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Re: [ATM] Foucault images

I get isolated streeks like that correspond to dirt on
the CCD window of my camera.  

Dale Eason

--- Mike Lockwood <melockwo@uiuc.edu> wrote:

> Hi,
> 
> I have added some new images to my Foucault Testing
> Hall of Shame - 
> now there is a "Hall of Fame" at the end of it. 
> Pictured there are my 
> 10" reference sphere and a 13.1" thin mirror I made
> recently.
> 
> One thing puzzles me.  In ALL of my Foucault images,
> there is a 
> vertical texture that shows up which is due to
> something in the 
> imaging system.  It is certainly not on the surface
> of the mirror, and 
> it is there no matter what mirror is tested.
> 
> In fact, the texture sort of rotates as I rotate the
> eyepiece in my 3X 
> scope (which I use on my Foucault tester).  That is,
> parts of it move 
> left and right as the eyepiece is rotated, but the
> pattern itself 
> remains composed of vertical lines.  Cleaning the
> eyepiece has reduced 
> it, but it has not been eliminated.  The effect is
> not really apparent 
> to the naked eye, but when my digital camera is used
> to take images 
> through the scope, it can be seen.
> 
> To the eye, the mirrors are REALLY smooth, and any
> hints of the 
> vertical structure move as you move your eye around.
> 
> Here's a link to the page:
>
http://bi-staff.beckman.uiuc.edu/~melockwo/mirror_making/foc_hall/foc_hall.html
> 
> Here's a shorter link to my home page - you can also
> reach the 
> Foucault page by clicking on the link there:
>
http://bi-staff.beckman.uiuc.edu/~melockwo/index.html
> 
> Enjoy the photos - scroll down below the "Hall of
> Shame".  I have 
> described them as completely as I can to indicate
> the differences 
> between the images I captured and how it appears to
> my eye.
> 
> If anyone as thoughts on where the vertical
> artifacts are coming from, 
> please post a message to the ATM list.  I suspect
> the fact that both 
> the slit and the artifacts are aligned vertically is
> not a coincidence.
> 
> 	Mike Lockwood
> 
> _______________________________________________
> ATM mailing list http://www.atmlist.net/
> 


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