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Entry  Sat Jun 6 14:07:30 2020, Jon, Update, BHD, Stock-Part Mode-Matching Telescope Option ASpathStock.pdfLOpathStock.pdf
    Reply  Mon Jun 8 11:50:02 2020, Hang, Update, BHD, Astigmatism and scattering plots 6x
       Reply  Mon Jun 8 12:49:07 2020, Koji, Update, BHD, Astigmatism and scattering plots 
          Reply  Mon Jun 8 17:40:22 2020, Jon, Update, BHD, Astigmatism and scattering plots LOpathStock2.pdf
             Reply  Mon Jun 8 21:45:47 2020, Jon, Update, BHD, Astigmatism and scattering plots 
                Reply  Thu Jun 11 09:37:38 2020, Jon, Update, BHD, Conclusions on Mode-Matching Telescopes 
Message ID: 15382     Entry time: Mon Jun 8 17:40:22 2020     In reply to: 15381     Reply to this: 15384
Author: Jon 
Type: Update 
Category: BHD 
Subject: Astigmatism and scattering plots 

MM_total = (MM_vert + MM_horiz) / 2. 

The large astigmatic MM loss in the LO case is mainly due to the strong LO4 curvature (R=0.15m) with a 10 deg AOI. I looked again at whether LO1 could be increased from R=5m to the next higher stock value of 7.5m, as this would allow weaker curvatures on LO3 and LO4. However, no, that is not possible---it reduces the LO1-LO2 Gouy phase separation to only 18 deg.

There is, however, a good stock-curvature option if we want to reconsider actuating LO4 instead of LO2 (attachment 1). It achieves 99.2% MM with the OMCs, allowing positions to vary +/-1" from the current design. The LO1-LO4 Gouy phase separation is 72 deg.

Optic ROC (m) Distance from PR2 AR (m)
LO1 10 0.378
LO2 1000 2.984
LO3 10 4.571
LO4 7.5 4.926

Alternatively, we could look at reducing the AOI on LO3 and LO4 (keeping LO1-LO2 actuation).

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