Hi Ian,

I did the exact same experiment last night and we got similar results
I think. There are some problems however::

The biggest problem is that the inside of the enclosure is not
mirrored, so the pie tin would shine a good portion of the light
upwards....never to exit at the bottom...in effect, creating a black
hole.

The losses are quite severe even though the paint inside is shiny
white.

In my particular cans, the top is open and some light exits through
the top-so any light reflected back 'up' would be wasted.

The system you are referring to is called a Cassagrain Feed and it's
used to feed microwave dishes and for telescopes. It only works when
the surface of the reflecting surfaces are nearly perfect, or else the
losses from the additional reflector take a big chunk of the output
and waste it.

This issue of the quality of the reflectors is even more critical in
an ap such as this-some of that light will take 4 or 5 bounces before
it exits, depending on the design of the radiator and the reflectors.

A new design with a no compromise reflector system would work well,
but I'm not seeing anything along those lines when I look in lighting
catalogs.

Art in Maine


Further exhaustive testing with small aluminium pie tins, and a couple of
bits of paper-clip indicate that there might be a fairly simple solution.
Put the pie-tin so that it's 1-2cm below the bulb end, and extends 1-2cm
out from the tip, held there by hooks onto the bulb glass.



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