Multilayer Interference Coating, Scattering, …attwood/srms/2007/07...Professor David Attwood Univ....

31
100 nm 10 eV 100 eV Photon energy (D. Windt, D. Stearns, J. Kortright) Wavelength Normal incidence reflectivity Natural crystals MgF 2 /Al Si C Pt, Au 1 KeV 10 KeV 10 nm 1 nm 0.1 nm Multilayer mirrors ( ) 1.0 0.5 0 mλ = 2d sin θ Ch4_F00_Feb2007.ai (W/C, T. Nguyen) Multilayer Interference Coating, Scattering, Diffraction, Reflectivity Professor David Attwood Univ. California, Berkeley Multilayer Interference Coating, Scattering, Diffraction, Reflectivity, EE290F, 6 Feb. 2007

Transcript of Multilayer Interference Coating, Scattering, …attwood/srms/2007/07...Professor David Attwood Univ....

Page 1: Multilayer Interference Coating, Scattering, …attwood/srms/2007/07...Professor David Attwood Univ. California Berkeley Multilayer Interference Coating, Scattering, Diffraction, Reflectivity,

100 nm

10 eV 100 eVPhoton energy

(D. W

indt

, D. S

tear

ns, J

. Kor

trigh

t)

Wavelength

Nor

mal

inci

denc

e re

flect

ivity

Naturalcrystals

MgF2/Al

Si C

Pt,Au

1 KeV 10 KeV

10 nm 1 nm 0.1 nm

Multilayer mirrors ( )

1.0

0.5

0

mλ = 2d sin θ

Ch4_F00_Feb2007.ai

(W/C, T. Nguyen)

Multilayer Interference Coating,Scattering, Diffraction, Reflectivity

Professor David AttwoodUniv. California, Berkeley Multilayer Interference Coating, Scattering, Diffraction, Reflectivity, EE290F, 6 Feb. 2007

Page 2: Multilayer Interference Coating, Scattering, …attwood/srms/2007/07...Professor David Attwood Univ. California Berkeley Multilayer Interference Coating, Scattering, Diffraction, Reflectivity,

Scattering by Density VariationsWithin a Multilayer Coating

Ch04_F01_Feb2007.ai

(T. Nguyen, CXRO/LBNL)

Mo/Si

Professor David AttwoodUniv. California, Berkeley Multilayer Interference Coating, Scattering, Diffraction, Reflectivity, EE290F, 6 Feb. 2007

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Scattering of Radiation by a Sinusoidal Density Distribution (Atoms or Electrons)

Ch04_F02VG.ai

na(z)

ki

ks

kd = zo2πd2θ

d

A

B

A

B

A

B

A

kiks

z

θ

Professor David AttwoodUniv. California, Berkeley Multilayer Interference Coating, Scattering, Diffraction, Reflectivity, EE290F, 6 Feb. 2007

Page 4: Multilayer Interference Coating, Scattering, …attwood/srms/2007/07...Professor David Attwood Univ. California Berkeley Multilayer Interference Coating, Scattering, Diffraction, Reflectivity,

ki

ks

kd = zo2πd2θ

Scattering from Density Variations

(4.1)

(4.2)

(4.3)

(4.4a)

(4.4b)

(4.5a)

(4.6a)or

(4.6b)

(4.5b)

Ch04_Eqs1_6VG.ai

In the long wavelength limit (λ >> a0)

Professor David AttwoodUniv. California, Berkeley Multilayer Interference Coating, Scattering, Diffraction, Reflectivity, EE290F, 6 Feb. 2007

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Ch04_MltlyrMirBragg1.ai

d

neMoSiMoSiMo

MoSi

Si

λ

θ

mλ = 2d sinθ

For normal incidence, θ = π/2, first order (m = 1) reflection λ = 2d d = λ/2if the two layers are approximately equal ∆t λ/4a quarter-wave plate coating.

Multilayer Mirrors Satisfy the Bragg Condition

Professor David AttwoodUniv. California, Berkeley Multilayer Interference Coating, Scattering, Diffraction, Reflectivity, EE290F, 6 Feb. 2007

Page 6: Multilayer Interference Coating, Scattering, …attwood/srms/2007/07...Professor David Attwood Univ. California Berkeley Multilayer Interference Coating, Scattering, Diffraction, Reflectivity,

Ch04_MltlyrMirBragg2.ai

Multilayer Mirrors Satisfy the Bragg Condition

d

neMoSiMoSiMo

MoSi

Si

λ

θ

mλ = 2d sinθ (1 – )

For normal incidence, θ = π/2, first order (m = 1) reflection λ = 2d d = λ/2if the two layers are approximately equal ∆t λ/4a quarter-wave plate coating.

