Re: [ATM] LWT setup questions

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

Benard, you might want to consider just using a slit insetead of a pinhole.
Much easier to setup!  Even easier is the slitless setup.  For that you just
put the light source at the bottom area of the KE and look past the top area
of the KE!
The pinhole is really hobslete for doing the Foucault test as you really
only need to have one edge cutting the lightsource to get the same results
as the slitless setup indicates.  Remember that the image is reversed when
coming back to the KE so the edge of the light source returns to the KE
reversed and when you start to cutoff that edge, the shadows happen just as
they would with the pinhole if it was perfectly aligned.  I'll also note
that the pinhole requires a perfect alignment of the eye so that it sees the
pinhole while a slit allows for some vertical movement of the eye without
loss of the image.
FWIW, I've done Foucault tests with just the bare LED without any blocking
device off the edge of the LED's bulb.  You have to be careful for the
radius of the bulb but it can be done!
Bob May
bobmay@nethere.com
http://nav.to/bobmay
http://bobmay.astronomy.net

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