Sheila, Danny

Today we took about 5 hours out of observing in order to do a series of OMC scans. The measurements were heavily inspired by what Dan Hoak did in alog 22175.

What I wanted to see from these scans was a direct effect of the high spatial frequency optical path distortion on the carrier and 9 MHz and 45MHz sidebands. My attempt to accomplish this required the following:

• Prepare OMC for scanning while locked at 2W RF
• Set up and start 100 second period 70 V amplitude ramp excitation to PZT2
• gather a series of scans at 2W, (also grabbed some scans with 0 DARM offset for contrast defect)
• power up to 5 W after 1000 seconds (for the point absorbers to reach maximum optical path distortion)
• gather scans at 5W for at least 1000 seconds
• power up to 10 W
• gather scans at 10W for 1000 seconds (grabbed scans with 0 DARM offset for contrast defect)

Another separate but relevant measurement was to measure the field content at the AS port with a 35W thermal state. Because we did not want to damage the PD by scanning at 35W we let the interferometer thermalize at 35W and dropped down to 10W to take scans. It is important to note that it was not trivial to power up to 35W on DC readout and transition back to RF hence the large amount of time out of observing. Because of time constraints, the thermalization criteria had to be an hour and a half at 35W rather than 2+ hours which should be good enough for this measurement.

Results from the scans are pending and will be posted in a comment on this log entry.