The ATM session on 1/7/12 was very interesting to say the least. First, Charlie has his 13" mirror mounted in a 17" Coulter mirror/rocker box with truss tubes and top ring complete (at least for star testing). He hopes to star test this week sometime when the skies are clear. His goal with this is to rule out astigmatism. Both Josh and Charlie center dotted their mirrors. The bulk of the time, and it was a lot of time , was spent trying to get the "spot test" to work. See this link: http://www.john-pix.com/a/spot.html for a discussion on the spot test. It is basically a 2-dimensional version of the knife edge test and so can more thoroughly test mirrors, especially for things like astigmatism. We were hoping that we could test Charlie's mirror for astigmatism with this method. The short answer is that we were never successful in getting the test operational. It was easy getting nice, clean, round pinholes, but getting a spot to line up and work properly was elusive. In the end we determined that the pinhole and spot need to be mounted independent of each other on their own X-Y stage. It was a fun, but fruitless time. At least we know how not to do the spot test! Josh showed us his recently acquired materials to make a bath interferometer and once that gets going, it will be a powerful bench test tool. Keep walking the barrel! Mat ---------------------------------------------------------------------------- This message and any included attachments are from Siemens Medical Solutions and are intended only for the addressee(s). The information contained herein may include trade secrets or privileged or otherwise confidential information. Unauthorized review, forwarding, printing, copying, distributing, or using such information is strictly prohibited and may be unlawful. If you received this message in error, or have reason to believe you are not authorized to receive it, please promptly delete this message and notify the sender by e-mail with a copy to Central.SecurityOffice.Healthcare@siemens.com Thank you