jeffrey.kissel@LIGO.ORG - posted 12:04, Wednesday 20 July 2016 - last comment - 15:23, Thursday 21 July 2016(28527)
TCSY Delivered Laser Power -- The Day After
J. Kissel, E. Hall Checking in on the power delivered to the ITMY compensation plate after the strange drop in TSCY's front-end laser power drop yesterday (see LHO aLOG 28506), it looks like the laser power has recovered, mostly. The power, as measured by the pick-off beam just before the up-periscope into the vacuum system (H1:TCS-ITMY_CO2_LSRPWR_MTR_OUTPUT) is roughly stable at 0.3075 [W], where it used to deliver a really stable 0.312 [W]. I attach two zoom levels of the same 4-day trend. There's also some weird, 10-min period feature in the *minimum* of the minute-trend, where the reported power drops to 0.16 [W]. Given its periodicity, one might immediate suspect data viewer and data retrieval problems, but one can see in the un-zoomed trend that this half-power drop has been happening since the drop-out yesterday, but tracks the reported laser power even before the delivered power was increased back to nominal.
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I'm wondering if this weird behaviour is due to the RF driver - we should try to swap in the spare driver soon to check this because if the power output is really glitching low like that then it's likely to cause issues for commisioning, or possibly to fail altogether.
The temperature trend for the laser doesn't give any signs that it might have overheated.
The delivered power was recovered because I added an offset to the RS calibration so that it allows the right amount of power through. The laser itself is still outputting 42W.