{Paco, Yehonathan}

Today we suspended LO2 (E1800089) which Anchal has loaded into the thick optic adapter. Attachments 1,2 show the height and roll balance adjustments.

I realigned the opLev setup and balanced the suspended mass. We figured that if we use 2 counterweights we will be 1 short. We decided to use 1 mass at the back of the adapter. This has the additional advantage that the Viton tip on lower back EQ stop can touch it and act normally. The optic was successfully balanced in this way. Attachment 3 shows the motion spectra on the QPD. There are major peaks at 712 mHz, 854 mHz, 876 mHz, and 996 mHz. As expected using only 1 counterweight raised the center of mass and lowered the pitch resonance frequency. The optic was locked keeping the alignment fixed on the center of the QPD, OSEMs were inserted and the SOS tower was engraved.

We should apply some glue to the counterweight to prevent it from spinning on the setscrew.