2011/10/3

Cheiron school 2011 , 27th Sep. 2011, SPring‐8
X‐ray beamline design Ⅱ

Optics Engineeringfor x‐ray beamline design
Haruhiko Ohashi
JASRI / SPring‐8Introduction“X‐ray beamline looks complicated ?”Storagering
inside shielding tunnel (front end )outside shielding tunnel (optics hutch )What function of each component ?

1

2011/10/3

Light source(IDs/BM)

X‐raybeamline

Front end (FE)Radiation
shield hutchLightg source( Power )Human safety

InterlocksystemBrake
Air‐bags

EngineMachine protection
Radiator
Body

Monochromator
Tailoring x‐rays

Transmission
Gear（ Power control ）Mirrors
User Interface

A vehicle

Steering wheel
Dashboard
Gear leverApplication( drive)

End station

Key issues for the beamline design
Key issues

Design components

Applications at the BL ( scientific strategy, concept )• End station( pressure, temperature,• Sample environment
magnetic field…)• Detector, data processing … ( automation )– Photon beam properties at sample
•
•
•
•
•
•

Photon energy,
gy, energy
gy resolution
Flux, flux density
Beam size
Stability( long , short term )Polarization
Spatial coherence
Priority ?
Time resolution– Human Safety & Machine protection• Protection from radiation hazard to healthg to instruments• Protection from radiation damage– Utilities––––

Time schedule
Human resources
Available budget, space, technical level
Maintenance & lifetime of BL( hardware, applications )

•
•
•
•
•
•

Light source (ID, BM)
Monochromator, higher order suppression
Monochromator
suppression…
Focusing devices… Optics (ex. mirror)
Polarizer…
Beam position monitor
Window…
RF timing, chopper…

• Radiation shielding hutch …
• Interlock system• Beam shutter…
•
•
•
•
•
•

Front end

Absorber, FE slit
Coolingl method,
h d coolingl system
Selection of light sources ( power, angular dist.)
Electronics in hutch ( detector, controller … )Embrittlement (cable, tube )Contamination on optics• Electricity, water, air, network, control• Environments ( temperature, vibration… )Management of the beamline construction2

2011/10/3

Light source(IDs/BM)

Front end (FE)X‐raybeamline

XBPM

Radiation
shield hutch

Light source
Human safety
Heat management

InterlocksystemMachine protection

Beam position monitor

Monochromator
Tailoring x‐rays

Optical design

Mirrors( for example, mirrors )User Interface

DesignMetrology

Alignment

Today’s contents

Utilities
Application

Experimental station

Heat managementgforhuman safety & machine protection↓
F t endFrontd( FE )

3

2011/10/3

Beamline components for safety

Beamline components for safety

Front end42011/10/3

SPring‐8 Tunnel

Front end (15～18m)

Schematic Layout inside the SPring‐8 Tunnel
Tunnel of the storage ring (1/16)

Front end (FE)(15～18m)

Standard
in‐vacuum undulator
Power density :500 kW/mrad2
Total power : 13 kW

Why so long FE?

5

2011/10/3

Key functions & components of FE(a) Shielding for human safety
Beam shutter (BS), collimator ( radiation shield )(b) Handling high heat load for safety Absorber, masks (to prevent BS from melting)(b’) Handling high heat load for optics
XY slit, filters ( to prevent optics from distorting )(c) Monitoring the x‐ray beam position
XBPM (x‐ray BPM ), SCM (screen monitor )(d) Protection of the ring vacuum
FCS (fast closing shutter ), Vacuum system

MBS ( = ABS + BS )is opened,
beam reaches optics hutchthrough shield wall.
Shielding wall

When we operate a main beam shutter (MBS), what happens ?
X‐ray

Absorber ( Abs )Beam shutter ( BS )to protect BS from heat load
A block of
33 kggMoveis moved

to shield you against radiation

Move

Glidcop®
(copper that is dispersion
strengthened
dispersion‐strengthened
with ultra‐fine particles of aluminum oxide)

A block of
30～46 kg
is moved

the thermal conductivity
Heavy metal
not so high(alloy of tungsten)

After Abs is fully closed, BS is closed.
After BS is fully opened, Abs is opened.
The sequences are essential to keeping safety.

