[Ushiba, Hirose, Sugioka]

Abstract:

We aligned and locked PRX with 1F and 3F, and performed calibration and phasing for them. Detailed changes in Guardian will be posted by Hirose-san later.

Details:

We initialy attempted to align PRMI, but because locking PRMI was unsuccessful, we shifted our approach to achieve a PRX lock first.

To begin, we measured the dark offsets at POP_PDA1_RF17, POP_PDA1_RF45, REFL_PDA2_RF51, and REFL_PDA2_RF135, and subtracted them by applying the measured values to their respective PD_OFFSET channels. We then adjusted the alignment of PRM while monitoring the REFL camera images and the POP_PDA2_RF90 signals. Following this, we performed a rough phasing for POP_PDA1_RF45 while observing the I/Q time-series signals.

We then requested the PRX_3F_LOCKED Guardian state. By inspecting the control and error signals, we found that the control gain was insufficient. To resolve this, we increased K1:LSC-PRCL1_GAIN from 0.15 to 1.0 and updated the lock threshold signal in the PRX_3F_LOCKED state from POP_PDA2 (DC) to POP_PDA2_RF90. With these adjustments, we successfully achieved the PRX_3F_LOCKED state.

After locking, the signal in the K1:LSC-PRCL2_OUT channel was calibrated to nanometer units using the cali_PRC filter, and OL gain was tuned to mach the reference(Figure1.1).We also fine-tuned the phasing by applying excitation to K1:LSC-PRCL1_EXC at 100.125 Hz(Figure.2). 

Following the same procedure, we subsequently locked PRX 1F and completed its calibration and phasing(Figure.3,4).