Reduced the baffle PD gain in ETMX PD 1 to 0dB from 20dB (H1:AOS-ETMX_BAFFLEPD_1_GAIN), since it was pegged at 10V.
ETMX baffle PDs 2, 3 and 4 are ok and gain at 20dB.
ETMY baffled PD 1 is close to saturation and gain is 20dB.
ETMY baffle PDs 2 and 3 have a gain of 0dB and show very small signals. Could be increased to 20dB.
ETMY baffle PD 4 saturates at the begining of a lock. Gain could be decreased to 0dB.
ITMX baffle PD 1 gain at 0dB, 20dB for all others, signal ok.
The ITMY baffle PD 3 readout seems broken since at least January 2022; maybe related to this upgrade.
All gains at 20dB, signals for all but PD 3 seem ok.
The attached trend plot shows all baffled PDs at 75W and 60W input. The transition happens near -5d in the plot. The power reduction is as high as a factor of 2 but typically much less.
Daniel has also taken it as an action item to work with an operator to ensure that the gain changes are handled nicely by the baffle PD script, since we use PDs 1 and 4 on each test mass to help us align the green beam if we cannot see flashes. Daniel's suggestion is to have the script increase the gain values to what they had been, and then after the script completes, return them to the lower values that they have now. This should allow the PDs to be useful for both the pre-initial alignment, as well as be useful when in full lock.
Changed and restored the baffled PD gain in the baffleAlign.py script (function alignToBafflePD). Needs testing.
Script tested