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Message ID: 14052     Entry time: Wed Jul 11 16:23:21 2018
Author: aaron 
Type: Update 
Category: OMC 
Subject: Coordination of the Output Mode-cleaner Mirror Insertion Expedition (COMMIE) 

I started this document on my own with notes as I was tracing the beam path through the output optics, as well as some notes as I started digging through the elogs. Let's just put it here instead....

  1. Beam from AS port into OMMT
  2. Reflect off OM5-PJ
    1. TO DO: check that the PZT works
    2. 40/P/F/L, 1525-45-P
  3. Pick off from OMPO
    1. TO DO: determine how much power is needed for the pick off, choose an appropriate optic (for this vent probably 50-50 is fine)
    2. The PO beam goes to OM6
  4. Reflect off MMT1???
    1. TO DO: determine if this mirror has a PZT, get it working
      1. Has a PZT?
      2. Which PZT channel on the DAQ?
      3. Is there a cable going to from the DAC to the PZT?
      4. Is the PZT functional?
      5. How many PZTs does this mirror actually have?
    2. TO DO: determine the real name of this optic, find its recent history in the elog
    3. TO DO: determine the correct telescope parameters to optimally couple into the mode cleaner given the following:
    4. TO DO: look up how the radius of curvature (RC) of the OMC has changed, and therefore what telescope parameters are necessary
  5. Focused by MMT2???
    1. TO DO: determine if this mirror has a PZT
      1. Has a PZT?
      2. Which PZT channel on the DAQ?
      3. Is there a cable going to from the DAC to the PZT?
      4. Is the PZT functional?
      5. How many PZTs does this mirror actually have?
    2. TO DO: determine the real name of this optic, find its recent history in the elog
    3. TO DO: what about this optic is tunable? It looks bulky
  6. Columnated by MMT3???
    1. TO DO: determine if this mirror has a PZT
      1. Has a PZT?
      2. Which PZT channel on the DAQ?
      3. Is there a cable going to from the DAC to the PZT?
      4. Is the PZT functional?
      5. How many PZTs does this mirror actually have?
  7. Steered by MMT4???
    1. TO DO: determine the real name of this optic
    2. TO DO: why is this optic so small? Looks different from the rest, maybe weird space constraint
  8. Steered by MMT5???
    1. TO DO: why is this optic so large compared to OMMT4?
    2. TO DO: is there a more space efficient way of steering this beam, or even some way that avoids having to steer with three distinct optics
  9. Steered by MMT6???
    1. TO DO: Can this optic be removed with some clever new beam path?
  10. Cleaned by the OMC
    1. TO DO: Where does the promptly reflected beam from OMC1 go after it exits the chamber?
    2. TO DO: check the PZTs
      1. Has a PZT?
      2. Which PZT channel on the DAQ?
      3. Is there a cable going to from the DAC to the PZT?
      4. Is the PZT functional?
      5. How many PZTs does the OMC actually have?
    3. TO DO: Determine if a new OMC configuration would be more ideal for the squeezing experiment
      1. This is a large task, not part of this immediate vent
    4. TO DO: What is done with the OMC reflection? What is done with the transmission?
    5. TO DO: Check the logs about how the OMC had been in use; should be mostly from rob ward
  11. Reflected beam goes to the next chamber
  12. Transmitted beam is split by OM7???
    1. TO DO: find the actual name of this optic
    2. TO DO: why does this have the R/T that is does?
  13. Reflected beam goes to my OMPD
    1. TO DO: figure out what this PD is used for, and whether we even need it
      1. I think this might be the camera mentioned in 40m elog 21
      2. Elog 42 says the 4 QPDs for the OMC have meds screens located under C2TPT—is this a clue for channel names?
  14. Transmitted beam is reflected to the next chamber by OM8???
    1. TO DO: determine the name of this optic
    2. TO DO: Where does this beam go? What is it used for?
  15. Beam Dumps to add
    1. Transmission through OM5? Probably don’t need…
    2. OMMT1 transmission
    3. OMMT steering mirror transmissions
    4. OMC transmissions? Probably not?
    5. OMPD transmission?
    6. OM8 transmission
    7. Green scattering off of the window where the beam goes after GR_SM5
    8. Backscatter from the OMC prompt reflection to the window
    9. Backscatter from the OMC reflection to the window
    10. Backscatter from the MC beam off the window (this beam just travels through this chamber, interacts with no optics; there is also what looks like a small blue beam on this diagram, so maybe need to dump that backscatter too)
    11. Backscatter from the PO beam from OM6 going through the chamber window
    12. Backscatter from IM1 out the window
    13. There is a small blue beam from OMMT3 that goes through this window as well, I’m not sure exactly what is is from or for, or if it is physical (there are a few of these strange blue lines, i'm probably just misreading the diagram)
  16. TESTS TO DO
    1. Characterize the PZT control
    2. Lock the OMC with a PZT dither lock
      1. Eg elog 59
    3. “Tap-tap-tappy-tap test” to find resonanes
      1. Look at combination of PDH error signal and DCPD signal???
      2. See elog 86 for results from initial OMC install—Nov 2007
    4. Check wiggling wires, etc
    5. TFs to check? Vertical TF?
    6. OMC Length check— see for eg elog 768
  17. ADDITIONAL TO DO
    1. Mode matching calculation for new radius of curvature optics—see elog 1271
      1. The current MMT is not the optimal configuration even for the old Rc (see 3077 and 3088)

 

Notes during reading elog

  • Entry 590 has a labelled picture of the optics setup with OMC
  • Mention of omcepics at elog 894
  • Some important changes happened in elog 1823
    • 1''->2'' mirror out of the vacuum--I should check whether this is still there, or if it has been moved
    • [many more changes.....]
  • There were at one time 2 cameras monitoring OMCT and R (see 4492, 4493)
  • Some OMC PZT HV supply info is at elog 4738, 4740... 
  • There are some photos of the OMC table at elog 5120, and a note about moving some optics
  • Not strictly about the OMC, but I really like Suresh's diagram 6756, I'll make something similar for the OMC electronics
    • although it is about adding the tip tilt electronics, which I think required a new flange for the OMC chamber
  • OMC stage 1 and 2 are the steering mirrors going into the OMC, and were controlled by EPICS chans (6875, 6884)
    • these PZT HV supplies lived in OMC_SOUTH (or maybe 1Y3? see elog 6893), the driver in OMC_NORTH (LIGO-D060287)
    • Photos of these supplies in 7696
  • There are pictures of the OMC and its PZTs in 7401
  • The OMC HV supply was moved to power a different set of PZTs (see 7603)
  • Talk of replacing the PZTs with picomotors or tip/tilts in 7684
  • More pictures of the OMC table before the OMC was 'removed' are here (8114) and in 12563/12571 Gautam links to a Picassa album with pictures from just before the beam was diverted
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