip of about 0.1mm2. So I would be happy to have the spot of just les s than 5mm2. I am ballparking here, I would like the spot to be bigger than the receiving LED, so that I can have production equipment that does not n eed to be top notch to "cover" the receiving LED in photons

Does this require nothing in between? Can you use a light pipe? They are common to illuminate front panels from LEDs on the board behind. If the pa th is straight the light pipe just becomes a plastic cylinder. They make t hem in many shapes and sizes with various attachments.

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Reply to
Rick C

Which LED, how small?

Can you use an SMD LED instead?

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Reply to
Jasen Betts

Why not use an LED with a much narrower viewing angle?

15 degrees is relatively common eg

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At that low beam divergence it might already be good enough on its own or with a small lens in front.

The other way is to surround the detector with a non-focussing flux concentrator. But 120 degrees focussed down to a dot is a bit of an ask

- small angle approximations don't hold so you are into exotic curves.

Such things can be done there are a handful of eyepieces now with AFOV of 100 degrees or more but I don't think you will like the price.

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Short length of clear Perspex rod clear epoxy onto the water clear LED.

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Regards, 
Martin Brown
Reply to
Martin Brown

A long metal tube shiny on the inside?

piglet

Reply to
piglet

I used black delrin with a 5 mm bore to produce a narrow beam for laser tag IR...

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Reply to
TTman

Project a spot

Reply to
klaus.kragelund

120 degrees down to a small spot
?

Lens could be an option, but has to be indifferent to the length from the o bject, so it is robust against production changes

Reply to
klaus.kragelund

e:

but a chip of about 0.1mm2. So I would be happy to have the spot of just l ess than 5mm2. I am ballparking here, I would like the spot to be bigger th an the receiving LED, so that I can have production equipment that does not need to be top notch to "cover" the receiving LED in photons

e common to illuminate front panels from LEDs on the board behind. If the path is straight the light pipe just becomes a plastic cylinder. They make them in many shapes and sizes with various attachments.

Light pipe is a good idea. Don't know how much light is lost in a pipe, fou nd no numbers in the datasheets I looked into

Regards

Klaus

Reply to
klaus.kragelund

I cannot use a smaller LED. This one is a 5W++ one, so has a certain size

Reply to
klaus.kragelund

Yes, could help to find an alternative LED with more focus from the get go :-)

Reply to
klaus.kragelund

120 degrees down to a small spot
?

Yes, that is what I was looking for when talking about the reflective mylar

Maybe a problem with the extreme angles (120 degrees), that just bounces ba ck and forth between the inner sides of the tube, and when it escapes the e nd of the tube it still has 120 degrees?

Reply to
klaus.kragelund

I have just seen that you are using a 5W unit. Some of them have clip on kits to add a plastic parabolic collimator that might do what you want.

Generally the ones used in "please don't hit me lamps" on police cars etc.

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Sorry about the wacky long URL. Google clip on reflector LED.

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Regards, 
Martin Brown
Reply to
Martin Brown

On a sunny day (Tue, 13 Aug 2019 05:28:48 -0700 (PDT)) it happened snipped-for-privacy@gmail.com wrote in :

I did this once, optical fiber in hole drilled in normal LED:

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VERY small spot close to the end of the fibre. Just one of those experiments, probably not of much use in this case.

Reply to
Jan Panteltje

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