Arm Cavity Finesse
We will change the transmission of the ITMs from 0.5% to 1.4% to match the new AdvLIGO design.
We will also replace the MOS (with 1.25 kg masses) with SOSs. This is to increase the effect of radiation pressure.
We will not fine-tune the coatings of the ITMs for cool dichroic properties unless some coating place gives us a <4 month lead time.
Modulation Frequencies
We will change the modulation frequencies from f1=33 MHz and f2 = 166 MHz to f1 = 9 MHz and f2 = 45 MHz. We will increase the length of the MC to accomodate this.
Recycling Cavities
We will increase the length of the RCs to handle the lower modulation frequency. This will require 2 tip/tilt mirrors per cavity. These will be imperial, eddy current damped versions of the ANU tip/tilt mirrors.
Should we get new PR and SR or use what we have? (curvature, reflectivity). Maybe we should match the AdvLIGO Gouy phases.
We will make the tip/tilts so that we can have a POP signal. We also keep POX & POY.
Mach Zender
We will not use a Mach Zender. We will use 2-3 EOMs in series or a UF Trimod if it shows up.
Control System Computers
We will have a big multi-core box to run all of the front ends. It will have fast fiber links to remote ADC/DACs.
Multi-wavelength Locking
Make wedges and coatings to accomodate multi-color locking if the lead time is reasonable. The beam from the end should not see the corner.
Optical Levers
Make a fiber based OL delivery scheme. Try to also make 40m long OLs by putting turning mirrors into the vacuum system.
Analog Electronics
Suspensions
No change of the suspension analog electronics. We will have interface cards/connectors to go from new style ADC/DACs into the old analog electronics.
LSC
New RFPDs for the 9 & 45 MHz as well as 3*f1 (27 MHz). Maybe DD as well.
Cameras
We'll have GigE cameras and an all GigE backbone for all CDS connections.