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ZTF Field Flattener 12 segment designs. P. Jelinsky 2012/10/02. Revision History. Assumptions. Distance from flattener to CCD is >= 3mm Distance from filter to window between 15 and 110 mm Distance from window to flattnerers between 3 and 110 mm
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ZTF Field Flattener12 segment designs P. Jelinsky 2012/10/02
Assumptions • Distance from flattener to CCD is >= 3mm • Distance from filter to window between 15 and 110 mm • Distance from window to flattnerers between 3 and 110 mm • Allow distance from corrector to mirror to vary • d/t <= 14.4 (same as QUEST camera) • Window is Fused Silica • All spherical surfaces • Aspheric surfaces did not change performance much • Optimize over 5 wavelengths in the g’, r’ bands as below (allowing a focus change). • Optimize over 9 field points in each detector • Merit function is the 2D FWHM (RMS radius * 2.3548)
Detector Gap • If t is the thickness of the flattener, d is the distance from detector to the flattener, c is the chamfer of the flattener, g is the gap between the flatteners, f is the f/# of the beam, n is the index of refraction of the glass, and s is the spacing between the detectors, then • For g = 2mm, c = 1mm, t = 5mm, d=2mm, f=2.5, n = 1.8 then s = 6 mm • I assumed 8.4 mm in the following analysis Field Flattener Detector
Schematic Filter Window 12 flatteners 12 detectors
Case I Identical Axisymmetric Flatteners R Band G Band
Case II Non Identical Axisymmetric Flatteners R Band G Band
Case III Non Identical Non Axisymmetric Flatteners R Band G Band
Case IV Non Identical Non Axisymmetric Flatteners (Window Asphere front) R Band G Band
Case V Non Identical Non Axisymmetric Flatteners(Window Asphere rear) R Band G Band
Case VI Non Identical Non Axisymmetric Flatteners(Window Asphere front Silica flattener) R Band G Band
Non Identical Non Axisymmetric Flatteners(Changing Window thickness) R Band G Band Curved 5mm filter
Non Identical Non Axisymmetric Flatteners(Changing CCD to flattener distance) R Band G Band Curved 5mm filter (28.3 mm thick window)