Cree SC5 platform, XHP LED's

[easilyled]

Thanks, thijsco19. It seems that smooth reflectors should not be used with these emitters then.

 

[Epsilon]

Have you tried to change the focus Thijsco? Or is this the best result you got from the led/ reflector combo?

 

[vestureofblood]

I've mod a convoy L5 host with a XHP50 led. It has a smooth reflector and yes there is still a 'dark spot' in the middle of the hot spot.
I'm not sure if that's because I couldn't focus the led properly or because it's just the quad die layout itself.

It seems that smooth reflectors should not be used with these emitters then.

Here is my 2 cents. After having used a handful of XHP-50 and 70s it does appear that the nearly forgotten doughnut has reared its ugly head a bit once again.

I first noticed it when I started mocking up the Copper P60 XHP-70. I use a OP reflector in this which has always delivered an exceptional beam with any of the modern emitters. However with this I did notice a slight dark spot in the middle.

I also made a 3x XHP-50 set up with a deep set of SMO reflectors and the result was significantly worse.

For this set up I used some of the typical XML LED isolators to set the height. The ones with the little square cut in them that look sort of like a bow tie ( which focus XML perfectly).

Here is the beam profile with that setup.


I thought that was pretty nasty for a multi emitter set up. It was a fairly small doughnut but quite dark and noticeable I thought.

I had previously discovered with the OP reflector that changing the height was an effective fix for this. Here's the thing though. Often in times past to change focus moving the reflector OUT from the emitter was the thing to do. In the case of the P60s and the 3 XHP the opposite was true.

In order to remove the doughnut with a reflector made for an LED with XHP emitters you need to move the emitter DEEPER INTO THE REFLECTOR.

I spent some time machining off the base of the reflectors, in both cases this fixed the problem.

Here is a profile shot of the 3x XHP-50 light with the reflector shortened.





As you can see its still not MT-G2 quality, but in real life to my eyes it looks like about an 85% gain.


With the XHP-50s in my small single reflectors I found that simply setting the reflector down flat around the emitter was a usable solution ( not perfect, but better, a little higher is better than this). That is not possible for the 70s but with the removal of between .020 and .040" from the base to lower the reflector I get a usable beam from any of the XHPs with any reflector I have tried ( which is only a few at this point).

Happy modding friends!

 

[easilyled]

.... Here is my 2 cents. ...... !

Thanks for all the learned info. A lot more valuable than 2 cents!

It does make me wonder whether there is much to be gained by using these XHP emitters in flashlight applications when they have to be effectively defocussed in order to eliminate a donut that is not present in the other emitters currently used.

Sure they are currently the brightest in a single package, but not really much more efficient than the other emitters as far as I know. The brightness comes at the expense of extra energy expended.

So perhaps it would be better just to use multiple XM-L2s or MT-G2s to achieve the same brightness but without donuts when such a high level of brightness is required?

 

[vestureofblood]

I would say that the key advantage to XHP-50 is that it sits directly on the foot print of an XML MCPCB. For me this has proven to be an easy way to pack more punch into many existing templates. As far as beam quality the MT-G2 still by far reigns supreme.

 

[Epsilon]

Thanks vestureofblood for the in depth feedback!

Not the news I was wanting to hear, I'd rather had heard that the weird looking dome on the LED was doing its job and there was no donut .
Well, we'll see. Have two coming my way at this moment and a smooth reflector that works beautifully with an MT-G2 so I can compare those two.

Cree better make a 3*3mm2 die (SST-90 size) LED in this formfactor .

 

[thijsco19]

@Epsilon. Nope, I am planning to do so, thnx to vestureofblood I now know what I need to do .

A nice vid of showing the beam pattern of the XHP70 (not mine vid)

 

[mcfarlie6996]

This little XHP50 is an excellent candidate for those already using the XML2 Easy white (6V) as the 6V version of XML2 suffers from lower efficiency compared to the low voltage version. I plan to upgrade my motorcycle DRL lights using XHP50 soon!!

Where do I go to find this graph/chart?

 

[mds82]

Where do I go to find this graph/chart?

http://pct.cree.com/dt/index.html

 

[dkemppai]

I'd rather had heard that the weird looking dome on the LED was doing its job and there was no donut .

FWIW, This may be a little late. I can confirm the Eagtac MX25L3 with XHP50 does have a donut. It's not horrible, but is present at medium ranges. Close up it isn't detectable, and is harder to see at long distances. For me, the throw combined with total amount of light at 300+yds make up for it.

Dan

 

[tex.proud]

Came across this old thread while searching for info on the XHP after noticing that ArmyTek is getting in on the action.

https://www.armytek.com/be-the-first-to-say-wow.html

I was looking for a headlamp. Guess I found the one I want.