Multilayer Overview
• Current application
• Optimization of
Multilayers
• Model Designs for GRI
Grazing Incidence Optics: Past/Present/Future
Chandra and XMM
Monolitic and replicated Wolter1 optics
Hero, High-energy
replicated optics
Single layer coated; Ir, Au
InFocus, International
Focusing Optics
Collaboration, Pt/C
HEFT, High Energy
Focusing Optics, W/Si
NuSTAR, XEUS, Constallation-X
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
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
Quartz Mandrel
Glass Microsheet
a) Lay down and
machine graphite spacers
b) Lay down glass
(1)
(2)
c) Lay down and
machine graphite spacers
(3)
(4)
d) Lay down glass
Multilayers: Design
Power law:
a
Di 
(b  i )c
Multilayers: Optimization, The Figure Of Merit
 
FOM 
N
Emax
i 1 Emin
dE A(E )WE (E )
(Emax  Emin ) WE
•
•
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:
•
•
a
Di 
(b  i )c
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
D
•
hc
2E sin 
Multilayer recipes are optimized over:
number of bilayers
N
high Z fraction
G
power law index
c
Model Designs for GRI
•
Double reflection
Radius
= 0.1 – 1.0 m
Optimized E range = 20 – 500 keV
•
•
= 0.17 – 0.56 m
Modified
Radius
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
a = 0.57’ – 5.73’
R = 0.1 – 1.0 m
Group
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
Emin
120
120
120
120
120
80
80
80
80
80
40
40
40
40
40
20
20
20
20
20
Emax
500
500
500
500
500
500
500
500
500
300
300
300
300
300
180
180
180
180
180
180
dmin
66,301
59,091
52,664
46,937
41,833
37,284
33,229
29,615
26,395
39,207
34,944
31,143
27,757
24,738
36,746
32,75
29,189
26,014
23,185
20,664
dmax
309,961
276,253
246,21
219,435
195,572
261,455
233,022
207,681
185,096
164,964
294,054
262,076
233,576
208,175
185,536
330,718
294,753
262,699
234,13
208,669
N
50
27
33
51
62
106
150
206
363
87
135
187
291
453
100
195
303
378
472
737
c
0,385
0,185
0,216
0,204
0,219
0,212
0,222
0,231
0,225
0,214
0,211
0,218
0,226
0,227
0,203
0,196
0,182
0,198
0,204
0,209
Gamma
0,300
0,500
0,494
0,472
0,509
0,404
0,436
0,428
0,399
0,468
0,379
0,394
0,392
0,361
0,450
0,327
0,351
0,356
0,386
0,385
Thick
0,512
0,211
0,234
0,311
0,340
0,517
0,654
0,804
1,245
0,439
0,617
0,761
1,056
1,461
0,470
0,818
1,103
1,244
1,391
1,938
Mass
Design 1a
300
250
Kg
200
150
Mass
100
50
0
1
2 3
4 5
6 7
8 9 10 11 12 13 14 15 16 17 18 19 20
Group
Aeff @ 200 keV
Aeff/Mass/Ageom * 100cm2
Aeff/Ageom
3
Aeff/Mass
2,5
Total mass = 2057 kg
2
1,5
Number of shells = 1144
Aeff @
20 keV
200 keV
cm2
13900
2023
1
0,5
0
1
2
3
4
5
6
7
8
9 10 11 12 13 14 15 16 17 18 19 20
Design 1b: modified double reflection
R = 0.17 – 0.56 m
Emin
80
80
80
80
80
40
40
40
40
40
Emax
500
500
500
500
300
300
300
300
300
180
dmin
37,284
33,229
29,615
26,395
39,207
34,944
31,143
27,757
24,738
36,746
a  1.02’ – 3.22’
dmax
261,455
233,022
207,681
185,096
164,964
294,054
262,076
233,576
208,175
185,536
N
106
150
206
363
87
135
187
291
453
100
c
0,212
0,222
0,231
0,225
0,214
0,211
0,218
0,226
0,227
0,203
Gamma
0,404
0,436
0,428
0,399
0,468
0,379
0,394
0,392
0,361
0,450
Thick
0,517
0,654
0,804
1,245
0,439
0,617
0,761
1,056
1,461
0,470
Design 1a
Design 1b
Total mass = 824 kg
Number of shells = 582
Aeff @
20 keV
200 keV
cm2
3653
1568
Design 2: Single Reflection
R = 0.09 – 0.45 m
a = 1.03’ – 5.125’
Group
1
2
3
4
5
6
7
8
9
10
Emin
80
80
80
80
80
80
80
80
80
80
Emax
200
200
200
200
200
200
200
200
200
200
dmin
88,509
75,351
64,149
54,613
46,494
39,582
33,698
28,688
24,424
20,793
dmax
259,91
221,272
167,447
142,554
121,362
116,235
98,956
74,884
63,752
54,275
N
37
30
30
30
37
57
120
233
453
262
c
0,416
0,104
0,194
0,243
0,279
0,285
0,243
0,242
0,211
2,841
Gamma
0,494
0,606
0,651
0,636
0,594
0,478
0,434
0,383
0,390
0,339
Thick
0,478
0,263
0,241
0,213
0,228
0,304
0,524
0,856
1,379
0,891
Design 2
Aeff cm2 @
Mass
kg
20 keV
200 keV
Design 2
190
2716
1160
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
• 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)
Aeff cm2 @
Mass
kg
20 keV
200 keV
Design 1a
2057
13900
2023
Design 1b
824
3653
1568
Design 2
190
2716
1160
• Substrate technology
– For arcsec performance new developments in substrates are needed
– Inherited technology from XEUS, Constallation-X
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
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
9.96