Stefan and Kiwamu

This is an alog which I was going to post yesterday but hesitated to post as Stefan already posted his one (see alog 8791).

We are still in the process of recovering the IMC locking. The alignment got back to an OK state where we can try locking the IMC, but currently it is prevented by the corner Twincat as it is unable to control the common mode board for some reason.

Here is what we did today:

• The Apollo people moved the IOT2L table in place.
• Filiberto, Stefan and I re-installed the exterior cables.
• We installed two light pipes between the HAM2 chamber and table enclosure.
• LVEA was transitioned to laser hazard to allow for a beam going to the IMC and IOT2L table.
  • The beam was actually already hitting the length PD and wavefront sensors.
  • However the beam was off from the center of most of the optics on the table.
• We did a fine tuning of the table location by physically move the entire table by approximately 3/4".
  • In this way, we centered the IMC REFL beam on the top periscope mirror on IOT2L.
• We tweaked the PSL PZT to get a decent interference in the REFL beam.
  • The misalignment seemed mostly in pitch.
• We realigned the optics in the IMC-REFL path on IOT2L.
  • The beam is now well-centered on every optic and every PD.
• We looked at the PDH signal and found that the I-Q angle had rotated again.
  • Right now it seems that the I-output is optimized while the Q-output had been used for locking.
  • So, obviously the modulation phase rotated by 90 deg again.
  • The signal amplitude also look too small. It is about 80 mVp-p at the I-output while it used to be 1.2-ish V.
• We switched the cables so that the I-output goes to the input of the common mode board.
• Then we found that the Beckoff is not running properly.

The attached is the initial alignment of the day where we could get a decent flash.