A question of ignorance

Endeavour

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Hey Folks,

This will probably seem like a rather stupid question, but I must know...

I've read the Lumileds tech docs, and still cannot figure out the difference between a Luxeon Lambertian and Batwing LED are.

Could someone please explain this to me in plain english? /ubbthreads/images/graemlins/help.gif

Thanks. /ubbthreads/images/graemlins/bowdown.gif

-EM
 

LEDependent

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Lambertian is a high-dome (HD) emitter. It has a perfectly round lens on top, giving an even distribution through all angles. Batwings are low-dome (LD). They have a flatter top, and they project a visible circle.
 

Kiessling

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they have different shpaes of the dome; the lambertian being a so-called "high-dom (HD)" and the batwing the "low-dome (LD) ... resulting in different light distribution and different needs for optix, reflectors ...
bernhard
 

flashlightDR

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From the ARC web site:

High Dome vs Low Dome

As explained above under how a white LED works, a phospor layer is used to re-emit some of the blue light. In most white LEDs, the phosphor is applied as a cap or fill around the LED chip ("die").

Lumileds started manufacturing their luxeon stars with a phosphor cap. This is called the "low dome" design because the dome over the LED is low and flat. In 2002, Lumileds improved the Luxeon Star by coming out with the EOS process. This EOS process changed how the phosphor is applied to the die. The die now has a even coating over the entire surface. This change was included with the new invertered die geometry in their "high dome" design. The high dome product has a higher dome over the LED with a rounded tip.

Low dome LEDs, which are in the majority, have a tint gradient across the beam. Typically, the center of the beam is blueish while the edges are greenish.

High dome LEDs have a more consistant tint across the beam. They also have a smaller object size which makes for a more focused beam for a given optic. HDs (high domes) also show the die pattern and bond wires more clearly in the beam.
 

Topper

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I did not know if I had known I would have Answered quicker than they did Penn. Or Germany, Arkansas is alot closer.
/ubbthreads/images/graemlins/grin.gif /ubbthreads/images/graemlins/grin.gif /ubbthreads/images/graemlins/grin.gif
Topper /ubbthreads/images/graemlins/smile.gif
 

Endeavour

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That's the second time I have no idea what you said... /ubbthreads/images/graemlins/confused.gif

[ QUOTE ]
Topper said:
I did not know if I had known I would have Answered quicker than they did Penn. Or Germany, Arkansas is alot closer.
/ubbthreads/images/graemlins/grin.gif /ubbthreads/images/graemlins/grin.gif /ubbthreads/images/graemlins/grin.gif
Topper /ubbthreads/images/graemlins/smile.gif

[/ QUOTE ]
 

Endeavour

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So, here's the question rephrased, aside from Low Dome and High Dome - I got that part. Which of the two will produce a brighter, tighter beam if put in, say, a Fraen LP?
 

FlashlightOCD

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I believe I've read that a Fraen optic has very little effect on the Low Dome. On a high dome the Fraen will produce a tighter [smaller] and brighter beam with very little side spill.
 

idleprocess

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I've never really understood why the low dome exists. If its output across the center of the beam were more even, it would be easy to work with, but the peak at 20-some odd is strange.

The high dome light pattern is simple and easy to work with - light output drops gradually as one pans off the center of the beam.

If you need any other pattern, the side-emitter works great with reflectors.
 

Endeavour

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I just need a very tight beam. What I'm working on isn't flashlight related, so the smaller I can get it, the better.

-EM
 

Topper

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[ QUOTE ]
Endeavour said:
That's the second time I have no idea what you said... /ubbthreads/images/graemlins/confused.gif

[ QUOTE ]
Topper said:
I did not know if I had known I would have Answered quicker than they did Penn. Or Germany, Arkansas is alot closer.
/ubbthreads/images/graemlins/grin.gif /ubbthreads/images/graemlins/grin.gif /ubbthreads/images/graemlins/grin.gif
Topper /ubbthreads/images/graemlins/smile.gif

[/ QUOTE ]

[/ QUOTE ] PM sent
Topper /ubbthreads/images/graemlins/smile.gif
 
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