nutsinee.kijbunchoo@LIGO.ORG - posted 17:01, Thursday 31 January 2019 - last comment - 16:12, Monday 04 February 2019(46730)
SQZ Pump power intensity servo is working (again)
Daniel, Nutsinee
We had been using OPO common mode board for the intensity servo until we swapped the scheme (now the OPO CM board is actually used to lock the OPO). The servo is now all digital with a UGF of 200Hz. H1:SQZ-OPO_TRANS_LF_NOM has to be set to 1. The output (2nd from the left of SQZ rack U16) goes through a 450 Ohms resister and to the IFR that drives the AOM.
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We found a filter that wasn't supposed to be on (an anti-whitening for a build-in whitening filter inside a PD, which OPO refl doesn't have). Fixed the mW2V gain (now 40) and the UGF of the intensity loop is now 100Hz. It no longer glitch when we turn the loop on. We also found that the whitening filter was turned off, which worked for the analog setup we used to have.
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