1. ZTF Field Flattener 12 segment designs 22 mm thick window P. Jelinsky 2012/11/27

2. Revision History 2 RevisionCommentAuthorDate 1Initial Analysis (only minimum gap orientation)pnj2012/11/27

3. Assumptions 3 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 flatteners are 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 u’g’r’i’ Wavelength (nm) Wavelength (nm) Wavelength (nm) Wavelength (nm) 325.0398.0593.0719.5 340.0432.5625.5770.75 355.0467.0658.0822.0 370.0501.5690.5873.25 385.0536.0723.0924.5

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 4 Detector Field Flattener

5. Schematic 5 Filter Window 12 flatteners 12 detectors

6. Detector Layout 6 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) DetectorX (mm)Y (mm)xfield (°)yfield (°) 14.2 0.079 150.44.20.9450.079 196.64.21.8100.079 14.250.280.0790.942 150.450.280.9450.942 196.650.281.8100.942 14.296.360.0791.806 150.496.360.9451.806 196.696.361.8101.806 21054.21.9670.079 2151.24.22.8320.079 2197.44.23.6950.079 210550.281.9670.942 2151.250.282.8320.942 2197.450.283.6950.942 210596.361.9671.806 2151.296.362.8321.806 2197.496.363.6951.806 34.2104.760.0791.963 350.4104.760.9451.963 396.6104.761.8101.963 34.2150.840.0792.825 350.4150.840.9452.825 396.6150.841.8102.825 34.2196.920.0793.686 350.4196.920.9453.686 396.6196.921.8103.686 Field locations for minimum gap DetectorX (mm)Y (mm)xfield (°)yfield (°) 14.32 0.081 150.44.320.9450.081 196.484.321.8080.081 14.3250.40.0810.945 150.4 0.945 196.4850.41.8080.945 14.3296.480.0811.808 150.496.480.9451.808 196.48 1.808 2105.124.321.9700.081 2151.24.322.8320.081 2197.284.323.6930.081 2105.1250.41.9700.945 2151.250.42.8320.945 2197.2850.43.6930.945 2105.1296.481.9701.808 2151.296.482.8321.808 2197.2896.483.6931.808 Field locations for square grid

7. Minimize the gap 7 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) 8 CaseFilterWindowFlattenerR Band FWHMG Band FWHM Corrector Distance IMeniscus (5mm)Meniscus(A)Off axis9.1µm (0.60”)13.2µm (0.88”)6263.6 mm IIMeniscus (5mm)Plano-Concave(S)Off axis9.1µm (0.61”)14.1µm (0.94”)6214.6 mm IIIMeniscus (5mm)Meniscus(A)On axis9.0µm (0.60”)14.1µm (0.94”)6263.9 mm IVMeniscus (5mm)Plano-Concave(S)On axis9.1µm (0.61”)14.0µm (0.93”)6215.0 mm VMeniscus (5mm)Meniscus(A)Identical9.0µm (0.60”)13.7µm (0.92”)6252.5 mm VIMeniscus (5mm)Plano-Concave(S)Identical9.4µm (0.63”)13.9µm (0.92”)6212.6 mm VIIPlano-Convex (5mm)Concave-Plano(S)Off axis9.4µm (0.63”)14.8µm (0.98”)6013.8 mm VIIIPlano-Convex (5mm)Concave-Plano(S)On axis9.4µm (0.63”)16.8µm (1.12”)6013.9 mm IXPlano-Convex (5mm)Concave-Plano(S)Identical9.5µm (0.63”)16.8µm (1.12”)6014.5 mm XMeniscus (10mm)Meniscus(A)Off axis9.7µm (0.65”)14.5µm (0.97”)6319.2 mm XIMeniscus (10mm)Meniscus(S)Off axis9.8µm (0.65”)15.5µm (1.04”)6250.9 mm XIIMeniscus (10mm)Meniscus(S)On axis9.8µm (0.65”)15.5µm (1.03”)6251.1 mm XIIIMeniscus (10mm)Meniscus(S)Identical10.1µm (0.67”)15.5µm (1.04”)6250.3 mm XIVPlano-Convex (10mm)Biconcave(S)Identical9.7µm (0.65”)16.8µm (1.12”)6108.7 mm XVPlano-Convex (5mm)Biconcave(S)Identical9.1µm (0.60”)14.9µm (1.00”)6107.1 mm PTF Corrector Distance = 6075.3 mm; Original Corrector Distance = 6122.4 mm (A) = asphere (S) = sphere