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Entry  Mon Aug 16 14:19:00 2010, Alastair, Laser, GYRO, Changed to Marconi on AOM gyro_transmission_08_16_10.pdf
    Reply  Mon Aug 16 15:31:27 2010, Zach, Laser, GYRO, Changed to Marconi on AOM 
    Reply  Tue Aug 17 10:18:02 2010, rana, Laser, GYRO, Changed to Marconi on AOM 
       Reply  Tue Aug 17 15:34:02 2010, Alastair, Laser, GYRO, Changed to Marconi on AOM gyro_transmission_08_17_10.pdf
          Reply  Wed Aug 18 03:01:23 2010, rana, Laser, GYRO, Excess noise mystery resolved 
             Reply  Wed Aug 18 10:31:28 2010, Alastair, Laser, GYRO, Excess noise mystery resolved 
Message ID: 937     Entry time: Mon Aug 16 15:31:27 2010     In reply to: 936
Author: Zach 
Type: Laser 
Category: GYRO 
Subject: Changed to Marconi on AOM 

It is so great that we have a working readout now so we can monitor our sensitivity in real time. Now that we have this, we have to systematically go through and make each component quieter until we get sensitive enough to see one of our expected sources. When I get back I'll hook up with Rich to get started on the RFPDs. I am betting that a huge amount of our noise is coming from their absence. We should also have a think about if and how we need to modify the PDH boxes. I am a little out of the loop by now, but it will be nice to get back into the swing of things.

I gave a lunch talk about the gyro here at LHO today, and I was happy to report our getting within 106 of design sensitivity ;-)


I borrowed a second Marconi from Frank this morning to check whether the Tektronix driving the AOM was our main noise source.  As you can see from the plot the noise was virtually identical using the Tektronix.  I also (accidentally) took data with the modulation input on the Marconi switched off, but the carrier on (so the CW loop was resonant in the cavity still) - interestingly the noise was quite a lot lower - I need to think a bit more about this, but it gives an indication that certain noise sources are not the main ones at the moment (certainly the Mach - Zehnder readout isn't the dominant noise source).  I also took the lid off the box and remeasured - the noise below 3Hz was worse.  It is up about a factor of 10 at 0.01Hz.  Nice to know our box is doing something for us.

I'm going to pass this Marconi back to Frank now.  I'll try to find a replacement from the 40m if there is a spare one after the phase measurements.


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