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Message ID: 57     Entry time: Sun Feb 7 20:56:03 2010
Author: Frank 
Type: Laser 
Category: RefCav 
Subject: AOM power modulation & pointing 

seems like a bad AOM and an impedance matching problem together. exchanging the semi-rigid cable by other cables produces a lot of different results in power modulation / pointing vs frequency. right now i found a combination where for frequencies 80MHz and higher it is almost flat, but below it drops a lot. the pointing is related to the absorbed power in the AOM. - you can really feel the heat of the crystal, no joke. will measure the temp on tomorrow for different frequencies where the pointing is worst case to see if it is a macroscopic change in temp. Aidan has this nice thermal image camera to do this. i think we should try the crystal technology AOM we have. i don't think that aligning helps a lot here. tried this the whole afternoon :-(  the lowest power modulation over the entire frequency range is about 20%pp


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