This is a follow-up study for 29524, 29556,
Synopsys- With the current CO2 and ring heater settings, the readout gain for laser frequency with REFL45I does not flip the sign any more during and after the power up.
Some details- Here is a screenshot showing the sensing gain for laser frequency at REFL_A_9I and REFL_A_45I from the last night. The sensing gain were monitored by the mod/demod technique at 900 Hz which is the same as what Stefan did in the past (29524, 29556).
- (blue) REFL_A_9I using DEMOD_2 [arbitrary unit]
- (green) REFL_A_45I using DEMOD_3 [arbitrary unit]
- (brown) power recycling gain [W/W]
- (cyan) IMC input power [W]
Very similarly to the past observations, REFL_9I maintains a steady gain throughout the measurement. REFL_45I was also stable. Its sensing gain changed by a factor of two from the beginning of the 50 W operation to the end of the measurement (for about 35 minutes). As opposed to the previous observations, REFL_45I did not experience a large deviation of more than factor of two or sign flip. This is consistent with our experience in the sense that the interferometric loops can hold the interferometer locked without significant changes during and after the power-up.
Some notes on the thermal settings that we used in this measurement:
- CO2X 500 mW --> 240 mW (as we power up)
- CO2Y 1000 mW --> 0 (as we power up)
- RH [ITMX, ITMY] = [0.5 W, 2.5 W]
- RH [ETMX, ETMY] = [1.5 W, 0 W]