In article ,
Don Foreman wrote:

A couple of months ago I had an idea for a very compact but efficient
pocket flashlight. The idea was to use an offset-fed parabolic
reflector (like satellite TV) rather than the traditional flashlight
design. Computer models indicated it would work well. Then I got
sidetracked on other things.

I've revisited that with a quick 'n dirty experiment. It seems to
work on the bench as well as in the 'puter.

More at
http://users.goldengate.net/~dforeman/tinylight/

IIRC the military uses some LED flashlights with the LED mounted
'backwards' into a reflector because the beam is so much tighted so it
gets less backscatter in a dusty environment.

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