Emitter/Reflector compatibility ?

[GarageBoy]

Is it possible to use, for example, a Luxeon I/III reflector with a, say..XPG emitter and still achieve perfect focus (with shims or w/e), or are old reflectors "obsolete"?

 

[BigHonu]

I vaguely remember someone using a McR20 or something similar and achieving pretty good focus with the XP-G, but the emitter needed to be backed out a bit and was very sensitive to positioning.

 

[fyrstormer]

Parabolas are never obsolete.

 

[GarageBoy]

Yes, but I was wondering if they are cross emitter compatible due to different dispersion angles and focal heights of the dies on different LEDs

 

[fyrstormer]

As far as I know, only the Cree XR-E requires a different parabolic curve because the integrated lense above the emitter pre-focuses the beam so it doesn't match an ideal lambertian dispersion pattern anymore. The McR20 should work fine for any emitter with a true lambertian dispersion pattern (not just mislabeled as such, like Cree XR-Es are); as far as I know, the only difference between the different McR20 reflectors is the location of the focal point, which is easy enough to adjust for if the hole is big enough to let you move the emitter around a bit.

 

[PoliceScannerMan]

Class is in session, I'm ready to learn.

 

[Th232]

Pretty much what fyrstormer said, the reflector will still work for any lambertian LED, but you may need to put a shim in place or cut away part of the reflector. I believe that when Don had to change the LS20 from using Rebels to Golden Dragons he had to trim the reflector down a smidgen. Note that there will be size restrictions, I suspect that enlarging the hole in a McR12 for use in, say, an SST-90 would be rather pointless.

The McR20 should work fine for any emitter with a true lambertian dispersion pattern (not just mislabeled as such, like Cree XR-Es are)

Curious, how are they mislabelled? If you're saying that XR-Es are called Lambertian emitters in the documentation, that's the first I've ever heard of it. Maybe I've missed something, but a quick scan of the XR-E datasheet and the Cree website doesn't even bring up the word "lambertian". The XR-E datasheet explicitly says that the viewing angle is 90 deg (as opposed to a Lambertian distribution which is ~115 deg), and the spatial distribution graph definitely doesn't look Lambertian.

 

[fyrstormer]

It's not so much the emitters themselves, but some lights that use them mistakenly describe the beam pattern as lambertian. Anyway, as long as we all know that isn't the case...