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| == Vent preparation check list == | == Preparation == |
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| * Measure all cavity lengths * Align Y-arm green beam * Reduce power to mode cleaner (appropriate level for in-air MC locking) |
We need precise measurements of the cavity lengths in order to determine where exactly we need to move the test masses. * [http://nodus.ligo.caltech.edu:8080/40m/4821 Michelson Schnupp asymmetry] * Power recycling cavity (PRC) * Signal recycling cavity (SRC) |
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| 1. Lock Y green | 1. Lock Y-arm green 1. Reduce power to mode cleaner (appropriate level for in-air MC locking) |
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Vent plan for July 2011
Overview
Major tasks for vent:
- Optimize cavity lengths: PRC, SRC, MICH, arms, etc.
- This will involve moving at least (but hopefully at most) one ITM to adjust the MICH Schnupp asymmetry. We will then need to move the ETMs and P/SRMs accordingly to set the proper arm/recycling cavity lengths.
- See wiki page on cavity lengths: [:IFO_Modeling/RC_lengths]
- Extract Y green beam from vacuum
- The green locking beam from the Y-arm is currently not making it out of the vacuum. We need to fix this by adjusting the green periscope. We will then need to adjust the X-arm green beam as well.
- Align pick-off port: POX, POY, POP
- Make sure all of these beams are cleaning making it out of the vacuum on to the PO PDs.
- Align IPANG QPD (eliminate clipping)
- Cleanly position the IPANG beam on the IPANG QPD.
Maybe:
- Adjust OSEM rotation to minimize unwanted couplings
- Install green light beam dumps
We need to have a very clear idea of exactly where all of the core/suspended optics need to be moved to.
Questions:
- What are all of the current cavity lengths, and what should they be?
- Which ITM do we need to move, and by how much?
- Where do we need to move ETMX/Y, P/SRM?
- Do we need to move the BS?
- How exactly do we move the suspended optics?
- How will we know they're in the right place?
Preparation
We need precise measurements of the cavity lengths in order to determine where exactly we need to move the test masses.
[http://nodus.ligo.caltech.edu:8080/40m/4821 Michelson Schnupp asymmetry]
- Power recycling cavity (PRC)
- Signal recycling cavity (SRC)
VENT
door removal
- BSC north
- ITMYC north
- ITMXC west
- ETMYC north
- ETMXC west
Procedure
CR:
- Lock Y-arm green
- Reduce power to mode cleaner (appropriate level for in-air MC locking)
IOOC north access:
- Adjust green periscope to extract Y green transmission
CR:
- Lock X green
IOOC north access:
- Align X green trans through green periscope
BSC north access:
- Adjust IPANG
CR:
- Misalign PRM
ITMYC north access:
- Move ITMY into position
ITMXC west access:
- Move ITMX into position
CR:
- Realign PRM
ETMYC north access:
- Move ETMY for YARM
ETMXC west access:
- Move ETMX for XARM
BSC north access:
- Move PRM for PRC
BSC north access:
- Move SRM for SRC
- Align pick-offs