4δd2

m2 λ2

Professor David AttwoodUniv. California, Berkeley Multilayer Interference Coating, Scattering, Diffraction, Reflectivity, EE290F, 6 Feb. 2007

Page 7: Multilayer Interference Coating, Scattering, …attwood/srms/2007/07...Professor David Attwood Univ. California Berkeley Multilayer Interference Coating, Scattering, Diffraction, Reflectivity,

Professor David AttwoodUniv. California Berkeley Multilayer Interference Coating, Scattering, Diffraction, Reflectivity, EE290F, 6 Feb. 2007 Ch04_HiReflecMult.ppt

High Reflectivity Multilayer Coatings Require:

• Refractive index contrast at the interfaces• Minimal absorption in the low-Z material• Thin high-Z layer where possible Γ ; ΔτH /(ΔτH + ΔτL)• Interfaces which are chemically stable with time• Minimal interdiffusion at the interfaces• Minimal interfacial roughness (no crystallite formation

within the layers, no shadowing in the coating process,surface mobility)

• Thermal stability during illumination• Chemically stable vacuum interface

(e.g., Si02 or capping layer)• Uniform coating thickness

Page 8: Multilayer Interference Coating, Scattering, …attwood/srms/2007/07...Professor David Attwood Univ. California Berkeley Multilayer Interference Coating, Scattering, Diffraction, Reflectivity,

Ch04_HiOrdrReflc.ai

High Order Reflections from a Multilayer Coating

4

3

2

1

0

Distance from surface (in periods)10d

E2

100

10–1

10–2

10–3

10–4

10–5

10–710–6

0 2.5

(Courtesy of Y. Wu and J. Underwood.)

5

Ref

lect

ivity

Scattering angle 2θ (°)7.5 10 12.5

m = 1

23

45

W/C multilayer22 layer-pairsd = 36.1 Åλ = 1.54 Å

MeasuredCalculated internal interferenceof incoming and outgoing waves

Professor David AttwoodUniv. California, Berkeley Multilayer Interference Coating, Scattering, Diffraction, Reflectivity, EE290F, 6 Feb. 2007

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Ch04_SpillerBook.ai

SOFT X-RAY OPTICSEberhard Spiller

SPIE (1994)Professor David AttwoodUniv. California, Berkeley Multilayer Interference Coating, Scattering, Diffraction, Reflectivity, EE290F, 6 Feb. 2007

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Professor David AttwoodUniv. California Berkeley Multilayer Interference Coating, Scattering, Diffraction, Reflectivity, EE290F, 6 Feb. 2007 Ch04_AngulrScan.ppt

An Angular Scan of a Multilayer Mirror Performs a Fourier-Transform of the Density Profile

Page 11: Multilayer Interference Coating, Scattering, …attwood/srms/2007/07...Professor David Attwood Univ. California Berkeley Multilayer Interference Coating, Scattering, Diffraction, Reflectivity,

Ch04_MultlyrIntrfMir.ai

Multilayer Interface MirrorsComputational Model

With refractive index n:

www.cxro.LBL.gov

(Courtesy ofJ. Underwood)

1(Vacuum)E1

zx

θ∆tA

∆tB

Ej–1

Ej

En

E2

RE1

RE2

REj–1

REj

Layer pair N

Layer pair l

2 (Material A)

3 (Material B)

j – i

j

j + 1

n – 2 (A)

n – 1 (B)n substrate

n = 1 – δ + iβ = 1 – (f1 – if2)na re λ2

2π0 0

Professor David AttwoodUniv. California, Berkeley Multilayer Interference Coating, Scattering, Diffraction, Reflectivity, EE290F, 6 Feb. 2007

Page 12: Multilayer Interference Coating, Scattering, …attwood/srms/2007/07...Professor David Attwood Univ. California Berkeley Multilayer Interference Coating, Scattering, Diffraction, Reflectivity,

