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Trace: • teleconsnotes20181219 • 20180629_full_focal_plane_noise_sims • report_ais • imagerteleconnotes20180221 • foregroundstelecon20210930 • teleconsnotes20180822 • foregroundstelecon20180830 • 2017-10-04 • beams_and_cl_1 • 2018-04-04
imagerteleconnotes20170919

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imagerteleconnotes20170919 [2017/09/19 13:51] – created hananyimagerteleconnotes20170919 [2017/09/27 11:11] (current) – kyoung
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 ====== Telecon 20170919 ====== ====== Telecon 20170919 ======
  
-Attending: \\ 
  
 __Agenda:__  __Agenda:__ 
-  * Focal Model + Noise (Young) +  * Focal Plane Model + Noise (Young) {{:pico_fdm_noise_model_status_20170919.pdf|Slides}}  
-  * Optics (Wen, Hills)+  * {{::coma-correction.pptx|Optics: coma correction (Hills)}} 
 +  * Optics {{::cross_dragone_sep192017.pdf|Cross Dragone Designing}}(Wen) 
 +  * {{::cbmpol_trade_interfaces.xlsx|Trade matrix}} 
 + 
 +__Notes:__ 
 + 
 +Attending: Al, Brian, Roger, Jeff F., Julian, Shaul, Karl, Qi 
 + 
 +Noise and focal plane (Karl Young) 
 +  * baseline polarization weight calculated. full sky, 4 yrs. 
 +    * accounting for DLFOV area on focal plane, not laying out wafers. 
 +    * correction from last week's pixel count.  Now 6k (open), 10.5k (crossed) 
 +  * Set edge taper to lowest band of MC pixel 
 +    * pixel size up by 1.4x, N pixels down by 2, sensitivity down by 1.4 
 +    * stop under-illuminated for higher bands in pixel 
 +      * this means a loss of resolution compared to optimum for 1.4 m mirror 
 +    * **General question to group**  What near sidelobe level is acceptable? -20 dB? -40 dB?  This sets the acceptable edge tapers. 
 +  * Comparison with Roger's TDM noise 
 +    * loading agrees 
 +    * photon noise off by 17% at low frequency, probably Bose noise difference, investigating 
 +    * phonon noise off by 30%, likely difference in safety factor 2 (Roger) vs 2.5 (Karl) 
 +    * NETs, Karl higher by 30% at 20 GHz, higher by 5% at 800 GHz 
 +      * due to where phonon noise is more significant. 
 + 
 +Coma corrected optics (Richard Hills, presented by Shaul) 
 +  * Dragone calculated equations to elimate coma in Dragone type systems 
 +  * Richard implented this via computer optimization in Zemax for the open and crossed systems 
 +  * DLFOV increases at all frequencies by, 
 +    * ~3x diameter at 900 GHz 
 +    * ~1.1x diameter at 25 GHz 
 + 
 +Redesigning crossed dragone (Qi Wen) 
 +  * Goal: avoid 'clipping' sidelobe and direct focal plane view of sky 
 +  * Requires: 
 +    * increase f/# to move focal plane away from secondary 
 +    * reduce FOV, allows focal plane to move away from secondary 
 +  * Current example has now direct view, but 2 types of 3 reflection sidelobes. 
 +  * Design work continuing.  
 + 
 +Trade-off matrix (Brian) 
 +  * trade-offs vs baselines of various aspects 
 +  * goal is to show connections between systems 
 +  * work in progress: 
 +    * add spin and precession rates 
 +    * is orbit still variable?  Or fixed to L2?
  
imagerteleconnotes20170919.1505847065.txt.gz · Last modified: 2017/09/19 13:51 by hanany

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