Several oplev maintenance items were completed today.

Swap ETMx OpLev Laser

I swapped the ETMx oplev laser as the old laser was glitching and there was no more adjustment room with the laser power to follow the glitch-free zone.  The new laser SN is 130-1, old laser SN was 106-1.  The output power of laser SN 130-1 was set to the same point used in the Pcal lab (using the Current Mon port on the back of the laser): 0.793 V.  I will test laser SN 106-1 in the Pcal lab in the LSB to see if it is still useful or if a return for refurbishment is necessary.

Re-center ETMx, ITMx, and SR3 OpLevs

After the May vent the alignment of these 3 optics changed slightly, requiring re-centering of their oplevs.  This has now been completed.

Power Adjustment for ITMy and ETMy OpLevs

Both of these oplev lasers were showing signs of very slight mode-hop glitches, so I adjusted the output power of both lasers to return to a glitch-free operating power.  I used the Current Mon port on the back of the lasers to monitor the power increase (the port outputs a voltage).  The adjustments were:

• ITMy
  • Old: 0.757 V
  • New: 0.765 V
• ETMy
  • Old: 0.865 V
  • New: 0.875 V

All of the effected lasers (ETMx, ITMy, ETMy) will need a few hours to return to thermal equilibrium, therefore I will assess whether or not they are still glitching and require further adjustment later this afternoon.  This completes WP 7042.  Should further adjutments to these lasers be required, I will open a new work permit.