• vent
• checklist

• ALWAYS check that oily Roughing Pump line is disconnected from the main volume, except when pumping down from atmospheric pressure to 500 mTorr (from which point the Turbo-pumps take over). This is to avoid the possibility of sucking oil (hydrocarbons) into the IFO main volume, which may then damage the optics if they get burnt by a high power 1064nm beam.

Pre-vent checklists

• Center all oplevs, transom QPDs (and IPPOS + IPANG if they are set up)
• Align the arm cavities for IR and align the green lasers to the arms.
• Update the SUS Dritmon values
• Reconcile all SDF differences

• Reduce input power to no more than 100mW (measured at the PSL shutter) by adjusting wave plate+PBS setup on the PSL table BEFORE the PMC. (Using the WP + PBS that already exist after the laser. Alternatively place a PBS/HWP combo after the PMC but before the HWP used to set the s-polarization for the IMC).

• Replace 10% BS before MC REFL PD with Y1 mirror and lock MC at low power.
• Close shutter of PSL-IR and green shutters at the ends

• Turn off all Oplev Servos on test masses BEFORE commencing pumpdown (to avoid trying to damp any transients during the pumpdown).

• Check that we have a recent (within 1 week) RGA scan before the vent. The cronjob should take a scan everyday anyways, but just make sure.
• Make sure the jam nuts are protecting bellows

• Check crane functionality & cleanliness

• Turn off HV into vacuum: OMC is not wired this time
• Particle count must be under 10,000 counts / cf min for 0.5 micron
• Check all metal window covers are on.
• Check 5 cylinders (24 cft size) of instrument grade air, called Alfa Gas 1 in stock.

Alignment procedure

• Align MC (center beams on MC mirrors, check with MC ASS).
• Confirm centering on input steering and mode matching optics.
  • Confirm beam is centered on TT1. Move TT1 cage if absolutely required.
  • Confirm beam is centered on MMT1. Use TT1 sliders if needed.
  • Confirm beam is centered on MMT2. Use MMT1 knobs if needed.
  • Confirm beam is centered on TT2. Use MMT2 knobs if needed.
• Place cage-mount apertures on BS and PRM cages.
• Use TT1 to center beam on PRM, TT2 to center beam on BS. This is iterative.
• Check that beam is well-centered on PR2, PR3. Should not need to touch these 2 mirrors.
• Place brass apertures on ITMY, ETMY.
• Use TT1 to center beam on ITMY, TT2 to center beam on ETMY. This is iterative.
  • Confirm beam still centered on PRM, BS.
  • Confirm beam still centered on MMT1, MMT2, TT2.
  • Confirm beam still centered on PR2, PR3.
  • Confirm beam not clipping on pickoff mirror just before PRM.
  • Iterate through aligning to ETMY, ITMY until beam is centered on input optics and Y arm optics.
• Align Y arm.
  • Use ETMY to center reflected beam onto ITMY.
  • Use ITMY to center reflected beam onto ETMY.
• Move brass apertures to ITMX, ETMX.
• Use BS to center beam on EMTX. Confirm beam is okay on ITMX (ITMX is overconstrained, so it should be okay already).
• Align X arm.
  • Use ETMX to center reflected beam on ITMX.
  • Use ITMX to center reflected beam on EMTX.
• Check to see if you have AS fringes. (May need very slight BS tweaking.) Confirm AS beam comes out of vacuum without clipping (hopefully shouldn't require any adjustment).
  • Confirm AS beam centered on SR3, SR2, SRM, output steering mirror 1. Use brass aperture for checking on SRM.
  • Confirm AS beam centered on output steering mirror 2. If absolutely necessary, adjust output steering mirror 1, however if IFO alignment is good, shouldn't need adjusting.
  • Confirm AS beam centered on output steering mirror 3 (BS table). Again, if required, use output steering mirror 2.
  • Confirm AS beam centered on output steering mirror 4. If necessary, adjust output steering mirror 3.
  • Confirm AS beam centered on output steering mirror 5 (also known as PZT3). If necessary, adjust output steering mirror 4.
  • Confirm AS beam centered on output steering mirror 6 (on OMC table, also known as PZT4). If necessary, adjust output steering mirror 5 knobs.
  • Confirm AS beam centered on output steering mirrors 7, 8. If necessary, adjust output steering mirror 6. (Output steering mirror 7 is a fixed mirror).
  • Confirm AS beam comes out of vacuum onto AS table unclipped. Should be close to the center of the first out-of-vac steering mirror. Give small offsets to suspension in pitch and yaw of ITMY and check to see that you are not close to clipping in any direction.
  • Use out of vacuum mirrors on AS table to get beam centered on AS55 RFPD and AS camera.
• Adjust PRM sliders to make PRM reflected beam retroreflecting. Check beam overlap in several places. Should see PRC flashes.
  • Near TT2.
  • Near MMT1.
  • Near TT1. (Can assume that it's also okay at MMT2).
• Check that REFL beam comes out of vacuum without clipping.
  • Check 1st mirror after Faraday.
  • Check 2nd mirror after Faraday.
  • Check that REFL is unclipped on AS table. Should be near the center of the out-of-vacuum steering mirror.
  • Check that REFL is not too close to any mirrors on OMC table.
  • Use out of vacuum mirrors on AS table to get beam centered on REFL11, REFL55, REFL camera.
• Adjust SRM sliders so that SRM beam is retroreflecting. Check in several places.
  • At SR2.
  • At SR3.
• Confirm POP backwards beam is coming out.
  • Use green laser pointer on POX/POP table, as close to camera / PD location as possible.
  • Center green beam on all (practical) out of vacuum optics.
  • Use out of vacuum optics to center beam on POP steering mirror 2 (the one closest to the viewport), and should be pretty close on POP steering mirror 1. Make sure you are always using the main beam, not a ghost.
  • Overlap main green beam with backwards IR beam (the beam between PR2 and PR3).
    • Use POP steering mirror 2 to center beam on top of IR beam just in front of PR2.
    • Use POP steering mirror 1 to center beam on top of IR beam as far toward PR3 as you can reach.
    • Iterate POP in-vac steering mirrors until green and IR beams are overlapped both in front of PR2 and as far toward PR3 as you can reach.
  • Turn off green laser pointer, align POP beam on to POP camera, POP RFPD.
  • Use IR card to slowly obscure each in-vac steering mirror while watching camera image, confirm beam is well centered.
• Confirm IPPOS beam is comes out of vacuum.
  • Confirm IPPOS beam is centered on first in-vac steering mirror. Pickoff is fixed, so this should already be true.
  • Confirm IPPOS is centered on second and third steering mirrors. If needed, adjust first steering mirror (second is a fixed mirror).
  • Confirm IPPOS is coming out of vacuum. Should be close to center of the out of vac steering mirror.
  • Use out of vacuum steering mirror on BS/PRM oplev table to center beam on IPPOS QPD.
• Confirm IPANG beam is coming out of vacuum.
  • Confirm IPANG beam is centered on first in-vac steering mirror. Pickoff is fixed, so this should already be true.
  • Confirm IPANG beam is centered on second in-vac steering mirror. If needed adjust first steering mirror's knobs.
  • Confirm IPANG beam is centered on third steering mirror (at ETMY). If needed, adjust first steering mirror's knobs.
    • Confirm beam still centered on second steering mirror.
    • If not centered on second steering mirror, may need to undo knob movement on first steering mirror, unclamp second steering mirror, and adjust it in yaw to hit third steering mirror. Reclamp second steering mirror.
  • Confirm IPANG beam is centered on last in-vac steering mirror, and comes out of vacuum. Should hit center of first out of vac steering mirror. (last in-vac mirror is fixed). Adjust third steering mirror if needed.
  • Use out of vac mirrors on ETMY table to center IPANG beam onto QPD.

