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| This page describes the big topics in the Upgrade of the 40m interferometer from Mk III to Mk IV. | This is a collection of links relating to the 2008 40m Upgrade. |
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| The main point is to make it more like the AdvLIGO interferometer. There are not too many details on this page so as to not reduce clarity. | [[/Overview]] |
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| People should feel free to add comments - | == Upgrade document == * [[TAC Meeting-Apr 08]] ([http://lhocds.ligo-wa.caltech.edu:8000/40m/TAC_Meeting-Apr_08?action=AttachFile&do=get&target=Upgrade08.pdf Upgrade08.pdf], or [https://40m.ligo.caltech.edu/svn/40m/docs/upgrade08/ SVN repository]) * [http://lhocds.ligo-wa.caltech.edu:8000/advligo/ISC_Modeling_Software/CVSinstructions?highlight=%28CVS%29 "MIT CVS repository instructions for accessing AdvLIGO modeling"] |
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| == Arm Cavity Finesse == We will change the transmission of the ITMs from 0.5% to 1.4% to match the new AdvLIGO design. |
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| We will also replace the MOS (with 1.25 kg masses) with SOSs. This is to increase the effect of radiation pressure. | == Coatings and Optics == This is a work in progress area for what optic and coatings we need. |
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| 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. |
|| Parameter || ITMs || ETMs || PRM || SRM || FM (4x) || || HR Transmission 1064 nm || 0.014|| 10 ppm || || || <0.01 || || HR Transmission 532 nm || < 1000 ppm|| 0.10 || || || || || AR Reflection 1064 nm || 1000 ppm|| < 100 ppm || || || <0.01 || || AR Reflection 532 nm || <0.01|| < 1000 ppm || || || || || ROC || inf|| 40 m? || || || inf|| || Wedge angle || 1 deg || 1 deg || || || || |
Upgrade of the 40m
This is a collection of links relating to the 2008 40m Upgrade.
Upgrade document
TAC Meeting-Apr 08 ([http://lhocds.ligo-wa.caltech.edu:8000/40m/TAC_Meeting-Apr_08?action=AttachFile&do=get&target=Upgrade08.pdf Upgrade08.pdf], or [https://40m.ligo.caltech.edu/svn/40m/docs/upgrade08/ SVN repository])
[http://lhocds.ligo-wa.caltech.edu:8000/advligo/ISC_Modeling_Software/CVSinstructions?highlight=%28CVS%29 "MIT CVS repository instructions for accessing AdvLIGO modeling"]
Coatings and Optics
This is a work in progress area for what optic and coatings we need.
Parameter |
ITMs |
ETMs |
PRM |
SRM |
FM (4x) |
HR Transmission 1064 nm |
0.014 |
10 ppm |
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<0.01 |
HR Transmission 532 nm |
< 1000 ppm |
0.10 |
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AR Reflection 1064 nm |
1000 ppm |
< 100 ppm |
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<0.01 |
AR Reflection 532 nm |
<0.01 |
< 1000 ppm |
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ROC |
inf |
40 m? |
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|
inf |
Wedge angle |
1 deg |
1 deg |
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