Re: [ATM] TDE on a 6f6 mirror

["Anthony Anconetani" <anthony.anconetani.atm@gmail.com>]

Good evening guys,

Vladimir, thank you for looking at the pictures. Yes, a bunch of
things changed between picture 1 and 2. I wasn't so much interested in
explaining the difference between the two pictures. Rather, I was
guessing that the bright left side could be a reflection from the
inside side of the mirror. But the more I think about it, the more I
suspect the edge is just turned down.

Dale and Mike,

Well, I took two more pictures at about zone 2. Here is the first with
the knife edge backed out.

http://www.atmlist.net/contrib/anthony-dot-anconetani-dot-atm-at-gmail-dot-com/zone2_no_knife_crop.JPG

It doesn't look to me like the the camera is vignetting the light
cone. I think that dark edge on the right is rolling down. Is that
what you think Dale?

Here is the second picture with knife brought in:

http://www.atmlist.net/contrib/anthony-dot-anconetani-dot-atm-at-gmail-dot-com/zone2_crop.JPG

This picture still bugs me. Without the camera, the rolled edge/TDE
doesn't look as bad and I can see a faint diffraction on the right.
Are digital cameras a little more pesimistic (or maybe unbiased 8-)
then eyes?

Mike,

You mentioned astigmatism. Looking at the picture zone2_crop.JPG is
lumpyness causing the astigmatism? Or do you see a bigger problem?

What's the difference between a "rolled edge" and a "turn down edge"?

Lastly, yeah blue LEDs... Too Cool...  I got that idea from some guy
up in Illinois. 8-) Actually, I saw them in DigiKey and couldn't
resist.

-Anthony, Round Rock TX

On Nov 19, 2007 4:02 PM, Mike Lockwood <melockwo@uiuc.edu> wrote:
> Hi,
>
> Dale Eason wrote:
> > There is the possibility that the camea lens is
> > vignetting the right side of returning light cone.
> > That happens a lot with small cameras with zoom
> > lenses. It can also happen if the camera lens is not
> > close enough to the knife.
>
> Good point.
>
> > To know for sure back the knife out of the image and
> > then take a picture.  If the mirror is not fully
> > illuminated then that is indeed the case.  If the
> > mirror is completly lit then then edge is turned.
>
> Let me add to that - IF the mirror is completely lit then you have a
> rolled outer ZONE, as well as TDE.  You also have some astigmatism
> because the shadows are not symmetric, and/or possibly roughness or
> turbulent air in the testing room.
>
> Let's hope that the mirror was not fully lit and the next set of
> photos is better.
>
> I like the blue color.  :)
>
>        Mike Lockwood
>
>
> _______________________________________________
> ATM mailing list http://www.atmlist.net/
>
_______________________________________________
ATM mailing list http://www.atmlist.net/