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Entry  Thu Mar 4 17:04:52 2021, Paco, General, Design specs, Silicon TM dichroic coatings for phase I ETM_coating_candidates.pdfITM_coating_candidates.pdf
    Reply  Wed Mar 17 19:51:42 2021, Paco, General, Design specs, Silicon TM dichroic coatings for phase I ETM_R_210317_1927.pdfETM_Layers_210317_1927.pdfETM_nominal_cornerPlt.pdf
       Reply  Wed Mar 17 21:24:27 2021, gautam, General, Design specs, Silicon TM dichroic coatings for phase I 
          Reply  Wed Mar 24 17:36:46 2021, Paco, General, Design specs, Least common multiple stacks and varL cost ETM_Layers_210323_0925.pdf
             Reply  Fri Apr 2 19:59:53 2021, Paco, General, Design specs, Differential evolution strategies diffevostrategies.pdf
                Reply  Fri Jun 4 11:09:27 2021, Paco, General, Design specs, HR coating tolerance analysis 
          Reply  Wed Mar 24 17:42:50 2021, Paco, General, Design specs, Silicon TM dichroic coatings for phase I 
Message ID: 8     Entry time: Wed Mar 24 17:36:46 2021     In reply to: 7     Reply to this: 10
Author: Paco 
Type: General 
Category: Design specs 
Subject: Least common multiple stacks and varL cost 

Update on ETM/ITM coating design;

- Following what seemed like a good, intuitive suggestion from Anchal, I implemented a parameter called Ncopies, which takes a stack of m-bilayers and copies it a few times. The idea here was to have stacks where m is the least common multiple of the wavelength fractional relation e.g. m(2/3) = 6 so as to regain some of the coherent scattering in a stack. Unfortunately, this didn't work as planned for m=6, 3, and 2.

- While the target transmissivities are reached with comparably fewer layers using this method, the sensitivity and the surface E field are affected and become suboptimal. The good thing is we can do the old way just by setting Ncopies = 0 in the optimization parameters yaml file.

- An example of such a coating is in Attachment 1.

- I decided to just add the 'varL' scalar cost to the optimizer. Now we minimize for the variance in the coating stack thicknesses. As a target I started with 40% but will play with this now.

 

Attachment 1: ETM_Layers_210323_0925.pdf  27 kB  Uploaded Wed Mar 24 18:42:06 2021  | Hide | Hide all
ETM_Layers_210323_0925.pdf
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