Atomic Scattering Factorsfor Silicon (Z = 14)

(Henke and Gullikson; www-cxro.LBL.gov)

Ch02ApC_Tb1F07_Sept05.ai

Energy (eV) f1 f2 µ(cm2/g) 30 3.799 3.734E–01 1.865E+04 70 2.448 5.701E–01 1.220E+04 100 –5.657 4.580E+00 6.862E+04 300 12.00 6.439E+00 3.216E+04 700 13.31 1.951E+00 4.175E+03 1000 13.00 1.070E+00 1.602E+03 3000 14.23 1.961E+00 9.792E+02 7000 14.33 4.240E–01 9.075E+01 10000 14.28 2.135E–01 3.199E+01 30000 14.02 2.285E–02 1.141E+00

15

10

5

0

–5

–10

101

100

10–1

10–2

f1

f2

µ(cm

2 /g)

10 100 1000E (eV)

10000

10 100 1000 10000

10 100 1000E (eV)

10000

107

105

103

101

10–1

σa(barns/atom) = µ(cm2/g) × 46.64E(keV)µ(cm2/g) = f2 × 1498.220

0 0

0

0

Silicon (Si)Z = 14

Atomic weight = 28.086

K 1838.9 eV L1 149.7 eV L2 99.8 eV L3 99.2 eV

Edge Energies:

Professor David AttwoodUniv. California, Berkeley Multilayer Interference Coating, Scattering, Diffraction, Reflectivity, EE290F, 6 Feb. 2007

Page 13: Multilayer Interference Coating, Scattering, …attwood/srms/2007/07...Professor David Attwood Univ. California Berkeley Multilayer Interference Coating, Scattering, Diffraction, Reflectivity,

Atomic Scattering Factors forMolybdenum (Z = 42)

(Henke and Gullikson; www-cxro.LBL.gov)

Ch02ApC_Tb1F12_June2008.ai

Energy (eV) f1 f2 µ(cm2/g)

30 1.071 5.292E+00 7.736E+04 70 19.38 4.732E+00 2.965E+04 100 14.02 1.124E+00 4.931E+03 300 4.609 1.568E+01 2.292E+04 700 31.41 1.819E+01 1.140E+04 1000 35.15 1.188E+01 5.210E+03 3000 35.88 1.366E+01 1.997E+03 7000 42.11 3.493E+00 2.189E+02 10000 41.67 1.881E+00 8.248E+01 30000 42.04 1.894E+00 2.769E+01

µ(c

m2 /g

)

10 100 1000E (eV)

10000

10 100 1000 10000

10 100 1000E (eV)

10000

σa(barns/atom) = µ(cm2/g) × 159.31E(keV)µ(cm2/g) = f2 × 438.590

0 0

Edge Energies:

40

50

60

20

30

10

0

101

100

f1

f2

106

104

105

102

100

101

103

0

0

K 19999.5 eV L1 2865.5 eV M1 506.3 eV N1 63.2 eV L2 2625.1 eV M2 411.6 eV N2 37.6 eV L3 2520.2 eV M3 394.0 eV N3 35.5 eV M4 231.1 eV M5 227.9 eV

Molybdenum (Mo)Z = 42

Atomic weight = 95.940

Professor David AttwoodAST 210/EECS 213Univ. California, Berkeley

Page 14: Multilayer Interference Coating, Scattering, …attwood/srms/2007/07...Professor David Attwood Univ. California Berkeley Multilayer Interference Coating, Scattering, Diffraction, Reflectivity,

Ch04_OptomizReflcty.ai

Optimized Reflectivity with Thin “High-Z” Layers

• Sharp interfaces needed for scattering• Thin high-Z layer to minimize absorption• Low-Z layer best as a “spacer”

(Vinogradov and Zeldovich, 1977)(also see Borrmann, 1941)

(4.7)

(4.8)

high-Zlow-Z

high-Zlow-Z

high-Z

high-Zlow-Z

Professor David AttwoodUniv. California, Berkeley Multilayer Interference Coating, Scattering, Diffraction, Reflectivity, EE290F, 6 Feb. 2007

Page 15: Multilayer Interference Coating, Scattering, …attwood/srms/2007/07...Professor David Attwood Univ. California Berkeley Multilayer Interference Coating, Scattering, Diffraction, Reflectivity,

Ch04_ComputdReflec.ai

Computed Reflectivity of aW/C X-Ray Multilayer Mirror

1.0

0.8

0.6

0.4

0.2

00

(Courtesy of J. Underwood and D. Solina)

2

λ = 8.34 Åd = 22.5 ÅN = 100Γ = 1/3

4 6Glancing angle (°)

Ref

lect

ivity

8 10 12

W/C

Professor David AttwoodUniv. California, Berkeley Multilayer Interference Coating, Scattering, Diffraction, Reflectivity, EE290F, 6 Feb. 2007

Page 16: Multilayer Interference Coating, Scattering, …attwood/srms/2007/07...Professor David Attwood Univ. California Berkeley Multilayer Interference Coating, Scattering, Diffraction, Reflectivity,

Professor David AttwoodUniv. California Berkeley Multilayer Interference Coating, Scattering, Diffraction, Reflectivity, EE290F, 6 Feb. 2007 Ch04_MultilyrIntrCtg.ppt

Molybdenum as the “scattering layer”Silicon as the non-absorbing “spacing layer”

Actually an exaggeration, the complex refractive indexof each material plays a role in the reflection process

The absorption edge Si-L3 = 99.2 eV (12.5 nm)Higher photon energies are absorbed in Si,lower photon energies (longer wavelengths) are not.Typically λ = 13.4 nm or more.

Molybdenum has relatively good scattering properties in thisphoton energy (wavelength) region, with limited absorption.

Mo/Si Multilayer Interference Coating

Page 17: Multilayer Interference Coating, Scattering, …attwood/srms/2007/07...Professor David Attwood Univ. California Berkeley Multilayer Interference Coating, Scattering, Diffraction, Reflectivity,

Ch04_HiQualtyMoSi.ai

A High Quality Mo/Si Multilayer Mirror

N = 40d = 6.7 nm

Courtesy of Sasa Bajt (LLNL)ˇ

Professor David AttwoodUniv. California, Berkeley Multilayer Interference Coating, Scattering, Diffraction, Reflectivity, EE290F, 6 Feb. 2007

Page 18: Multilayer Interference Coating, Scattering, …attwood/srms/2007/07...Professor David Attwood Univ. California Berkeley Multilayer Interference Coating, Scattering, Diffraction, Reflectivity,

Professor David AttwoodUniv. California Berkeley Multilayer Interference Coating, Scattering, Diffraction, Reflectivity, EE290F, 6 Feb. 2007 Ch04_MoSi_ctngs.1.02.ppt

High Reflectivity, Thermally and Environmentally RobustMultilayers Coatings for High Throughput EUV Lithography

Page 19: Multilayer Interference Coating, Scattering, …attwood/srms/2007/07...Professor David Attwood Univ. California Berkeley Multilayer Interference Coating, Scattering, Diffraction, Reflectivity,

12.0 12.5 13.0 13.5 14.0 14.50.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8R

efle

ctiv

ity

Wavelength (nm)

Mo/B4C/Si70% at 13.5 nm

FWHM = 0.55 nm50 bilayers

Courtesy of Sasa Bajt (LLNL)ˇ

Ch04_ReflectCurv70.ai

Multilayer Mirrors HaveAchieved a Reflectivity of 70%

Professor David AttwoodUniv. California, Berkeley Multilayer Interference Coating, Scattering, Diffraction, Reflectivity, EE290F, 6 Feb. 2007

Page 20: Multilayer Interference Coating, Scattering, …attwood/srms/2007/07...Professor David Attwood Univ. California Berkeley Multilayer Interference Coating, Scattering, Diffraction, Reflectivity,

Ch04_SputtrdDepo.ai

Sputtered Deposition of a Multilayer Coating

Table rotation

Target forhigh-Z material

Target forlow-Z material

Erosionarea

Shadow mask

Magnetic flux linesconfining plasma

Target housing(negative cathode)

Mirrorsubstrate

Tablegrounded

Planetary rotation

Rotating tableMirror substrate

Target material (cathode)

Magnetron

S

NS S

Mirrorsubstrate

Mirrorsubstrate

Deposited thin film

Target housing

Targeterosionarea

Plasma ions moving towards cathode (target material)

