A current draft document containing schematic layouts of 4 options for NDRCs plus radii of curvatures and beam parameters for the NDPRC can me found here: NDRC_layout (21/02/2009 Andreas).

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The rest of the page refers to the first stage of this work which led to the preliminary design

Name convention for the  recycling mirrors:

• PRM1: This is the main Power Recycling mirror and this is the first core optics element a beam coming from the injection bench sees and is transmitted through.
• PRM2: This is a telescope mirror, that reflects the beam coming from PRM1 towards PRM3.
• PRM3: This is the second PR telescope mirror, placed between PRM2 and the main beam splitter.
• SRM3: This is the first telescope mirror (seen from the beam splitter) of the Signal-Recycling telescope. It is positioned between BS and SRM2.
• SRM2: This is the second SR telescope mirror, placed between SRM3 and SRM1.
• SRM1: This is the main Signal-Recycling mirror and the last core optics element a beam leaving the interferometer encounters. 
  

Potential positions of the 6 recycling mirrors (very preliminary):

• PRM1: north end of injection bench
• PRM2: center of PR tower
• PRM3: north end of injection bench
• SRM1: west end of detection bench
• SRM2: center of SR tower
• SRM3: west end of detection bench

Resulting distances between the individual recycling mirrors

• BS - PRM3: about 10.5 m
• PRM3 - PRM2: about 4.5m
• PRM2 - PRM1: about 4.5m
• BS - SRM3: about 10.5 m
• SRM3 - SRM2: about 4.5 m
• SRM2 - SRM1: about 4.5 m
• BS - IMX: about 6.25 m (will probably shifted to also be 5.5 m resulting in a Schnupp symmetry of only a few cm).
  
• BS - IMY: about 5.5 m

A first design iteration: Adapting the ALIGO design

As a first and very preliminary design of the stable recycling cavities for Advanced Virgo, we try to rescale the ALIGO design to fit into the Advanced Virgo system.
A brief summary of the ALIGO design parameter can be found on this page.

The Advacned LIGO design of the PRC has been succesfully adapted to the Advanced Virgo
layout, see Virgo note VIR-081A-08.

The main parameters of this first draft layout can be summarized in the following table:

RCimxAR=10.5;
RCprm3=30;
RCprm2=-1.8492;
RCprm1=2.1178;

arm cavity mode in vacuum q =1400 + i 275.838
arm cavity mode in substrate q =1427.97 + i 194.083
   |RCimxAR i1|RCimxAR o2|        BS|  RCprm3 1|  RCprm3 2|  RCprm2 1|  RCprm2 2|  RCprm1 1|  RCprm1 2|
w: |        50|        50|      38.5|      16.5|      16.5|      2.17|      2.17|      1.77|      1.77|
w0:|      6.74|     0.162|     0.162|     0.162|     0.106|     0.106|     0.395|     0.395|     0.395|
z: |  1.43e+03|     -23.9|     -18.4|     -7.91|     -5.18|    -0.679|     -2.49|      2.01|     -2.01|
Rc:|  1.45e+03|     -23.9|     -18.4|     -7.91|     -5.18|     -0.68|     -2.57|      2.12|     -2.12|
roundtrip Gouy phase Psi=5.56514 rad
single trip Gouy phase Psi=159.43 deg