ABS and BS work on ways together
to protect us from radiation when we enter the hutch.

6

2011/10/3

Revised

Other key function is to handle high heat load for optics(a) Shielding for human safety(b) Handling high heat load for safety(b’) Handling high heat load for optics(c) Monitoring the x‐ray beam position(d) Protection of the ring vacuum

Beam shutter (BS), collimator ( radiation shield )Absorber, masks (to prevent BS from melting)
XY slit, filters ( to prevent optics from distorting )XBPM (x‐ray BPM ), SCM (screen monitor )FCS (fast closing shutter ), Vacuum system

⓪
②

➀

③

Revised

These components cut off
the power to prevent
optics from distorting byheat load.

FE: “For users to take lion’s share”

Adding a spatial limitation to photon beam,
supplying only a good quality part around the central axis of ID
to transport optical system safely and stably. ①Fixed Mask Aperture ②Pre Slit Aperture
322μrad x 322μrad

The size of XY slit is set to 1.05mm□．
XY slit is installed ～30m away from ID
ID.

φ152μrad③XY Slit Aperturep
35μrad x 35μrad

Higherorder

1st harmonic
Flux Density

Power Density
Helical Mode Operation
at BL15XU

7

2011/10/3

Slit : “Too much is as bad as too little”
1st harmonic flux

How to manage
high heat load
by FE XY slit ?
Spatial distribution of power

29 kg

29 kg

Incident angle
0.08 deg(1.5 /100 )to accept the power

Handling Technology of high heat load
SPring‐8 Standard In‐Vacuum Undulator : 13.7kW, 550kW/mrad2

at SPring‐88

2011/10/3

Simulation: “better safe than sorry”

For instance, the distributions of temperature and stress of Be window at FE can be calculated
by FEA (finite element analysis ).

Key issues of FE design
1. There exists a category of the beamline front ends.
They have their proper functions, proper missions based on the principles
of human radiation safety, vacuum protection, heat‐load and radiation
damage protection of themselves.
Th haveTheyhtot deald l with
ith every moded off ringi operation
ti andd every mode
d offbeamline activities.

2. Any troubles in one beamline should not make any
negative effect to the other beamlines.
3. Strongly required to be a reliable and stable system.
We have to adopt key technologies which are reliable, stable and fully
established as far as possible.

Higher the initial cost, the lower the running cost from thelong‐range cost‐conscious point of view.

92011/10/3

Monitoringstability of photon source↓
X‐ray beam position monitor( XBPM )Where is XBPM installed ?
XBPM is installed before any spatial limitation. You hardly find it.
It is quietly monitoring beam position at any time.

Another monitor is installed
after spatial limitation.
It is useful to check the centerof XY slit. Usually it is retracted.

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2011/10/3

Revised

Structure of XBPM’s detector head

( Photo‐emission type )‐ Four blades are placed in parallel to the beam axis to reduce heat load.
‐ CVD diamond is used because of excellent heat property
Electrons from each blade of Ti/Pt/Au on diamond emitted by outer side of photon beam
The horizontal or vertical positions computed by each current

XBPM
XBPM
Surfacediamondis metalized.
for insertion
deviceof(ID)beamlinefor bending magnet (BM) beamline

Fixed‐blade style XBPM

X-ray

for SPring‐8 in‐vacuum undulator,etc.
(19 beamlines)
XBPM is installed on stable stand and stages

11

2011/10/3

RevisedHigh stability of XBPMAs the stability is compared with other monitors outside wall,
the stability of XBPM for 3 hours and 23 hours are measured.

