J. Kissel

I've tuned up the second QUAD Bounce/Roll Damper (BRD) for H1 ITMY. As suggested yesterday after tuning the first BRD (see LHO aLOG 38645), I used the more straight-forward measurement / readout setup of hooking the output of the laser vibrometer directly to an SR785 to gather an ASD of the signal to measure the tuned frequency (instead of interfacing through the B&K software).

Here're the results for both dampers destined for H1 ITMY:
BRD S/N  007
  Blade                     Bounce (Hz)      Roll (Hz)   Freq Resolution (mHz)
  ITMY Target                9.831            13.93          10 mHz
  As Received                9.813            13.938         50 mHz
  After Tuning               9.863            13.938         20 mHz
(Target - After) / Target     0.3%             0.05%

BRD S/N  017
  Blade                     Bounce (Hz)      Roll (Hz)   Freq Resolution (mHz)
  ITMY Target                9.831            13.93          10 mHz
  As Received                10.31            14.1           31 mHz
  After Tuning               9.906            13.875         31 mHz
(Target - After) / Target     0.7%             0.4%

These have been kitted together in one bag for install on ITMY in the next two weeks.

I have left the setup as is in the back-room of the optics lab, because I'll also use this setup for measuring / tuning the HAM-ISI blade-spring Tuned Mass Dampers (TMDs). There should be enough room for any OFI characterization to work in parallel on the same optics table.