• Optics_Cleaning

Cleaning of the suspended test mass (Dec 2009)

Motivation

The round trip loss in the 40m cavity is estimated to be around 160ppm. We are going to confirm wether this comes from the hydrocarbon contamination and wiping of the mirror by acetone and isopropy may result in improvement of the optical loss, or not.

In addition we cna evaluate the use of those solvents. If we observe the degradation of the loss or the finesse, we will forbid them.

Measurements before the vent

- Visibility measurement

Most recent arm visibility measurement has been done on Oct 07, 2009. [http://nodus.ligo.caltech.edu:8080/40m/2070 corresponding elog entry]

Measured arm reflectivity R_cav:
X arm: 0.875 +/- 0.005
Y arm: 0.869 +/- 0.006

- Cavity pole measurement

Most recent arm visibility measurement has been done on Nov 10, 2009. [http://nodus.ligo.caltech.edu:8080/40m/2226 corresponding elog entry]

Measured arm cavity pole frequency f_pole [Hz]:
X arm: 1720 +/- 70
Y arm: 1650 +/- 70

Overview of the plan

• We plan for the vent from 7th Dec to 11th Dec in 2009.

• Preparation

  • wiping preparation
  • wiping practice
  • aux beam as a reference....align to overlap in vacuum
  • Input PZT (strain gauge) /HV off/OMC PZT HV
    • update snap shots: sus, strain gauges,IOO, OMC....etc (OMC has no strain gauges)
    • recenter: IP-ANG-POS, oplevs..... at full lock
  • test drive crane drives
  • clean clean-tools again
  • keep eyes on particle counter: abort over 10,000
  • cut some viton tips for spare earthquake stop screws
  • look that we have good RGA scan

• Monday:

  • Vent / Open ETMX if possible
  • Take pictures before touching
  • Record positions of the mirrors (OSEMs/OPLEVs)

• Tuesday:

  • ETMX wipe
  • ETMY wipe

• ~ Wednessday:

  • IPANG beam
  • ITMX position (pushing screws)
  • ITMX BB leveling
  • measure the distance of the breadboards
  • check of the optics in the chambers
  • ITMY wipe
  • ITMX wipe

• Thursday: - Evacuation

• Friday:

Detailed plan

• ~Friday, 4 Dec:

  • Wiping preparation

    • Chemicals: small bottles (like 250ml) / 3 bottles each (no matter how the size is), Acetone Spectral Grade, dehydrated (if possible), Isopropyl alcohol Spectral Grade, dehydrated (if possible)

    • glass sylinges with metal needles, 50ul, at least three sets
    • mirror wiping paper, usual lens paper from Kodak or whatever
    • tools (well cleaned)
    • clamps to mark the position of ITMX: 3pcs
    • halogen light or whatever: light during the work

• Friday, 4 Dec:

  • Practice cutting viton, so we can get the correct sizes if we need to replace stops. (Jenne)
  • Recenter all of our pointing PDs (oplevs and IP_POS, IP_ANG). (DONE 10pm Friday)
  • Update snapshots of all MEDM screens that have alignment information. (DONE 10pm Friday)
  • Move extraneous equipment around chamber doors: Make sure we have clear access (esp. seismometers need moving) (DONE 5pm Friday)

• Monday:

  • Before venting, check that all the recentering done on Friday is still good. If not, redo.
  • Vent
  • During vent, practice drag wiping a spare random optic (maybe a 2" CVI optic?)
  • Open ETMX
  • Take photos of ETMX before touching
  • Close up ETMX with light doors for the night

• Tuesday:

• Wednesday:

• Thursday:

• Friday: