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ZTF Field Flattener 12 segment designs 22 mm thick window

ZTF Field Flattener 12 segment designs 22 mm thick window. P. Jelinsky 2012/11/27. Revision History. Assumptions. Distance from flattener to CCD is >= 2mm Distance from filter to window between 15 and 110 mm Distance from window to flatteners between 3 and 110 mm

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ZTF Field Flattener 12 segment designs 22 mm thick window

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  1. ZTF Field Flattener12 segment designs22 mm thick window P. Jelinsky 2012/11/27

  2. Revision History

  3. Assumptions • Distance from flattener to CCD is >= 2mm • Distance from filter to window between 15 and 110 mm • Distance from window to flatteners between 3 and 110 mm • Allow distance from corrector to mirror to vary • Center Window thickness = 22mm • Window, filter and flattenersare Fused Silica • 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) • Use RMS field map with 50 x 50 points

  4. 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

  5. Schematic Filter Window 12 flatteners 12 detectors

  6. Detector Layout • Two Detectors layouts have been studied • Minimize the gap in each direction (slightly asymmetrical, need 3 detectors in Zemax) • Place detectors centers on a square grid (symmetrical, need 2 detectors in Zemax) Field locations for minimum gap Field locations for square grid

  7. Minimize the gap • RMS field map settings • Ray density = 6 • Data = Spot Radius • Wavelength = All • Method = Gauss Quad • Center field = 5 • Refer To = Centroid • X field size = 0.8655 • Y field size = 0.8655 • X field sampling = 50 • Y field sampling = 50 • Surface = Image • Use the text->Window->Copy clipboard to place the data into excel for analysis

  8. Minimize the Gap (cont) • PTF Corrector Distance = 6075.3 mm; Original Corrector Distance = 6122.4 mm • (A) = asphere • (S) = sphere

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