Re: ATM Foucault tester light source....

["Bob May" <bobmay@nethere.com>]

The brightness of the light kind of depends upon where you are doing your
testing.  If you need to do the testing in sunlight, a very bright light
would help such as the Halogen light and a bit of light pipe.  For most, a
LED is more than bright enough to get excellent results in a dimmed room.
The purchase of an ultrabright LED (chose a color you like to look at as
they all will be more than bright enough and the test doesn't care what the
color of the light is) and run it at a brightness level that doesn't make
your eye hurt when you look at the mirror and you will be happy.
I'll note that white light is not necessary to view the results and if you
use a B&W camera to view the results of the test, you won't see the color
anyway.  I've used red, yellow and green LEDs and tend to prefer the yellow
LED for doing the test with my eye although the red is right behind in
acuity of the test as either color is easily focused with my eyes.
Bob May
http://nav.to/bobmay
bobmay@nethere.com
NEW! http://bobmay.astronomy.net