ZTF Field Flattener 12 segment designs P. Jelinsky 2012/10/02

Revision History 2 RevisionCommentAuthorDate 1Initial Analysispnj2012/09/04 2Completed Case II – III added Case IV through VIpnj2012/09/18 3Added window thickness and ccd distance studypnj2012/10/02

Assumptions 3 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 * ) u’g’r’i’ Wavelength (nm) Wavelength (nm) Wavelength (nm) Wavelength (nm)

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

Schematic 5 Filter Window 12 flatteners 12 detectors

Case I Identical Axisymmetric Flatteners 6 CaseR Band FWHMG Band FWHM Curved 5mm filter14.3µm (0.95”)24.2µm (1.61”) Curved 10 mm filter15.4µm (1.03”)26.1µm (1.74”) Flat 5 mm filter 27.0µm (1.80”)35.8µm (2.39”) Flat 10 mm filter 29.5µm (1.96”)39.1µm (2.61”) R Band G Band

Case II Non Identical Axisymmetric Flatteners 7 CaseR Band FWHMG Band FWHM Curved 5mm filter11.5µm (0.77”)22.7µm (1.51”) Curved 10 mm filter12.8µm (0.85”)23.4µm (1.56”) Flat 5 mm filter26.7µm (1.78”)35.7µm (2.38”) Flat 10 mm filter29.2µm (1.95”)39.1µm (2.60”) R Band G Band

Case III Non Identical Non Axisymmetric Flatteners 8 CaseR Band FWHMG Band FWHM Curved 5mm filter11.5µm (0.75”)21.3µm (1.42”) Curved 10 mm filter13.3µm (0.88”)23.4µm (1.56”) Flat 5 mm filter24.0µm (1.60”)32.4µm (2.07”) Flat 10 mm filter 26.5µm (1.76”)35.8µm (2.38”) R Band G Band

Case IV Non Identical Non Axisymmetric Flatteners (Window Asphere front) 9 CaseR Band FWHMG Band FWHM Curved 5mm filter10.4µm (0.70”)19.6µm (1.30”) Curved 10 mm filter10.7µm (0.72”)22.4µm (1.49”) Flat 5 mm filter24.2µm (1.61”)32.6µm (2.17”) Flat 10 mm filter26.6µm (1.77”)35.9µm (2.40”) R Band G Band

Case V Non Identical Non Axisymmetric Flatteners (Window Asphere rear) 10 CaseR Band FWHMG Band FWHM Curved 5mm filter10.7µm (0.72”)19.2µm (1.28”) Curved 10 mm filter11.1µm (0.74”)21.7µm (1.45”) Flat 5 mm filter24.1µm (1.60”)32.8µm (2.19”) Flat 10 mm filter26.9µm (1.79”)36.4µm (2.42”) R Band G Band

Case VI Non Identical Non Axisymmetric Flatteners (Window Asphere front Silica flattener) 11 CaseR Band FWHMG Band FWHM Curved 5mm filter12.5µm (0.83”)18.0µm (1.20”) Curved 10 mm filter13.2µm (0.88”)20.5µm (1.37”) Flat 5 mm filter20.7µm (1.38”)30.2µm (2.01”) Flat 10 mm filter23.0µm (1.53”)33.4µm (2.23”) R Band G Band

Non Identical Non Axisymmetric Flatteners (Changing Window thickness) 12 Center Window ThicknessR Band FWHMG Band FWHM 17.6 mm8.5µm (0.57”)12.0µm (0.80”) 23.6 mm9.1µm (0.61”)13.9µm (0.93”) 28.3 mm9.4µm (0.62”)15.9µm (1.06”) 35.7 mm11.4µm (0.76”)17.7µm (1.18”) R Band G Band Curved 5mm filter

Non Identical Non Axisymmetric Flatteners (Changing CCD to flattener distance) 13 CCD to flattener distanceR Band FWHMG Band FWHM 0.0 mm8.4µm (0.56”)13.7µm (0.91”) 1.0 mm8.3µm (0.56”)15.0µm (1.00”) 2.0 mm9.4µm (0.62”)15.9µm (1.06”) 3.0 mm10.7µm (0.71”)16.4µm (1.09”) 4.0 mm12.3µm (0.82”)17.4µm (1.16”) R Band G Band Curved 5mm filter (28.3 mm thick window)