ZTF Field Flattener12 segment designs

22 mm thick window

P. Jelinsky

2012/11/27

Revision History

2

Revision Comment Author Date

1 Initial Analysis (only minimum gap orientation) pnj 2012/11/27

Assumptions

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• 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)

325.0 398.0 593.0 719.5

340.0 432.5 625.5 770.75

355.0 467.0 658.0 822.0

370.0 501.5 690.5 873.25

385.0 536.0 723.0 924.5

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

1)14(

22

22

fn

t

f

dcgs

Schematic

5

Filter

Window

12 flatteners

12 detectors

Detector Layout

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• 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)

Detector X (mm) Y (mm) xfield (°) yfield (°)1 4.2 4.2 0.079 0.0791 50.4 4.2 0.945 0.0791 96.6 4.2 1.810 0.0791 4.2 50.28 0.079 0.9421 50.4 50.28 0.945 0.9421 96.6 50.28 1.810 0.9421 4.2 96.36 0.079 1.8061 50.4 96.36 0.945 1.8061 96.6 96.36 1.810 1.8062 105 4.2 1.967 0.0792 151.2 4.2 2.832 0.0792 197.4 4.2 3.695 0.0792 105 50.28 1.967 0.9422 151.2 50.28 2.832 0.9422 197.4 50.28 3.695 0.9422 105 96.36 1.967 1.8062 151.2 96.36 2.832 1.8062 197.4 96.36 3.695 1.8063 4.2 104.76 0.079 1.9633 50.4 104.76 0.945 1.9633 96.6 104.76 1.810 1.9633 4.2 150.84 0.079 2.8253 50.4 150.84 0.945 2.8253 96.6 150.84 1.810 2.8253 4.2 196.92 0.079 3.6863 50.4 196.92 0.945 3.6863 96.6 196.92 1.810 3.686

Field locations for minimum gap

Detector X (mm) Y (mm) xfield (°) yfield (°)1 4.32 4.32 0.081 0.0811 50.4 4.32 0.945 0.0811 96.48 4.32 1.808 0.0811 4.32 50.4 0.081 0.9451 50.4 50.4 0.945 0.9451 96.48 50.4 1.808 0.9451 4.32 96.48 0.081 1.8081 50.4 96.48 0.945 1.8081 96.48 96.48 1.808 1.8082 105.12 4.32 1.970 0.0812 151.2 4.32 2.832 0.0812 197.28 4.32 3.693 0.0812 105.12 50.4 1.970 0.9452 151.2 50.4 2.832 0.9452 197.28 50.4 3.693 0.9452 105.12 96.48 1.970 1.8082 151.2 96.48 2.832 1.8082 197.28 96.48 3.693 1.808

Field locations for square grid

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

Minimize the Gap (cont)

8

Case Filter Window Flattener R Band FWHM G Band FWHM CorrectorDistance

I Meniscus (5mm) Meniscus(A) Off axis 9.1µm (0.60”) 13.2µm (0.88”) 6263.6 mm

II Meniscus (5mm) Plano-Concave(S) Off axis 9.1µm (0.61”) 14.1µm (0.94”) 6214.6 mm

III Meniscus (5mm) Meniscus(A) On axis 9.0µm (0.60”) 14.1µm (0.94”) 6263.9 mm

IV Meniscus (5mm) Plano-Concave(S) On axis 9.1µm (0.61”) 14.0µm (0.93”) 6215.0 mm

V Meniscus (5mm) Meniscus(A) Identical 9.0µm (0.60”) 13.7µm (0.92”) 6252.5 mm

VI Meniscus (5mm) Plano-Concave(S) Identical 9.4µm (0.63”) 13.9µm (0.92”) 6212.6 mm

VII Plano-Convex (5mm) Concave-Plano(S) Off axis 9.4µm (0.63”) 14.8µm (0.98”) 6013.8 mm

VIII Plano-Convex (5mm) Concave-Plano(S) On axis 9.4µm (0.63”) 16.8µm (1.12”) 6013.9 mm

IX Plano-Convex (5mm) Concave-Plano(S) Identical 9.5µm (0.63”) 16.8µm (1.12”) 6014.5 mm

X Meniscus (10mm) Meniscus(A) Off axis 9.7µm (0.65”) 14.5µm (0.97”) 6319.2 mm

XI Meniscus (10mm) Meniscus(S) Off axis 9.8µm (0.65”) 15.5µm (1.04”) 6250.9 mm

XII Meniscus (10mm) Meniscus(S) On axis 9.8µm (0.65”) 15.5µm (1.03”) 6251.1 mm

XIII Meniscus (10mm) Meniscus(S) Identical 10.1µm (0.67”) 15.5µm (1.04”) 6250.3 mm

XIV Plano-Convex (10mm) Biconcave(S) Identical 9.7µm (0.65”) 16.8µm (1.12”) 6108.7 mm

XV Plano-Convex (5mm) Biconcave(S) Identical 9.1µm (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