camilla.compton@LIGO.ORG - posted 17:03, Tuesday 14 January 2025 - last comment - 15:16, Thursday 16 January 2025(82262)
CO2Y RIN at CW and PWM
Repeated 82151, with H1:IOP-OAF_L0_MADC{2,3}_TP_CH{10-13} 65kHz channels on CO2Y. WP# 12261.
Plots attached of the DC and AC out channels. These signals are straight from the PD in counts, before the filtering to undo the D1201111 pre-amp listed in 81868. PWM is at 5kHz, as can be seen in the spectrum.
Strangely when adding cursors to the laser on CW and PWM @50% signals plot, the DC channel has a factor of 30 difference but the AC channel has a factor of 5 difference. We would expect these to be the same.
Also the 95% PWM signal has lower broadband noise that the 25% and 50% PWM signals on the DC channel but higher on the AC channel.
- CW = 3880 counts, 49.1W laser power ~ RIN 1.5e-5 but limited by electronics noise.
- @50% PWM = 3500 counts, 30.0W laser power ~ RIN 5e-5
- @25% PWM = 1800 counts, 14.4W laser power
- @95% PWM = 3880 counts, 46.7W laser power
Images attached to this report
Comments related to this report
I misread the graph, for CW 100%
- CW = 3880 counts, 49.1W laser power ~ RIN 1.5e-6 but limited by electronics noise (6e-3/3880). This is higher than the 6 x 10-7 measured in 81863.