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Multilayer Overview. Current application Optimization of Multilayers Model Designs for GRI. Grazing Incidence Optics: Past/Present/Future. Chandra and XMM Monolitic and replicated Wolter-1 optics Single layer coated; Ir, Au. Hero, High-energy replicated optics

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multilayer overview
Multilayer Overview
  • Current application
  • Optimization of Multilayers
  • Model Designs for GRI
grazing incidence optics past present future
Grazing Incidence Optics: Past/Present/Future

Chandra and XMM

Monolitic and replicated Wolter-1 optics

Single layer coated; Ir, Au

Hero, High-energy replicated optics

InFocus, International Focusing Optics Collaboration, Pt/C

HEFT, High Energy Focusing Optics, W/Si

NuSTAR, XEUS, Constallation-X

high energy focusing telescope heft
High Energy Focusing Telescope (HEFT)

6 m focal length

Depth-graded W/Si Multilayers

Energy range 20 – 70 keV

Effective Area: ~70 cm2 @ 40 keV

Over-constrained optics: 1.2’ HPD

Field of view: 17’ @ 20 keV

Collaboration:

California institute of technology, Lawrence Livermore National Lab., Columbia University, Danish National Space Center

the heft optics
The HEFT Optics

Parameters:

Number: 3 Type : Conical Approximation optic

Size : 24 cm x 40 cm Material : W/Si, multilayers

Energy range : 5 – 69 keV

multilayers heft production
Thermally slumped AF 45 borosilicate glass

Mirror thickness, 0.3 mm

Mirror length = 10 cm

Mirror radii: 4 cm < R < 12 cm

Multilayers: HEFT Production
multilayers optimization the figure of merit
Multilayers: Optimization, The Figure Of Merit
  • A(E) effective area
    • A(E) = 2praL * [R(E,a)]2
  • [R(E,a)]2 reflectivity matrix, calculated with Nevot-Croce formalism
  • Winc(a,) angular weigthing function – Very CPU intensive
  • WE energy weigthing function = E(keV)/100 + 0.7

P. H. Mao et al, Applied Optics 38,p.4766-4775, 1999a

multilayers optimization

Power law:

Multilayers: Optimization
  • Constants a and b are uniquely determined by Dmin and Dmax
  • For a given max and min graze angle for a group Dmin and Dmax are determined by the Bragg equation
  • Multilayer recipes are optimized over:

number of bilayers N

high Z fraction G

power law index c

model designs for gri
Model Designs for GRI
  • Double reflection Radius = 0.1 – 1.0 m
        • Optimized E range = 20 – 500 keV
  • Modified Radius = 0.17 – 0.56 m
  • Double reflection Optimized E range = 40 – 500 keV
  • Single reflection Radius = 0.09 – 0.44 m
          • Optimized E range = 80 – 200 keV
  • Common Parameters:
  • Substrate thickness = 0.2 mm Mirror length = 0.6 m
  • Focal length = 150 m Material Combination = W/Si
  • Substrate = Si Radial Obs. Factor = 20%
design 1a double reflection
Design 1a: Double reflection

R = 0.1 – 1.0 m a = 0.57’ – 5.73’

design 1a
Design 1a

Total mass = 2057 kg

Number of shells = 1144

design 1b modified double reflection
Design 1b: modified double reflection

R = 0.17 – 0.56 m a = 1.02’ – 3.22’

Design 1a

Design 1b

Total mass = 824 kg

Number of shells = 582

design 2 single reflection
Design 2: Single Reflection

R = 0.09 – 0.45 m

a = 1.03’ – 5.125’

design 2
Design 2

Optionally:

Same design can be used at

F = 75 m, as a real focusing

System, but with a slight loss in effective area.

Total mass = 190 kg

Number of shells = 433

conclusions
Conclusions
  • Mass versus Effective area
    • Real focusing system or single reflection
  • Material combinations
    • W/Si chosen as a baseline
    • Pt/C, Pt/SiC, WC/SiC, ( Cu/SiC)
  • Substrate technology
    • For arcsec performance new developments in substrates are needed
    • Inherited technology from XEUS, Constallation-X
slide17

Grp 1 2 S Emin Emax dmin dmax N c Gamma Thick FOM

1 Si W Si 50 200 53.9 495.9 50 0.160 0.287 0.360 9.96

2 Si W Si 50 200 46.9 431.7 63 0.179 0.314 0.393 13.47

3 Si W Si 50 200 40.9 375.8 97 0.190 0.333 0.517 17.90

4 Si W Si 50 200 35.6 327.1 151 0.195 0.344 0.691 22.22

5 Si W Si 50 200 30.9 284.8 187 0.213 0.371 0.755 26.72

6 Si W Si 50 200 26.9 247.9 332 0.207 0.376 1.145 30.22

7 Si W Si 50 200 23.4 215.8 647 0.205 0.370 1.925 33.03

8 Si W Si 50 200 20.4 187.9 1010 0.202 0.372 2.601 32.74