# the emitter with the highest surface brightness



## Nos (Mar 10, 2009)

Hi guys, im about to build my ultimate mag aspheric, but i dont know which emitter is the best for it. basicly there are three emitters :shrug:


Cree xr-e R2 with 242 lumens at 1A, here driven @1400ma (max from spec is 1000ma)
Cree xr-c P3 with 80 lumens at 0,5A here driven @700ma (max 500ma)
Luxeon K2 220 with 300 lumens at 1,5A here driven @1800ma (max 1500ma)

what will give the best results? :huh:


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## LukeA (Mar 10, 2009)

One you may want to consider is the XP-E. It has as many lumens as the XR-E, but projects them from a smaller apparent area. 

This comparison isn't as easy as it sounds. You have to take into consideration the better beam patterns of the XR-E and XR-C against the high lumen level of the K2 and the relatively small apparent die size of the XP-E.


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## Nos (Mar 10, 2009)

hmmmmm i didnt even consider a xp-e into because i allready had the chance to compare it to a xr-e side by side, both r2.
the projection of the xpe is only a hint smaller, unsharp and not brighter than the xr-e. 
and till the xp-e is 700ma max rated i cant push it any further 

:candle: any other experiences? :thinking:


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## LukeA (Mar 10, 2009)

Nos said:


> hmmmmm i didnt even consider a xp-e into because i allready had the chance to compare it to a xr-e both emmiters R2 bin side by side.
> the xp-e projection of the xpe is only a hint smaller, und sharp and not brighter than the xr-e.
> and till the xp-e is 700ma max rated i cant push it any further
> 
> :candle: any other experiences? :thinking:



So a smaller apparent die removes the XP-E from consideration? And the only one of those LEDs you can't overdrive is the XP-E? What do you think the rated drive currents are for the XR-E and XR-C? How about the K2?


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## mash.m (Mar 10, 2009)

this days i testet the new k2 with 300l max @ 1500ma, but it is not so bright then a cree q5 at 1000ma. i can´t belive this so i send back the emitter to the supplier. they check the led and everything seems to be ok.
i have ordered a new k2 300l max led from an other supplier to compare.maybe the first one is a fake.
tomorrow i make some pictures that will show the k2 and the cree with a aspherical lens.

markus


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## Nos (Mar 10, 2009)

hmmm. maybe that was a bit unclear.

i have 2 aspheric mags lieing here, one uses an XR-E the other one a XP-E.
the smaller apparent die of the XP-E produces a 2cm smaller die at the wall than the XR-E mag @ 2,5m.
Brightness is the same :ironic:




but the main reason why i wont take a XP-E is because it isnt any better than a xr-e at 1A.
And since the max current of a XP-E is only 700ma, 1A is driving it really hard.
equal to a XR-E @1,4A (allmost exactly the same factor)

and a XR-E @1,4A beats the XP-E @1A for sure 

the XR-C with its tiny die will be far more interesting...but i doubt that it can take 1A (its 500ma max) ill correct that to 700ma and add the max current from the specs.

I guess the battle will be K2 or XR-E ....... but i have no idea which will do better in a aspheric setup


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## Nos (Mar 10, 2009)

Hi Markus, sorry to hear about the poor performance of the (maybe fake) K2.

Lets hope the next one will do better, im looking forward to your pictures


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## SemiMan (Mar 10, 2009)

I would go with the XRE versus XP-E or K2. The XRE has a much narrower emission angle. A lot more light will hit the lens.

Nos, when you compared the brightness, was that by eye-perception or actually measured?

Semiman


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## HarryN (Mar 10, 2009)

mash.m said:


> this days i testet the new k2 with 300l max @ 1500ma, but it is not so bright then a cree q5 at 1000ma. i can´t belive this so i send back the emitter to the supplier. they check the led and everything seems to be ok.
> i have ordered a new k2 300l max led from an other supplier to compare.maybe the first one is a fake.
> tomorrow i make some pictures that will show the k2 and the cree with a aspherical lens.
> 
> markus



I am just curious - how in the world did you properly install a K2, including soldering it in and proper heat sinking if you could then send it back to the supplier ? 

Please don't tell us that you used some arctic silver grease without a mechanical hold down and this is the basis for the comparison. :sick2:

Make sure you are getting the TFFC version.

Moving on, the K2 has a lambertian shaped output (more or less - emits every direction). If you are going to depend on the lens, then the only light reaching it is what comes from the front. Light from the sides is more or less lost.

An aspherical lens will perform best with an LED package that has practically all of the light come directly from the front (narrow beam pattern) even if the total light is less.


