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EPIC Medium-Scale Optical Design

EPIC Medium-Scale Optical Design. Huan Tran Brad Johnson Mark Dragovan April 2009. EPIC-IM optical layout. EPIC-IM optical properties. Crossed Dragone ABS , Clover, QUIXOTE , QUIET …. Unprecedented Large FOV 30x20 degrees Extreme Compact design

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EPIC Medium-Scale Optical Design

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  1. EPIC Medium-Scale Optical Design Huan Tran Brad Johnson Mark Dragovan April 2009

  2. EPIC-IM optical layout

  3. EPIC-IM optical properties • Crossed Dragone • ABS, Clover, QUIXOTE, QUIET …. • Unprecedented Large FOV • 30x20 degrees • Extreme Compact design • Maximize resolution/throughput in shroud • Telecentric • NO refractive elements

  4. EPIC-IM optical properties Oversize mirrors “force” telecentric focal plane => cold aperture

  5. EPIC-IM aberration performance • Elliptical focal plane • Limited by vignetting in Y • Limited by aberration in X • Multiband • High Frequencies in center • 30—800 GHz • 11,000 bolometers 850 GHz 30 GHz 30 deg/ 160 cm 30 GHz 150 GHz

  6. EPIC-IM cold vs warm

  7. Main Beam Simulations • Beam shapes • No Refracting elements • Calculated with Perfect Gaussian Feed horns • Calculated for each “Hex” • Polarized beam-scale distortions • Fit Gaussians to beams • Compare to benchmarks

  8. PO co and cross–polbeams for single feed

  9. PO vs GO sanity check 30 GHz beam, from Grasp 9 Spot diagram, from Zemax

  10. Main beam effects vs benchmark EPIC-IM mirrors alone are below benchmarks w/o modulation Fig. 6.4 Histograms of main beam effects. Refer to Section 5.4.1 for definitions of each effect. Histograms are color coded by frequency. Colored Arrows denote the frequency dependant goals from table 5.4. Goals for some

  11. Sidelobes • Analyzed with Physical Optics(PO) an Geometric Theory of Diffraction (GTD) • Aperture Integration Method • Optics box • Galaxy Convolution

  12. EPIC-IM straylight

  13. EPIC-IM farsidelobes Co-pol beam, no baffling ~15d simulation time

  14. Aperture Integration method Set J =0 outside Calculate Equiv J 28d sim time

  15. Polarized Far Sidelobes (QT2 + UT2 + VT2)1/2 2 x15d sim time

  16. Galactic Contamination • In order to evaluate the effect of the signal from the far sidelobes, we convolve the qt beam maps with a 150 GHz sky model. • The beam patterns have the primary beam masked, so only the response to the sidelobes are evident in the output. • The sky data is an all sky map at long wavelengths (150 GHz). • Since the beam is asymmetric, it is necessary to rotate the beam with respect to the sky at each point to get the complete convolution. • The convolutions were done using the totalconvolver code developed by the Planck community. (Gorski et. al.) M.Dragovan

  17. (above) The 150 GHz sky map with which the beams are convolved. Units are log(uK). (below) The results of the convolution, qt beam with the above sky . Units are (uK). M.Dragovan

  18. In order to further quantify this result, we make two histograms: the number of pixels with a given intensity (left plot), and the integrated histogram giving the total number of pixels less than a given intensity (right plot). This is similar to the plots that are shown for site surveys. Goal 1nK By inspection one can see that fully 90% of the pixels are <0.2nK. M.Dragovan

  19. GTD and Polarization of sidelobes • Our Far sidelobe simulations were for 3.25 –f –l, but

  20. Conclusions • EPIC-IM has enormous throughput • Systematic beam effects are below benchmark • Sidelobes are manageable • More analysis time required to be sure

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