After 3 hours

After 23 hours

V: 1.7 μm H: 3.5 μm (RMS)

V: 4.7 μm H: 3.2 μm (RMS)All Gaps are set at reference points (Minimum gaps).

Stability of the XBPM is a few microns for a day

under the same conditions ( ID‐gap, filling patter & ring current).

Long term stability of XBPM at BL47XU
Gaps is set at reference points (Minimum gaps).

12

2011/10/3

RevisedOrbit correction using XBPM

The beam
recoveredusing XBPM.
The beam lostat optics hutch.
Electron beam monitored
same orbit before.

A fixed point observation of XBPM is
helpful for a regular axis from ID.

RevisedXBPM of ID‐Gap dependence

Measured at BL47XU
with fixed‐blade style

Photo‐emission type
Reference point (Minimum gap )Gap dependence:～ 100μm for Gap : 9.6 ~ 25 mm , ～300μm for Gap : 9.6 ~ 50 mm
The position of the beam at optics hutch is fixed for changing ID gap.

What does the XBPM tell us ?

13

2011/10/3

RevisedWhat does the XBPM tell us ?
ID‐Gap minimum

ID‐Gap fully opened

Origin of ID‐gap dependence of XBPM:‐XBPM of photo‐emission type has energy dependence.
Radiation from ID changes drasticallydrastically, but not from BMs (backgrounds)‐ Backgrounds are asymmetric and usually offset.
1st harmonic:
6 ~ 18 keV,
Background: < several keV near beam axis of ID

XBPM depends on ID‐gap, filling pattern & ring current.
The results of XBPM can be compared with the same condition.

Key issues of XBPM designfor high power undulator radiation in SPring‐8

1. Dependence of ID gap, ring current, filling pattern
XBPM (photo‐emission type ) depends on these parameters.
2. High stability
XBPM has stabilityy of microns for a day.
y
3. Resolution of x‐ray beam position‐ The resolution of micron order can be monitored.
Beam divergences are ~ 20 / 5 μrad ( hor. / ver. ), which correspond to
beam sizes of ~ 400 / 100 μm ( hor. / ver. ) at XBPM position (20 m from ID).

4. Withstand high heat Load
‐ Blade of diamondMax. power density is ~ 500 kW/mrad2. Metal will melt immediately.
5. Fast Response‐ Response time of < 1 msec needs for high frequency diagnostic.
‐ Simultaneous diagnostic over beamlines is important.
Ref. of XBPM : for example, H. Aoyagi et al., “High‐speed and simultaneous photon beamdiagnostic system using optical cables at SPring‐8”, AIP Conf.Proc.705‐593 (2004).

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2011/10/3

Intensity (a.u.)

300

200

25nm
100

0
0.0

0.2

0.4

Tailoring x‐rayst application
to
li ti
↓
X‐ray mirrors
design errors,
design,errors metrology& alignment

0.6

0.8

Position (μm)
No errors

The functions of x‐ray mirrors• Deflecting• Low pass filter• Focusing• Collimatingg• Separation from γ‐ray• Branch / switch beamline• Higher order suppression• Micro‐ / nano‐ probe• Imaginggy resolution• Energy
w. multilayer or crystal mono.

15

2011/10/3

Intensity (a.u.)

300

200

25nm
100

0
0.0

0.2

0.4

Tailoring x‐rayst application
to
li ti
↓
X‐ray mirrors
design errors,
design,errors metrology& alignment

0.6

0.8

Position (μm)
No errors

Design parameters of x‐ray mirror
Requirement

the beam properties both of incident and reflected x‐rays( size, angular divergence / convergence, direction, energy region, power… )We have to know well what kinds beam irradiate on the mirror.