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## Nos (Mar 11, 2009)

SemiMan said:


> I would go with the XRE versus XP-E or K2. The XRE has a much narrower emission angle. A lot more light will hit the lens.
> 
> Nos, when you compared the brightness, was that by eye-perception or actually measured?
> 
> Semiman



I have no lux meter at moment :shrug: but comparing those two side by side with the bare eye, is not exact but should be ok :sigh:


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## mash.m (Mar 11, 2009)

hi,

the led is mountet on a star. under the star some paste and then two screws on a copper block. so removing is no problem remoing and send back!

so here now the pictures to compare. left mc-e at 1000ma/die right k2 tffc 300lm 1500ma:






left mc-e warmwhite 1400ma/die, middle k2 tffc 300lm [email protected] 1500ma and right k2 tffc 300lm [email protected] 1500ma:





so i think the first k2 is wrong or a fake. i will contact the supplier with this facts.

here a picture at 2000ma k2 vs k2:





markus


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## Nos (Mar 11, 2009)

hey nice pics Markus :thumbsup:
the K2 knocks the MC-E out for sure (was obvious) do you have a XR-E @1,4 that you can compare directly to the K2 @2A?

btw, do you know the colour bin of the cold white MC-E, it looks pretty cold compared to the K2


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## HarryN (Mar 11, 2009)

Hi Marcus - thanks for the information and pictures. 2,000 ma into the K2 - wow.

The (good) K2 TFFC stars you have are certainly brighter than what Future is selling, especially in the star format. Interestingly, the emitters they have for sale are pretty good. 

Where did you get them if you don't mind my asking ? 

It almost appears that the "not as good" K2 TFFC is getting more dim with increased current - or is that an optical illusion ?


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## mash.m (Mar 12, 2009)

you are right - "K2 TFFC is getting more dim with increased current"

at this moment i will not offer the name of the supplier, cause i wan to wait for the answer. but it is the most popular led dealer here in germany!

the good one is from www.dotlight.de

markus


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## mash.m (Mar 12, 2009)

so here now the compare q5 vs. k2

upper both @ 700ma
middle both @ 1500ma
lower both @ 2500ma






the q5 can handle this high power with good heatsink. others here at cpf also use the cree at this high power. i think for 1000 hours it is ok. the k2 have the more beautyfull die.

hope this picture help you with your choice.

markus


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## Nos (Mar 12, 2009)

thaks a lot, that review really helped me a lot


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## mash.m (Mar 12, 2009)

cheers


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## AlexGT (Mar 12, 2009)

Do you have a guess at how many lumens are you getting at 2 amps with the K2?


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## mash.m (Mar 13, 2009)

don´t know, but i think 350lm are real


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## Tatjanamagic (Mar 17, 2011)

Hmm I think that emitter with highest surface brightness is R2, Q5 is almost same but R2 is better...


However I would be happy if U find better emitter for aspherical lenses.

In fact please add your consideration and any news about led emitters here.

Thanks.


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## Nos (Mar 18, 2011)

Its funny reading this thread years later again. And still the XR-E seems to be the king.


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## flatline (Mar 18, 2011)

I would guess it's because the driving force behind LED development is lumens/watt, not throw.

Just a guess.

--flatline


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## saabluster (Mar 18, 2011)

Nos said:


> Its funny reading this thread years later again. And still the XR-E seems to be the king.


 You sure about that?


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## Tatjanamagic (Mar 19, 2011)

saabluster said:


> You sure about that?



Saabluster you are God of aspherical flashlights.

Please tell us your opinion which emitter has highest surface brightness.


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## srfreddy (Mar 19, 2011)

I think the SST-50 overdriven to 9 amps would certainly have higher surface brightness....


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## Walterk (Mar 19, 2011)

Tatjanamagic said:


> Saabluster you are God of aspherical flashlights.
> 
> Please tell us your opinion which emitter has highest surface brightness.



He used the Cree XRE for the Deft for a reason. Now the Cree XML is quite 'hot' and promising. See: Why a good thermal path really matters 

And:
Die luminance, emittance and advanced die heatsinking*
*Formula for calculating throw using aspheric lens


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## archer6817j (Mar 19, 2011)

Mash.m, what kind of aspheric are you using in those photos?


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## saabluster (Mar 22, 2011)

Tatjanamagic said:


> Saabluster you are God of aspherical flashlights.
> 
> Please tell us your opinion which emitter has highest surface brightness.


 
Thank you for the commendation but I am uncomfortable being called the god of anything much less the *G*od of something. That would be reserved for the Almighty. 

I do believe we have a new winner but before I post my results I want to be absolutely sure of what I am speaking. I am in the process of building myself a high precision integrating sphere. I will do some tests in that first and report back my findings.


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## Tatjanamagic (Mar 24, 2011)

U can not be the God but you are the King of aspherical flashlights that nobody can deny...

I am looking forward for your report.

Plenty of people here think that there is no future for aspherical flashlights... I am glad that there are people constantly trying to improve their product.

Ideal aspherical flashlight for me would be with adjustable focus, acceptable size and with nice round beam throwing blinding clearly up to 400 meters, and of course gun mountable.

With new emitters coming that dream could became achievable.


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## saabluster (Mar 24, 2011)

Tatjanamagic said:


> U can not be the God but you are the King of aspherical flashlights that nobody can deny...
> 
> I am looking forward for your report.
> 
> ...


