Thanks very much David. That explains what my gut felt; how can emitters do the same job as a filament. Especially in a housing etc. designed for the latter. I'm sure Jim will report back. Neil.
On 7/3/15, David Beierl <dbeierl@attglobal.net> wrote: > Optically they're utterly different from incandescents, Headlights > and such are designed to work with short line sources that radiate > pretty uniformly into a sphere that looks more and more like a > cylinder as they get longer. The only way you can simulate that with > an LED is to map a spheroidal surface some distance away and cover it > with emitters -- but those emitters aren't unidirectional and shining > only outward, they're themselves radiating into some portion of a > hemisphere, so there's a bunch of stray light coming to the > reflectors from the wrong direction. You can make wonderful LED > lights but you have to design for how they work, not use them as > pretend incandescents in existing fixtures. Not a problem for van > cabin lights and such but no fixture with precise optical > characteristics can fail to be degraded. You may well get light > where you want it, or mostly where you want it; but you will also get > light in places where you specifically do not want it. And getting > it where you do want it, uniformly, means mapping onto a larger > surface; where keeping it from where you don't implies going back to > your point/line source. > > Yrs, > d > > >>Neil. > >
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