  • NOTE: IPANG has a tendency to drift UP during pump down. We need to compensate for this. The drift is usually half the beam diameter up in pitch.

• Confirm POY is coming out of vacuum.
  • Use a camera, no lens, wave it around on the POY table, ensure you see beam and that beam is not clipped.
  • Fix camera, then use IR card to slowly obscure in-vac POY mirror while watching camera image, confirm beam is well centered. Repeat for obscuring from all directions.
• Confirm POX is coming out of vacuum.
  • Use a camera, no lens, wave it around on the POX table, ensure you see beam and that beam is not clipped.
  • Fix camera, then use IR card to slowly obscure in-vac POX mirror while watching camera image, confirm beam is well centered. Repeat for obscuring from all directions.
• Check all oplevs for all suspended mirrors, center oplevs on respective QPDs.
• Open Y-end green shutter, align green beam to be centered on ITMY, ETMY.
  • Check that beam is centered on up-periscope, not clipped by combining beam splitter.
  • Check that beam is not clipped on down-periscope (on IMC table).
  • Check that beam is not clipped on steering mirror on OMC table.
  • Confirm beam comes onto PSL table unclipped.
  • Close Y-end shutter.
• Open X-end green shutter, align green beam to be centered on ITMX, ETMX.
  • Check that beam is centered on up-periscope, and combining beam splitter.
  • Check that beam is not clipped on down-periscope (on IMC table).
  • Check that beam is not clipped on steering mirror on OMC table.
  • Confirm beam comes onto PSL table unclipped.
  • Close X-end shutter.
• Remove all apertures, all tools.
  • Check PRM aperture is out.
  • Check BS aperture is out.
  • Check ITMY, ETMY, ITMX, ETMX.
  • Check SRM.

Closeup checklist

• Center beam on all AS optics

• GET CAMERA IMAGES OF EVERYTHING

  • We must get images right before closing, right after closing, etc.
• Make sure REFL is clear
  • dither PRM, see motion on AP tables
• Make sure AS is clear
  • dither BS/ITM, see motion on AP tables
• Using IPANG/POS pick-off mirrors, center beams on:
  • IPPOS
  • IPANG
• Check green alignment in the arms and make sure the transmitted green reaches the PSL table.

• Check all OpLevs centered, in and out of vacuum

• Close PSL shutter & green shutters at the ends

• Check jam nuts

Post-vent checklist

• Replace Y1 mirror at MC REFL with 10% BS. Else you will BURN the PD while going back to high power.