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Entry  Mon May 2 17:11:55 2016, rana, Update, COC, RC folding mirrors 
    Reply  Wed May 18 01:10:22 2016, gautam, Update, COC, Finesse modelling arms.pdfPRC.pdfSRC.pdfFinesse_model.zip
       Reply  Tue May 24 22:49:02 2016, gautam, Update, COC, Finesse modelling - mode overlap scans 9x
          Reply  Tue May 24 23:17:37 2016, ericq, Update, COC, Finesse modelling - mode overlap scans 
             Reply  Thu Jun 16 15:57:46 2016, gautam, Update, COC, Contrast as a function of RoC of ETMX contrastDefect.pdffinesseCode.zip
                Reply  Thu Jun 16 18:42:12 2016, rana, Update, COC, Contrast as a function of RoC of ETMX 
                   Reply  Thu Jun 16 23:02:57 2016, gautam, Update, COC, Contrast as a function of RoC of ETMX contrastDefect.pdf
                      Reply  Mon Jun 20 01:38:04 2016, rana, Update, COC, Contrast as a function of RoC of ETMX 
                         Reply  Mon Jun 20 18:07:15 2016, gautam, Update, COC, Contrast as a function of RoC of ETMX contrastDefectComparison.pdf
             Reply  Tue Jun 28 16:06:09 2016, gautam, Update, COC, RC folding mirrors - further checks C1_HOMcurves_Y.pdfC1_HOMcurves_DR.pdf
                Reply  Thu Jun 30 16:21:32 2016, gautam, Update, COC, Sideband HOMs resonating in arms image.jpegC1_HOMcurves_Y.pdfC1_HOMcurves_X.pdf
                Reply  Sat Aug 13 18:25:22 2016, gautam, Update, COC, RC folding mirrors - Numerical review PRX_consolidated.pdfSRX_consolidated.pdfGouy_PRC.pdfGouy_SRC.pdf
                   Reply  Tue Aug 16 11:51:43 2016, gautam, Update, COC, RC folding mirrors - Numerical review PRC_consolidated.pdfSRC_consolidated.pdfGouyPRC.pdfGouySRC.pdf
                      Reply  Tue Aug 16 16:38:00 2016, gautam, Update, COC, RC folding mirrors - Numerical review PRC_consolidated.pdfSRC_consolidated.pdfGouyPRC.pdfGouySRC.pdf
                         Reply  Wed Aug 17 14:37:36 2016, gautam, Update, COC, RC folding mirrors - Numerical review PRG.pdf
                            Reply  Wed Aug 17 16:28:46 2016, Koji, Update, COC, RC folding mirrors - Numerical review 
                            Reply  Mon Nov 21 15:34:24 2016, gautam, Update, COC, RC folding mirrors - updated specs Recycling_Mirrors_Specs_Nov2016.pdf
                               Reply  Thu Feb 23 10:59:53 2017, gautam, Update, COC, RC folding mirrors - coating optimization PR3_R_170222_2006.pdfPR3_123_TOnoise_170222_2203.pdfPR3_123_Layers_170222_2203.pdfPR3AR_R_170222_2258.pdfPR3AR_123_Layers_170222_2258.pdf
                                  Reply  Tue Mar 14 10:56:33 2017, gautam, Update, COC, RC folding mirrors - coating optimization PR3_R_170313_1701.pdfPR3AR_123_Layers_170313_1701.pdfPR3AR_R_170313_1752.pdfPR3AR_123_Layers_170313_1752.pdf
                                     Reply  Mon Apr 10 15:37:11 2017, gautam, Update, COC, RC folding mirrors - v3 of specs uploaded  8x
Message ID: 12887     Entry time: Tue Mar 14 10:56:33 2017     In reply to: 12847     Reply to this: 12936
Author: gautam 
Type: Update 
Category: COC 
Subject: RC folding mirrors - coating optimization 

Rana suggested including some additional terms to the cost function to penalize high sensitivity to deviations in the layer thickness (L). So the list of terms contributing to the cost function now reads:

  1. Thermal noise - we use the proxy function from E0900068-v3 to do this
  2. Deviation from target T @1064nm, p-pol
  3. Deviation from target T @532nm, p and s-pol
  4. HR Surface field
  5. The ratio \frac{d\mathcal{T}/\mathcal{T}}{dL/L} with dL/L = 1%, evaluated at 1064nm p-pol and 532nm p and s-pol (only the latter two for the AR side)

I did not include other sensitivity terms, like sensitivity to the refractive index values for the low and high index materials (which are just taken from GWINC).

There is still some arbitrariness in how I chose to weight the relative contributions to the cost function, but after some playing around, I think I have a solution that I think will work. Here are the spectral reflectivity and layer thickness plots for the HR and AR sides respectively. 

HR side: for a 1% increase in the thickness of all layers, the transmission changes by 5% @ 1064nm p-pol and 0.5% @ 532nm s and p-pol

  

AR sidefor a 1% change in the thickness of all layers, the transmission changes by <0.5% @ 532nm s and p-pol

  (substrate to the right of layer 38)

I've also checked that we need 19 layer pairs to meet the spec requirements, running the code with fewer layer pairs leads to (in particular) large deviations from the target value of 50ppm @ 1064nm p-pol.

Do these look reasonable? 

 

Attachment 1: PR3_R_170313_1701.pdf  69 kB  | Hide | Hide all | Show all
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