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YuhangZhao - 00:56, Saturday 14 December 2019 (1945)Get code to link to this report
Alignment of homodyne

Matteo and Yuhang

Today we tried to align homodyne to have flat shot noise until 10Hz. However, no matter what we tried(including aligning homodyne's BS, two lenses in front of homodyne, and adjusting the flipping mirror ) we always have a strong peak at 14.25Hz and its harmonics. We still don't understand why we have these peaks.

We checked the resonance of the bench and it is not the reason.

We checked we didn't send any modulation to IR phase shifter.

We checked we didn't send perturbation to IRMC. Also, IRMC error signal/reflection is very clean at low frequency.

We checked the main laser doesn't have strange behavior. We checked the noise eater. We checked PLL.

We will continue the investigation next week.

Comments related to this report
YuhangZhao - 13:44, Sunday 15 December 2019 (1946)

According to elog1868, there is a peak of bench appears at 14.2Hz when we excite EW direction.