In , Lostgallifreyan wrote:
(Don Klipstein) wrote in
:

There are some high power IR laser diodes more efficienct than
LPS.
Other than those, laser diodes are less efficient than most sodium
lamps.

Ok. I thought more laser diodes were but never mind.. Aren't most
class 3B visible red diodes around 20% efficient or more though? That
still leaves a lot of headroom. Tungsten is often said to be 1% to 2%
efficient at making visible light. So a 100W incandescent 17 l/W at 1%
to 2%

More like 6-7%. Each watt of tungsten radiation in the 400-700 nm
range
is around 250 lumens.

places the Cree XR-E's 50+ l/W at 3 times that, up to 6%.

Figure around 250-300 lumens per watt of "white LED light". Looks
like
those achieve about 20%.


Watts of emitted light? I just saw a later post of yours that mentioned
"lumens per visible radiated watt". I think that's why we're discussing
such different values. I'm talking about input watts. I thought we all
were, at least Eeyore certainly was, as that's ultimately watt (haha) is
consumed no matter watt is emitted.

Cree themselves don't claim anything like 250-300 l/W for input watts, at
least not yet, though that might not be long awaiting.

So how does a 100W incandescent look in that context?

I am saying that a watt of white light is about 250 lumens, not the 683
some use as the lumen/watt figure for a 100% efficient light source. A
100% efficient white light source would achieve about 250-300 or so
lumens/watt, depending on what they call "white".

Most of those generating figures of incandescents being 1-2% efficient
are assuming that they would achieve 683 lumens/watt if they were 100%
efficient.

- Don Klipstein )