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Purpose of the upgrade

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To demonstrate AdvLIGO interferometer technologies

►Prototyping of AdvLIGO LSC

• Lock acquisition

  • "Prove AdvLIGO LSC actually works"

  • [=> Link to 40m lock acq][=> Link to AdvLIGO LSC scheme]

• Green laser locking [=> Link to 40m ALS][=> Link to AdvLIGO ALS]

  • "Realize lock of the arms independently from the main beam"

  • "Achieve semi-deterministic lock & smooth handing off"

• Noise mechanisms / DC readout

  • "Discover and/or confirm by a model RSE specific noise couplings"

►Tuned / Detuned RSE comparison

• "Clarify advantage and disadv. of the tuned/detuned configuration"
• "Demonstrate smooth transition"

►RGC based digital control system

• "Demonstrate complicated LSC code on the connected multiple systems"
• "Establish rapid prototyping methods with simulated plants on the processors"

• [=> Link to 40m CDS][=> Link to AdvLIGO CDS]

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To do anything useful to make the AdvLIGO easier / faster

►DC&Dither technologies

• Offset lock and handoffs
• AF WFS technique
  • "Develop and characterize various new useful techniques"

►Interferometer Diagnosis

• Cavity characterization using aux. laser injection
  • "Provide a method of precise in-situ characterization of the interferometer"

►Development / test bench of advanced technologies

• GigE CCD WFS technique

• Adaptive noise cancellation [=> Link to 40m ASS]

  • "Demonstrate how it works"
  • "Understand and improve its limitations"

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Major things to be upgraded

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►Interferometer design

• AdvLIGO like optical configuration / sensing scheme
  • Arm finesse of about 450

  • 2 Phase modulations (11MHz & 55MHz), no Mach Zehndar

  • Longer PRC/SRC => Use of Folding mirror

  • PR gain decided for carrier, SR gain decided by sensitivity

  • Small asymmetry, extraction of f2 by a undercoupled SEC => good through put of f2 to the dark port

  • Use of third harmonic demodulation scheme
  • Links to [Optical Configuration][Power Budget][Optical Layout][PRC/SRC design][Sensing scheme][Lock Acquisition scheme]
• Smaller ITMs/ETMs for lower the optical spring frequencies
• Tuned or detuned?
  • Tuned / offset detuning What should be compared?

►Green laser locking

• Arm length stabilization using auxiliary 532nm lasers at the end of each arm.
  • Dichroic coating (1064nm/532nm) for ITMs and ETMs
  • Link to [Green locking]

►CDS (Control and Data System)

• AdvLIGO style digital control system utilizing Matlab/Simulink (Realtime Code Generator)
• Realtime code development with "virtual interferometer"
• First test for Realtime code development with "virtual interferometer"
• Links to [CDS upgrade]

►Mechanics

• Use of Tip-Tilt suspenions which is similar to one for ELIGO and AdvLIGO
• Use of Small Optics Suspensions for ITMs/ETMs.
• Links to [Suspension upgrade]

►Electronics

• Upgrade of the RF detection systems
  • PDs/demodulators/RF distributors
• Use of a multiple resonant EOM
• Links to [Electronics upgrade]

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