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Manasa has done some work to get the Xgreen aligned, so I'll switch to trying to find that beatnote for now.
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[Jenne, Manasa]
Aligned X-arm green in TEM00.
It was difficult to get the X-arm to lock in TEM00 earlier. Even when it locked, it was just a TEM00 flash. The green was mainly bad in pitch.
I started aligning with the arms flashing in IR and it was still not possible to lock. The second trial was with the arms locked in IR; I lost the green lock when the arms were aligned for IR. I aligned by overlapping the ingoing green with the reflected green visible on the steering mirror. This got the green to lock in TEM00; but still it would only stay that way for 30 sec. Jenne pointed me to Yuta's suggestion of increasing the green refl PD gain. Once I increased the PD gain, the mode stabilized.
I went ahead and centered ALS TRX on the PD and GTRX camera (on the PSL table). ALS_TRX reads 2000+ counts.
EDIT by Jenne: This corresponds to a power of 550uW on the PSL table, measured before the first out-of-vac steering mirror. |