Yao-Chin and Yuhang

When IRMC locking, we monitored yaw & pitch of LO light jittering by position sensitive detector(PSD) as shown in fig 1. PSD was put before alignment mode cavity(AMC). We also measured yaw & pitch of PSD dark noise.

In addition, we sent 200mV Vpp of random noise to IR phase shifter(IRPS) and measured again yaw & pitch of LO light jittering as shown in fig 2. Magnitude value increased more obviously above 60Hz than without random noise situation.

When BAB light sent to filter cavity, we monitored yaw & pitch of reflect light by PSD as shown in fig 3. Because suspension mirror jittering, The jittering magnitude of low frequency range (<200Hz for yaw, <500Hz for pitch) is huge.