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Entry  Thu Dec 6 02:55:46 2012, Den, Update, Alignment, c1ass xarm_ass.pngyarm_ass.png
    Reply  Fri Dec 7 00:08:39 2012, rana, Update, Alignment, c1ass 
       Reply  Fri Dec 7 02:02:23 2012, Den, Update, Alignment, c1ass 
Message ID: 7797     Entry time: Fri Dec 7 02:02:23 2012     In reply to: 7796
Author: Den 
Type: Update 
Category: Alignment 
Subject: c1ass 

I suppose that there is also a similar system possible to align the arms in a continuous way; i.e. low level drives and very low bandwidth. Also something fast / slow for the the DRMI.

 c1ass was really useful today when we slowly aligned PZT and servo kept arms aligned to the input beam. I think it is possible to automate phase and matrix measurements. DRMI servo will be very useful.

Today I tried to investigate the mode in PRCL and MICH. I locked them but power build-up was only 27. The beam on the POP camera looked like interference of 00 mode and a long strip of fringes. (I wanted to make videocaptures but script is not working - the problem is that it is looking for /usr/lib/*.so.4 libraries but they were updated to *.so.5, I made a few links .so.4 -> .so.5 but this kept going for many libraries, so this should be fixed in a better way). 

We looked at PRM and BS faces and they had the same shape - interference of a circle with a strip. There were also a lot of bright spots all over the frames. Loops were closed and circle was not moving. Strip was oscillating at ~1Hz and also its position significantly changed with alignment. Looking at PRM face camera we made a conclusion that the length of the strip is ~5 cm and width ~1cm. Interesting that strip has plenty of power - approximately 10 times of transmitted beam when cavity is not locked. As a result POYDC was oscillating at the same frequency as a strip.

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