Don Foreman wrote:

Please keep us posted on your progress in making one that is even
better. Your use of a sapphire lens as a heatsink is interesting.
I don't see much advantage in a retroreflector, but one issue I had
with that concept was heat transfer which your scheme neatly solves.
Streamlight, I think, offers the "recoil" which is a retroreflector
but I wonder how or if they accomplish heatsinking without fragility.


It's Pelcan that makes the M8 and 2020 Sabrelight. They call it the
'recoil' system.

They use a cheaper lens and mount the LED on an aluminum support. The LED
is only running at 1 watt, so there's not a lot of heat to dissipate.
The support is thin but deep, so it can support the LED and conduct the
heat away.

The pelican recoil lights are made for diving and rescue work where
there is smoke or silt to obscure your vision. Light that spreads out
will reflect off the silt (or smoke) causing glare caled backscatter
that make it harder to see. The recoil beam is so concentrated that
it illuminates an 18 inch by 18 inch square at 15 feet with virtually
no light outside that square. Yes, I have one in my collection.

Optics are another way to concetrate the light without having a large
reflector. There are many makers of optics just for LED lights.
I have a 10 degree optic on the light in my pocket. It's only 17 mm
across and less than that deep. If the retroreflector does not pan out,
optics may be the answer.

Daniel