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Entry  Thu Sep 9 11:25:30 2021, Paco, General, Design specs, Rerun HR coatings with n,k dispersion etm_updated.pdfitm_updated.pdf
    Reply  Thu Sep 9 20:42:34 2021, Paco, General, Design specs, Rerun HR coatings with n,k dispersion ETM210909190218.pdfITMLayers210909204021.pdf
Message ID: 24     Entry time: Thu Sep 9 11:25:30 2021     Reply to this: 25
Author: Paco 
Type: General 
Category: Design specs 
Subject: Rerun HR coatings with n,k dispersion 

[Paco]

I've re-run the HR coating designs for both ETM and ITM using interpolated dispersions (presumably at room temperature). The difference is shown in Attachment #1 and Attachment #2.

Basically, all features are still present in both spectral transmission plots, which is consistent with the relatively flat dispersions from 1 to 3 um in Silica and Tantala thin films, but the index corrections of a few percent from low-temperature estimates to room-temperature measured (?) dispersions are able to push the HR transmission up by a few (2-3) times. For instance, the ETM transmission at 2128.2 nm goes up by ~ 3. The new number is still well below what we have requested for phase I so this is in principle not an issue.

A secondary change is the sensitivity (the slope around the specified wavelength) which seems to have increased for the ETM and decreased for the ITM. This was another consideration so I'm running the optimizer to try and minimize this without sacrificing too much in transmission. For this I am using the stack as a first guess in an attempt to run fast optimization. Will post results in a reply to this post.

Attachment 1: etm_updated.pdf  205 kB  Uploaded Thu Sep 9 12:38:11 2021  | Hide | Hide all
etm_updated.pdf
Attachment 2: itm_updated.pdf  204 kB  Uploaded Thu Sep 9 12:38:22 2021  | Hide | Hide all
itm_updated.pdf
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