Ushiba, Akutsu

In 24557, it is hard to bring reasonable theories why PRMI 3F lock would cause beam jitter. To break down this difficult problem, we checked if the same behavior would be observered even in the PRMI with ETMs misaligned (simply putting, no arms), or in other words, during the initial alignment.

Fig. 1 is the spectrogram of K1:IMC-IMMT1_TRANS_QPDA2_DC_PIT_OUT_DQ, while Fig. 2 is a time series of K1:GRD-INITIAL_ALIGNMENT_STATE_N. Taken from Mar 26 2023 00:56:30 UTC to Mar 26 2023 01:01:30 UTC. As shown in these figures, although the Guardian state evolved, IMMT1 trans QPD did not show any significant changes in the spectrogram.

So what do these facts (this post and 24557) mean? What is the path of the noise? How arm signals affect this? And what is the actuator of this beam jitter even in 100 Hz?