R&D (FilterCavity)
MarcEisenmann - 12:14, Thursday 09 February 2023 (3167)
PLL and IRMC realignment

[Marc, Nishino, Shalika]

Today's goal was initially to recover the 2 PLLs alignment.

However, we found out that one of the newly installed steering mirror to recover the beam tilt because of the wedge of the new EOM was quite miscentered.

We realigned this mirror but then also had to realign several optics afterwards..

This meant that both PLL and IRMC alignment got destroyed.

For the PLL part, we tried to recover the coupling of Main Laser to the fiber as in elog 1200.

Luckily, we still had transmitted beam after the single mode fiber.

After some tweaking we got:

ML-AUX1: 3.7 mW → 430 uW, coupling: 0.43*2/3.7 = 23.2% (before 33%)
ML-AUX2: 4.9 mW → 700uW, coupling: 0.7*2/4.9 = 28.2% (before 31%)
 
Next step will be to tune the incident polarization with our installed HWP.
 
For the IRMC realignment we could not see any transmission or flashes.
Realignment is on-going.