jason.oberling@LIGO.ORG - posted 10:34, Friday 13 January 2017 - last comment - 14:06, Friday 13 January 2017(33224)
SR3 Oplev Laser Power Increased (WP 6433)
As noted here, the SR3 oplev began glitching at around the same time H1 experienced a large range drop. While the glitching is unlikely to be the cause of the range drop (no oplev damping on SR3), and Keita's request I have attempted to address the glitching. As soon as H1 lost lock, I increased the laser power; the voltage that monitors the laser diode current increased from 0.934 mV to 0.940 mV. This is the max for this laser, so if this does not alleviate the glitching I will try lowering the laser power. If this does not work then a laser swap will be necessary. I will leave WP 6433 open until it is known whether or not the laser power increase has alleviated the laser glitching.
After
a couple3.5 hours it seems as though the power adjustment cleared the glitching. Here is a link the SR3 summary pages; I've also attached the 2 relevant graphs to this alog. The first attachment is a time series of the oplev SUM, where the glitching is clearly visible, as is my adjustment and the following cessation of the glitching. The second attachment is a spectrogram of the SUM signal, normalized relative to the median. Here it the start and end of the glitching can be clearly seen. I will continue to monitor this over the weekend, but initially it looks like the laser power adjustment cleared the glitching for now.