Re: [ATM] Zernike (or Lyot) phase contrast tests

["Scott Ewart" <scott.e@quicksurfer.com>]

Guy,
    Yes I have seen the test.  A friend built a tester.  It's an extremely
simple device.  And it can be as dim or as bright as you want to make it.
The one I used needed a dimmer to test an aluminized mirror.  You may be
able to use much of your same equipment already used for your Foucault
tester.  You'll need a magnifier.  A finder scope will do, especially if it
has an interchangeable eyepiece for higher power.
    If you're going to build one, you should read Amateur Astronomy #36, p.
48.  It's got a good explanation of how it works and how to set it up.

Scott Ewart


----- Original Message ----- 
From: "Guy Brandenburg" <gfbrandenburg@yahoo.com>
To: <atm@atmlist.net>
Sent: Thursday, June 24, 2004 8:42 PM
Subject: [ATM] Zernike (or Lyot) phase contrast tests


How many people have ever performed one of those
Zernike Phase Contrast Tests to examine surface
roughness? I have just been reading about them in Best
of ATMJ #2 and it all looks fairly easy to make, and
rather useful and informative as well. There is just
one problem: It says that if you want to make a
photograph, you have to make 10-MINUTE exposures with
Kodalith film!!! That must mean that the images are
EXCEEDINGLY dim...

Guy Brandenburg

=====
Guy  BrandenburgWashington,
DChttp://home.earthlink.net/~gfbranden/GFB_Home_Page.html
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