Design parameters• Coating material : Rh, Pt, Ni … ( w/o binder , Cr ), thickness: multilayers ( ML ), laterally graded ML• Incident angle: grazing angle ( mrad )How to select• Surface shape: flat, sphere, cylinder, elliptic …
: adaptive (mechanically bent, bimorph )• Substrate shape : rectangular,
rectangular trapezoidal…
trapezoidal• Substrate size
: length, thickness, width• w/o cooling: indirect or direct, water or LN2…
• Substrate material : Si, SiO2, SiC, Glidcop…
In addition,some errors such as figure error, roughness…

16

2011/10/3

Design parameters of x‐ray mirror
Requirement

the beam properties both of incident and reflected x‐rays( size, angular divergence / convergence, direction, energy region, power… )Design parameters• Coating material : Rh, Pt, Ni … ( w/o binder , Cr ), thickness: multilayers ( ML ), laterally graded ML• Incident angle: grazing angle ( mrad )• Surface shape: flat, sphere, cylinder, elliptic …
: adaptive (mechanically bent, bimorph )• Substrate shape : rectangular,
rectangular trapezoidal…
trapezoidal• Substrate size
: length, thickness, width• w/o cooling: indirect or direct, water or LN2…
• Substrate material : Si, SiO2, SiC, Glidcop…
In addition,some errors such as figure error, roughness…

Additional

How to select coating material and incident angle ?
Reflectivity for grazing incident mirrors
k − k2R (λ , θ , n ) = 1
k1 + k 2
k1 =

2π

λ

cos θ , k 2 =

2π

λ

2

n 2 − cos 2 θ

The complex index of refraction17

2011/10/3

Coating material (1)“the complex index of refraction”
The complex atomic scattering factor for the forward scatteringf = f1 + if 2
The complex index of refractionn = 1 − δ − iβE ∝ e − i (ϖt −kr )

Nr0λ2
δ=
f1 (λ )
2π
N 0λ2
Nr
β=
f 2 (λ )
2π
r0 =

e2
= 2.82 × 10−15 m2
4πmc

δ (×10 ‐5)β(×10 ‐7)

Si

0.488

0.744

Quartz

0.555

2.33

Pt

3.26

20.7

Au

2.96

19.5

β=

N: Number of atoms per volume

μλ
4π

μ: linear absorption coefficient

Coating material ( 2 )“total reflection”
n1 n2 = cos(θ1 ) cos(θ 2 )

θ1

θ1

θ2

θ1

θ2
θ1 > θ cSnell’s law

θ1 = θ c

θ1 = θ 2 < θ ccos(θ c ) = n = 1 − δ , cos(θ c ) → 1 − θ c 22

θ c ≅ 2δ = 1.6 ×10−2 λ ρ = 20 ρ E
θ c ( rad ), ρ ( g / cm3 ) , λ ( nm ) , E ( eV )For example,
Rh ( ρ = 12.4 g /cm3 ) λ=0.1nm, θc =5.68 mrad18

2011/10/3

Coating material ( 3 ) : “cut off, absorption”
The cut off energy of total reflection Ec
E c ( eV ) , ρ ( g / cm3 ), θ c ( mrad )Rhθi (mrad)
3
4
5
6
7
8
9
10

0.8

RefleccticityEc ≈ 20 ρ θi

1.0

0.6

L-edge0.4

K-edge0.2

Rh ( 12.4 g / cm3 )

0.0
0

5

1.0

10

15

20

Energy (keV)

25

Reflectticity

0.8

Pt ( 21.4 g / cm3 )0.6

M-edge0.4
0.2
0.0

Absorption
0

5

10

15

30

Pt
θi (mrad)
3
4
5
6
7
8
9
10

L-edge20

25

30Energy (keV)

Cut off energy, absorption → incident angle→ Opening of the mirror, length, width of mirror, power density

Additional

Atomic scattering factors, Reflectivity
You can easily find optical property in “X‐Ray Data Booklet”
by Center for X‐ray Optics and Advanced Light Source,
Lawrence Berkeley National Lab.
Lab
In the site the reflectivity of x‐ray mirrors can be calculated.

http://xdb.lbl.gov/

Many thanks to the authors !