Plasma containingmagnetic flux lines

Sputtered atoms(target material)moving toward

table

Shadowmask

SputteredSputteredparticlesparticles

Sputteredparticles

Professor David AttwoodUniv. California, Berkeley Multilayer Interference Coating, Scattering, Diffraction, Reflectivity, EE290F, 6 Feb. 2007

Page 21: Multilayer Interference Coating, Scattering, …attwood/srms/2007/07...Professor David Attwood Univ. California Berkeley Multilayer Interference Coating, Scattering, Diffraction, Reflectivity,

Ch04_DCmagntrn.ai

(Courtesy of Jim Folta, LLNL)

DC Magnetron Sputtering is Used to ReliablyDeposit Multilayer Coatings of Predictable

Center Wavelength and Excellent Uniformity

Extreme Ultraviolet Lithography

Vacuum chamber

Substrate platter

Substrate

Spinnermotorassembly

SiMo Magnetronsources

Substrates mounted on a rotating platterare swept across each sputter sourcesequentially to form the multilayer.Modulating the platter velocity providesprecision control of radial thickness distribution and absolute film thickness.The substrate is also spun fast aboutits own axis for azimuthal uniformity.

Professor David AttwoodUniv. California, Berkeley Multilayer Interference Coating, Scattering, Diffraction, Reflectivity, EE290F, 6 Feb. 2007

Page 22: Multilayer Interference Coating, Scattering, …attwood/srms/2007/07...Professor David Attwood Univ. California Berkeley Multilayer Interference Coating, Scattering, Diffraction, Reflectivity,

320 fg/µm2

1.4 mm

1.0 mm

Fe contaminatedsolar cell

Scanningstage

xy

Sample Focalspot

Fluorescentx-rays

Solid stateSi (Li) detector

M1

M2

Multilayer coatedelliptically bent

mirrors

e–

SynchrotronSource (white

radiation)

Aperture

1 µmD

focal spot

Buried, Trace Amounts of Ironin a Defective Silicon Solar Cell

Ch04_F14VG.ai

(Courtesy of A. Thompson and J. Underwood, LBNL;and R. Holm, Miles Lab)

Professor David AttwoodUniv. California, Berkeley Multilayer Interference Coating, Scattering, Diffraction, Reflectivity, EE290F, 6 Feb. 2007

Page 23: Multilayer Interference Coating, Scattering, …attwood/srms/2007/07...Professor David Attwood Univ. California Berkeley Multilayer Interference Coating, Scattering, Diffraction, Reflectivity,

Ch04_F15VG.ai

Microprobe Analysisof Contaminated Soil

pg/µm2

1 mm

1 mm

Ca

2.4

Cr Fe

ZnNi Cu

1.0

0.1 pg/µm2

0.2 pg/µm2

0.3 pg/µm2

10

(Courtesy of T. Tokunaga; and A. Thompson, LBNL)

Professor David AttwoodUniv. California, Berkeley Multilayer Interference Coating, Scattering, Diffraction, Reflectivity, EE290F, 6 Feb. 2007

Page 24: Multilayer Interference Coating, Scattering, …attwood/srms/2007/07...Professor David Attwood Univ. California Berkeley Multilayer Interference Coating, Scattering, Diffraction, Reflectivity,

Ch04_F16aVG.ai

High Resolution X-Ray DiffractionUnder High Pressure Using

Multilayer Coated Focusing Optics

Multilayercoated mirrors

10–16 keVx-rays

Film

2θDiamondanvil cell

Diamond anvil cell

e–Synchrotronradiation

Aperture Focusedx-rays

Sample under pressure(0–300 GPa)

Gasket

Pressure medium

Scatteredx-rays

H.K. Mao et al., Science 277, 1220 (29 Aug. 1997)Nature 396, 741 (24 Dec. 1998)

Professor David AttwoodUniv. California, Berkeley Multilayer Interference Coating, Scattering, Diffraction, Reflectivity, EE290F, 6 Feb. 2007

Page 25: Multilayer Interference Coating, Scattering, …attwood/srms/2007/07...Professor David Attwood Univ. California Berkeley Multilayer Interference Coating, Scattering, Diffraction, Reflectivity,

Ch04_ElasticyRheolgy.ai

NATURE 396, 741(24/31 DECEMBER 1998) www.nature.com

Professor David AttwoodUniv. California, Berkeley Multilayer Interference Coating, Scattering, Diffraction, Reflectivity, EE290F, 6 Feb. 2007

