On Thu, 11 Sep 2008 09:38:46 -0700 (PDT), Art Unwin
wrote:

On Sep 11, 10:37*am, Richard Clark wrote:
On Thu, 11 Sep 2008 06:18:14 -0700 (PDT), Art Unwin
wrote:
If I have a flash light that is focussed does this wavelength aproach
still apply?

The reflector (or magnifier lens, take your pick) is on order of at
least 1 centimeter. *The light wavelength is on order of 500
nanometers.

Ratio = 20,000:1

Beam is generally no narrower than 15 degrees. *At a distance of, say,
6 feet, that beam would cover a diameter of 18 inches. *Nothing like a
Lazer (sic) if that is the goal.

I see no basis for the inclusion of wavelengths when one is not using
a straight radiator

Read your own question. There is no such thing as a "straight
radiator" of light. There is everything to do with wavelength or you
could never see light.

73's
Richard Clark, KB7QHC