19

2011/10/3

Surface shape (1)Purpose of the mirror• deflecting• low pass filter• focusing• collimate• meridional• sagittalg

for example,

Easy to make or cost

◎
◎
○
○
△
△
△

• flat• spherical• cylindrical• toroidal• elliptical• parabolic…
adaptive

Take care ofaberration

Surface shape (2) radius and depth2Rm =(1 p + 1 q )sin (θ i )2 sin (θ i )= Rm sin 2 (θ i )Rs =(1 p + 1 q )For parallel beam

By Fermat’s principle

q → ∞,1 / q = 0

Depth at the center D = R − R − ⎛⎜ L ⎞⎟ ≈ L
2

2⎝ 2R ⎠

2

8R

For example,
examplep=15～50m, q=5～20m θi=1～10mrad
Rm=0.1～10 km, Rs= 30～100 mm
R=1 km, L=1m → D = 125 μm

R
D

L

20

2011/10/3

Surface shape (3) elliptical
x2 y2
+
=1
a2 b2

z

For example,
15

D
Depth(μm)

s( x0, y0 )

p+q
2
1
b=
2 pq (1 − cos( 2θ )2
p2 − q2x0 =2 p 2 + 2 pq cos( 2θ ) + q 2
a=p = 975 m , q = 50 mm , θ = 3 mrad

102

y 0 = −b 1 −
5
0

q

p

u=
0

10

20

30

Position(mm)

40

50

x0
a2

b
× x0
a
2
2
a − x02⎛ s × cos( u ) + x 0 ⎞z ( s ) = − cos( u ) × b 1 − ⎜⎟ + s × cos( u ) sin( − u )a⎠⎝Precise fabrication is difficult.

( Ref * )* M.R Howells et al., “Theory and practice of elliptically bent X‐ray mirrors”, Optical Eng. 39,
2748 (2000).

Intensity (a.u.)

300

200

25nm
100

0
0.0

0.2

0.4

Tailoring x‐rayst application
to
li ti
↓
X‐ray mirrors
design errors,
errors metrology
design,& alignment

0.6

0.8

Position (μm)
No errors

21

2011/10/3“An actual mirror has some errors.”
The tolerance should be specified to order the mirror• Roughness• Density of coating material• Radius error• Figure error• Reflectivity• Beam size
• Distortion• Deformation …

The cost ( price and lead time) depends entirely on tolerance.
We must consider or discuss how to measure it.

• Deformation by self‐weight, coating and support …
• Figure error of adaptive mechanism• Misalignment of mirror• Stability of mirror’s position ( angle )• Environment• Deposition of contamination by use• Stages• Decomposition of substrate by use• Cooling system …

Additional

Contamination and removal

beforeAfter cleaning

UV / ozone cleaning
It takes from 10 min to a few hours.

222011/10/3

Errors ( 1 )“Density ρ and surface roughness σ ”
E c ≈ 20 ρ θ i

R = R0e

2

1.0

1.0

Rh
θi: 4 mrad
Density ρ
100 %
90 %
80 %

0.6
0.4

Rh
θi: 4mradrms roughness σ
0 nm
1 nm
2 nm

0.8

Reflecticity

0.8

Reflecticity⎛ 4πσ sin (θ i ) ⎞
−⎜
⎟
λ
⎝
⎠

0.6
0.4
0.2

0.2

0.0

0.0
0

5

10

15

20

25

30

0

5

10

15

20

25

30

Energy (keV)

Energy (keV)

Coating on sample wafer at the same time is helpful to evaluate the density and roughness.

