Travis S., Jeffrey G.

On Friday, the diagonalization of the OSEMs on the M1 stage of the FMY was completed for the Yaw DoF.  For Yaw, the drive was a sine wave at 1.4Hz with a 200ct amplitude.  The first attached plot shows the "F1", "LF", "RT", and "SD" OSEMs are isolated nicely at ~30dB from the two Vertical DoF contributing OSEMS - "F2" and "F3".  There was a bit of tweaking involved as far as the amplitude of the drive to see a nice transfer function, but after adjusting the alignment of the OSEMs, an amplitude of 200cts was enough drive to see the isolation.

For the Vertical DoF - "LF" and "RT" contributions - the isolation from the other OSEMs was not as clean. The subsequent two attached plots labelled "*_vert_*" show the first drive at 1.1Hz with 2500cts and the second drive with 3000cts.

For the 2500ct amplitude transfer function, the other ("F2","F3", "SD") OSEMs were isolated better at ~20dB, but not quite down to the desired ~30dB. "F1" only displayed a 10-15dB isolation.  The "F1" OSEM response was noticed to be coupled undesirably too much to the Vertical drive.  The filtered signal from "F1" (after the OSEM "input filters" implemented in the medms via foton) had some unexpected noise contribution.  There was some investigations into the signal chain/electronics rack to pinpoint the cause of this added signal noise.  No initial electronics issue was found, so the investigation continued into the software implementation.

For the 3000ct amplitude transfer function, the isolation for "F3" and "F2" was much better at ~30dB.  The "SD" isolation was at about 24-26dB.  "F1" still had the same coupling issues and did not improve isolation from the increased drive amplitude. The "F1" OSEM noise was noticed at the end of the day to settle down when the input filter was turned off on the medm.  Further information to come.

The flags were adjusted with tweezers to align them parallel to the LED light and PDs as well as the OSEM housing themselves.  These adjustments were done in between measurements to improve the isolation.

Apologies for the sideways plots in the pdfs - it was DTT.