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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: 15389     Entry time: Thu Jun 11 09:37:38 2020     In reply to: 15384
Author: Jon 
Type: Update 
Category: BHD 
Subject: Conclusions on Mode-Matching Telescopes 

After further astigmatism/tolerance analysis [ELOG 15380, 15387] our conclusion is that the stock-optic telescope designs [ELOG 15379] are sufficient for the first round of BHD testing. However, for the final BHD hardware we should still plan to procure the custom-curvature optics [DCC E2000296]. The optimized custom-curvature designs are much more error-tolerant and have high probability of achieving < 2% mode-matching loss. The stock-curvature designs can only guarantee about 95% mode-matching.

Below are the final distances between optics in the relay paths. The base set of distances is taken from the 2020-05-21 layout. To minimize the changes required to the CAD model, I was able to achieve near-maximum mode-matching by moving only one optic in each relay path. In the AS path, AS3 moves inwards (towards the BHDBS) by 1.06 cm. In the LO path, LO4 moves backwards (away from the BHDBS) by 3.90 cm.

AS Path

Interval Distance (m) Change (cm)
SRMAR-AS1 0.7192 0
AS1-AS2 0.5405 0
AS2-AS3 0.5955 -1.06
AS3-AS4 0.7058 -1.06
AS4-BHDBS 0.5922 0
BHDBS-OMCIC 0.1527 0

LO Path

Interval Distance (m) Change (cm)
PR2AR-LO1 0.4027 0
LO1-LO2 2.5808 0
LO2-LO3 1.5870 0
LO3-LO4 0.3691 +3.90
LO4-BHDBS 0.2573 +3.90
BHDBS-OMCIC 0.1527 0
ELOG V3.1.3-