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Message ID: 1301     Entry time: Tue Feb 15 00:15:28 2011
Author: Zach 
Type: Laser 
Category: GYRO 
Subject: gyro upgrade progress  

 [Alastair, Zach]

A while ago I posted an entry with an outline of what needs to be done for the gyro upgrade. Here is an updated version. Completed items are in green, items in progress in magenta, stricken items are deemed unnecessary, and comments in blue.

  1. Dismantle current setup, inventory parts and store them in an organized way
  2. Inventory space on the table and decide the basic layout for the Enhanced Gyro
    1. As we are planning to house the input/REFL optics (and the laser) in the current gyro box, we will have to choose the layout pretty carefully from the start
    2. We need to think of a way to house the final steering mirrors into the vacuum system. One will be in the input optics box, but one will not. This can contribute noise.
  3. Begin vacuum system setup
    1. Clean parts
    2. Install (Done with the exception of the mirrors themselves. The mounts should be in tomorrow.)
  4. In parallel with (3), begin input optics setup:
    1. Mount laser
    2. Install/align input polarization optics
    3. Install/align/configure EOM
      1. Do initial RFAM minimization
    4. Install CW/CCW beam separation polarizing optics
  5. Install/align CW AOM double-pass setup
    1. Maximize double-passed 1st order output beam power 
  6. Full CW/CCW beam profiling
  7. Finalize IO layout to have accurate distances for modematching
  8. Full cylindrical modematching solution for CW/CCW (we decided that cylindrical optics are not necessary, as we can obtain >99% coupling without)
    1. Find optimal solution, consider beam widths at faraday isolators
    2. Order lenses
  9. Install injection/REFL isolation optics and optoelectronics
    1. Faraday isolators
    2. Waveplates
    3. Steering mirrors
    4. Focusing lenses
    5. Attenuators
    6. Gyro RFPDs
  10. If (8.2) lead time is high, work out quick, temporary spherical solution for locking in the meantime
  11. Install cavity optics
    1. Mount into chamber
    2. Steer in input beams
    3. Align cavity eigenmode by eye
  12. RF distribution
    1. Install dedicated LO crystal
    2. Install necessary splitters, couplers and distribute to:
      1. EOM resonant circuit input
      2. CW/CCW PDH mixers
    3. Connect AOM VCO through amplifier to AOM
  13. Optimize signals
    1. Sweep laser, adjust CCW demod phase for optimal error signal
    2. Tweak cavity alignment and maximize transmission
    3. Lock CCW
    4. Sweep AOM and adjust CW demod phase for optimal error signal
    5. Adjust injection alignment to maximize transmission
    6. Iterate above as necessary
  14. Pump down
  15. Reoptimize injection alignment (CW & CCW)
  16. Build transmission demod and PLL...
  17. To be continued...

A few things have been somewhat glossed over in the above:

  1. I still have to finish making the resonant circuit for the EOM. I have borrowed the RF transformer kit from the 40m and I will hopefully have this done before we need it
  2. We haven't ordered a dedicated oscillator for the LO. I guess we will get one of the Wenzel crystals and a power amp(?). This isn't extremely time-sensitive as we can use one of the RF FGs for the moment as we have been (we need to get on this)
  3. I am working on designing the new PDH boxes for the gyro in Altium. I am guessing these won't be completely done (i.e. received, stuffed, etc.) by the time we first want to lock the eGYRO, but we can use the old boxes until they are.
  4. Alastair has finished the RFPD design, and we are pretty much ready to pull the trigger on getting the boards in. We still need to make certain that the board will be compatible with whatever box we use as it is designed. I understand that the turnaround for the PCBs is pretty short, so we can proceed with the stuffing and testing while we await the boxes. (mounts should be in this week; boxes should be in next week)
  5. Not sure about what to do with CDS. Rana is inclined to get an NDS2 server set up for the ATF, so I guess we will have to talk to John Zweizig about that. I understand that there are also plenty of other problems with the computers at the moment, though (e.g. the permissions thing). (Everything is working now as it was before. I think we decided that instead of installing NDS2---at least for now---we will just acquire some signals with multiple rates so that we can make low-frequency measurements, as well.)

 gyro_status_2_14_11.png 

 

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