ZTF Field Flattener12 segment designs

P. Jelinsky

2012/10/02

Revision History

2

Revision Comment Author Date

1 Initial Analysis pnj 2012/09/04

2 Completed Case II – III added Case IV through VI pnj 2012/09/18

3 Added window thickness and ccd distance study pnj 2012/10/02

Assumptions

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• 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)

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

Case I Identical Axisymmetric Flatteners

6

Case R Band FWHM G Band FWHM

Curved 5mm filter 14.3µm (0.95”) 24.2µm (1.61”)

Curved 10 mm filter 15.4µm (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

Case R Band FWHM G Band FWHM

Curved 5mm filter 11.5µm (0.77”) 22.7µm (1.51”)

Curved 10 mm filter 12.8µm (0.85”) 23.4µm (1.56”)

Flat 5 mm filter 26.7µm (1.78”) 35.7µm (2.38”)

Flat 10 mm filter 29.2µm (1.95”) 39.1µm (2.60”)

R Band G Band

Case III Non Identical Non Axisymmetric Flatteners

8

Case R Band FWHM G Band FWHM

Curved 5mm filter 11.5µm (0.75”) 21.3µm (1.42”)

Curved 10 mm filter 13.3µm (0.88”) 23.4µm (1.56”)

Flat 5 mm filter 24.0µm (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

Case R Band FWHM G Band FWHM

Curved 5mm filter 10.4µm (0.70”) 19.6µm (1.30”)

Curved 10 mm filter 10.7µm (0.72”) 22.4µm (1.49”)

Flat 5 mm filter 24.2µm (1.61”) 32.6µm (2.17”)

Flat 10 mm filter 26.6µm (1.77”) 35.9µm (2.40”)

R Band G Band

Case V Non Identical Non Axisymmetric Flatteners(Window Asphere rear)

10

Case R Band FWHM G Band FWHM

Curved 5mm filter 10.7µm (0.72”) 19.2µm (1.28”)

Curved 10 mm filter 11.1µm (0.74”) 21.7µm (1.45”)

Flat 5 mm filter 24.1µm (1.60”) 32.8µm (2.19”)

Flat 10 mm filter 26.9µm (1.79”) 36.4µm (2.42”)

R Band G Band

Case VI Non Identical Non Axisymmetric Flatteners(Window Asphere front Silica flattener)

11

Case R Band FWHM G Band FWHM

Curved 5mm filter 12.5µm (0.83”) 18.0µm (1.20”)

Curved 10 mm filter 13.2µm (0.88”) 20.5µm (1.37”)

Flat 5 mm filter 20.7µm (1.38”) 30.2µm (2.01”)

Flat 10 mm filter 23.0µm (1.53”) 33.4µm (2.23”)

R Band G Band

Non Identical Non Axisymmetric Flatteners(Changing Window thickness)

12

Center Window Thickness R Band FWHM G Band FWHM

17.6 mm 8.5µm (0.57”) 12.0µm (0.80”)

23.6 mm 9.1µm (0.61”) 13.9µm (0.93”)

28.3 mm 9.4µm (0.62”) 15.9µm (1.06”)

35.7 mm 11.4µm (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 distance R Band FWHM G Band FWHM

0.0 mm 8.4µm (0.56”) 13.7µm (0.91”)

1.0 mm 8.3µm (0.56”) 15.0µm (1.00”)

2.0 mm 9.4µm (0.62”) 15.9µm (1.06”)

3.0 mm 10.7µm (0.71”) 16.4µm (1.09”)

4.0 mm 12.3µm (0.82”) 17.4µm (1.16”)

R Band G Band

Curved 5mm filter (28.3 mm thick window)