Page 26: Multilayer Interference Coating, Scattering, …attwood/srms/2007/07...Professor David Attwood Univ. California Berkeley Multilayer Interference Coating, Scattering, Diffraction, Reflectivity,

Recent Progress in Multilayer Mirrors

RecentProgMultiilyrMir.ai

80

70

60

50

40

30

20

10

01 10

Wavelength (nm)

Near-Normal Incidence Multilayer Mirrors

Peakreflectance

(%)

H2Owindow

VTi

Si

Au

CSc

Professor David AttwoodUniv. California, Berkeley Multilayer Interference Coating, Scattering, Diffraction, Reflectivity, EE290F, 6 Feb. 2007

Page 27: Multilayer Interference Coating, Scattering, …attwood/srms/2007/07...Professor David Attwood Univ. California Berkeley Multilayer Interference Coating, Scattering, Diffraction, Reflectivity,

Ch04_CassegrainTele.ai

The Cassegrain Telescope

Filmor CCDConcave

primarymirror

Convexsecondary

mirror

Sun

Professor David AttwoodUniv. California, Berkeley Multilayer Interference Coating, Scattering, Diffraction, Reflectivity, EE290F, 6 Feb. 2007

Page 28: Multilayer Interference Coating, Scattering, …attwood/srms/2007/07...Professor David Attwood Univ. California Berkeley Multilayer Interference Coating, Scattering, Diffraction, Reflectivity,

EUV Image of the Solar CoronaShowing Loops Near the Solar Limb

(Courtesy of L.Golub, Harvard-Smithsonian and T. Barbee, LLNL)

Ch04_F10VG_Sept05.ai

http://vestige.Imsal.com/TRACE

λ = 17.3 nm(71.7 eV)

Professor David AttwoodUniv. California, Berkeley Multilayer Interference Coating, Scattering, Diffraction, Reflectivity, EE290F, 6 Feb. 2007

Page 29: Multilayer Interference Coating, Scattering, …attwood/srms/2007/07...Professor David Attwood Univ. California Berkeley Multilayer Interference Coating, Scattering, Diffraction, Reflectivity,

Ch04_DynamicsSolar.ai

Dynamics of the Solar Corona

(Courtesy of L. Golub, Harvard-Smithsonian)

Professor David AttwoodUniv. California, Berkeley Multilayer Interference Coating, Scattering, Diffraction, Reflectivity, EE290F, 6 Feb. 2007

Page 30: Multilayer Interference Coating, Scattering, …attwood/srms/2007/07...Professor David Attwood Univ. California Berkeley Multilayer Interference Coating, Scattering, Diffraction, Reflectivity,

4:1reductionoptics,aspheric,multilayer

coated

Reflectivemask

Absorberpattern

Multilayermirror

Wafer to record 50 nm or smallerfeatures, over cm2 dimensions

λ = 13 nm

Extreme Ultraviolet (EUV) Lithography

Ch04_F11VG.ai

50 60 70

Extreme Ultraviolet Lithography

Professor David AttwoodUniv. California, Berkeley Multilayer Interference Coating, Scattering, Diffraction, Reflectivity, EE290F, 6 Feb. 2007

Page 31: Multilayer Interference Coating, Scattering, …attwood/srms/2007/07...Professor David Attwood Univ. California Berkeley Multilayer Interference Coating, Scattering, Diffraction, Reflectivity,

Ch04_PolarizStudies.ai

Polarization Studies of Magnetic Materials

NdFeBmagnets

Laterallygraded W/B4Cmultilayer mirror

H

DDetector(a)

(d)(c)

(b)

Fe/Crtransmissionsample

Ι0

Substrate

A

A

A

A

AB

B

B

B

H parallel kH anti-parallel k

6

4

2

0

–2

–4

–6680 690 700 710 720 730

ω (eV)ω (eV)

Rot

atio

n (d

egre

es)

6600.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7–22 mm +22 mmCenter

680 700 720 740

Ref

lect

ance

(arb

. uni

ts)

(Courtesy of J. Kortright and M. Rice, LBNL; and R. Carr, Stanford)

Professor David AttwoodUniv. California, Berkeley Multilayer Interference Coating, Scattering, Diffraction, Reflectivity, EE290F, 6 Feb. 2007