 Other than the round throw beam all these are possible now. It is of course possible to have the round beam but not in the highest throw situation. For that we are beholden to the shape of the die. I've had a unique adjustable focus mechanism for aspherics for almost two years now but not the time or money to implement it.


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## Tatjanamagic (Apr 9, 2011)

I have talked With Deerelight costumer support and they have told me that [FONT=&quot] XR-E R2 is still the king of throw in the asphrical lenses...

Saabluster do U have something new on this theme? 
[/FONT]


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## gcbryan (Apr 9, 2011)

Tatjanamagic said:


> I have talked With Deerelight costumer support and they have told me that [FONT=&quot] XR-E R2 is still the king of throw in the asphrical lenses...
> 
> Saabluster do U have something new on this theme?
> [/FONT]



It's because it still has the highest surface brightness. All the newer emitter just get getting larger rather than brighter (lumen rather than lux goes up).


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## znomit (Apr 9, 2011)

gcbryan said:


> It's because it still has the highest surface brightness. All the newer emitter just get getting larger rather than brighter (lumen rather than lux goes up).


 
XR package throws more light out the front too, making it better for aspherics.


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## John_Galt (Apr 9, 2011)

znomit said:


> XR package throws more light out the front too, making it better for aspherics.


 

Exactly, a narrower viewing angle is better when working with Aspherics.

I wonder how well the XP-G would throw/perform if it came out in the XR package, instead of the XP package. AFAIK, it would be easier to heatsink/have more effective heat transfer from the die to heat sink... And the narrower viewing angle would be great for the variety of optics out there for the XR-E, as opposed to the XP-E.


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## znomit (Apr 9, 2011)

ps I always thought that the XR-C had the highest surface brightness.


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## saabluster (Apr 10, 2011)

Tatjanamagic said:


> I have talked With Deerelight costumer support and they have told me that [FONT=&quot] XR-E R2 is still the king of throw in the asphrical lenses...
> 
> Saabluster do U have something new on this theme?
> [/FONT]


 I do. znomit was very close. It is the XP-C. One has to be clear what is being said when talking about which one has the highest surface brightness as it depends on what the ground rules are. Are we talking about at a matched specific drive level, the max suggested drive levels for each respective LED, or the absolute potential which comes with overdriving? 

I tend toward the absolute limits when making a determination because if you say LED A has more than LED B when they are both @350mA but LED B can be driven far far harder and be more intense than LED A at its limit then the prior declaration is up for dispute. The best LED I have tested to date is the Q4 binned XP-C. The XP-E HEW may do well but I haven't had a chance to test it yet. I was wanting to get my hands on the R5 binned XP-E HEW before I made my proclamation but you guys just can't seem to wait around here. I doubt the HEW will be able to do it because of what I have heard about the phosphor deposition technique. I have some R4s in hand but have not tested them yet. So for now I feel fairly confident in saying the XP-C takes the cake.


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## MikeAusC (Apr 10, 2011)

Do you mean Surface Brightness - or Effective Surface Brightness ?

Do you plan on de-doming the LED ? If so, then you can compare LEDs based on the brightness of the phosphor.

If no de-doming, then you need to compare them based on phosphor brightness AND how widely the lens spreads the phosphor image - if the beam angle is 40% wider, the light from each particle of phosphor will be spread over twice the area, reducing effective brightness.


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## videoman (Apr 10, 2011)

saabluster said:


> Other than the round throw beam all these are possible now. It is of course possible to have the round beam but not in the highest throw situation. For that we are beholden to the shape of the die. I've had a unique adjustable focus mechanism for aspherics for almost two years now but not the time or money to implement it.



Perhaps not for flashlight discussion, but I have some info. on fresnels and aspherics on 2 recent applications using them.

Adjustable focus light units have ( on-camera video lights ) recently brought to market, as 2 newer models have been shown to be very popular because of that feature. One model uses 2 lenses (aspherics) and the other model uses a single fresnel of arounf 3mm in thickness in front of the led. Both models have a single led in them. Perhaps a fresnel can definitely be used for the focusable feature. I am sure it has been done on a flashlight before as fresnels are over a century old, but having one on a XM-L should be awesome. In the fresnel model light http://www.litepanels.com/sola_eng.html that is achieved by rotating the front bezel to distance the fresnel from the led similar to a camera lens as it is being focused closer. It is a matter of male/female circular threads. Same principle for the aspheric unit http://www.dedolight.com/www/dedoli...000004OO&id=DL_Ledzilla&mode=search&section=0 That varies the angle from 4 to 56 degrees.
If fresnels prove to be effective, then perhaps there is a market for a focusable fresnel flashlight, I myself was looking for the holy grail in the design of my video light using fresnels, but sourcing the proper size was almost impossible and the added mechanical design of varying the small distance change from the led to fresnel surface was too much of a challenge. Please keep us up to date of your design , as I am sure that would surely be a welcome feature.


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