Errors ( 2 )“the self‐weight deformation”
Material
SiO2
Density
2.2 g / cm3
Poisson's ratio 0.22
Young’ss modulus E = 70 Gpa
Young

L=

Bottom viewSupportedby 3 points
Thickness t = 50mm

L4
D∝
E × t3

By FEA (finite element analysis )Deformatio
on ofthe height (nm )

6
4
2
0
‐2
‐4
‐6
‐8
‐10

Position ( m )The self‐weight deformationon the surface of mirror ( SiO2 )16.7 nm PV
This value is larger than figure error byRayleigh’s rule.
( →See next page )Improvement for nano‐focusinga) Substrate → Si ( E ～ 190 GPa )b) Optimization of supporting points and methodc) Figuring in consideration of the deformation23

2011/10/3

Errors (3a)“figure error estimated by Rayleigh’s rule ”

φ = 2hk sin(θ ) → π 2

hλ / 4 = λ0.06nm (20keV) 3mrad
0.08nm (15keV) 3mrad
1 nm ( 1keV) 10mrad

2nm
3nm
12nm

8θ

h

θ

Errors (3b)“ estimation by wavefront simulation ”
p=975m, q=50mm,
θ=3mrad, L=50mm

10

Figgure error
Height error
H
(nm)
(nm)

Height(μm)
H

15

5
0

0

10

20

30

40

1
0
-1
0

10

20

30

40

50

Position (mm)Position(mm)50Position(mm)Designed surface

Errors of short range order

Intensity profiles of focusing beam by wavefront simulation
Intensity (a.u.))

300

200

25nm
100

0
0.0

0.2

0.4

0.6

Position (μm)
No errors

0.8

0.2

0.4

0.6

0.8

Position (μm)
3nmPV (0.85nmRMS)

0.2

0.4

0.6

0.8

Position (μm)
9nmPV (2.5nmRMS)

0.2

0.4

0.6

0.8

1.0

Position (μm)
30nmPV (8.5nmRMS)

Errors of short range order decreases intensity. → Roughness242011/10/3

Errors (3c)“ estimation by wavefront simulation ”
p=975m, q=50mm,
θ=3mrad, L=50mm

10

Figgure error
Height error
H
(nm)
(nm)

Height(μm)
H

15

5
0

0

10

20

30

40

1
0
-1
0

10

20

30

Position (mm)Position(mm)

50

40

50

Position(mm)Designed surface

Errors of long range order

Intensity profiles of focusing beam by wavefront simulation
Intensity (a.u.))

300

200

25nm
100

0
0.0

0.2

0.4

0.6

0.2

0.8

0.4

0.6

0.8

0.2

Position (μm)
3nmPV (1.1nmRMS)

Position (μm)
No errors

0.4

0.6

0.8

0.2

Position (μm)
9nmPV (3.2nmRMS)

0.4

0.6

0.8

1.0

Position (μm)
30nmPV (11nmRMS)

Errors of long range order loses shape.

Additional“ estimation by wavefront simulation ”
Middle range

Intensity
Intensity (a.u.)

-1.0
-1.5
0

10

20

30

40

50

0.5
0.0
-0.5
-1.0
-1.5
300

Position (mm)

250

0

10

20

30

40

150
100
50
0.2

0.4

0.6

0.8

1.0

150
100
50
0
0.0

0.2

0.4

0.6

0.8

Position (nm)Position (nm)

誤差なし
3nmPV (0.85nmRMS)
9nmPV (2.5nmRMS)
30nmPV (8.5nmRMS)

誤差なし
3nmPV (0.9nmRMS)
9nmPV (2.8nmRMS)
30nmPV (9.4nmRMS)

Intensity reduced

0.5
0.0
-0.5
-1.0
-1.5
300

200

1.0

15

Designed shape10

d DL = 25 nm

1.0

50

Position (mm)

250

200

0
0.0

1.0

0

10

20

30

40

50

Position (mm)250

Deepth(μm)

0.0
-0.5

1.5

Height error (nm)Height error (nm)0.5

Intensity (a.u.)

Height error (nm)

1.0

300

Long range

1.5

Intensity (a.u.)

Figure error

Short range
1.5

5
0

0

10

20

30

40

50

Position(mm)

200
150
100
50
0
0.0

0.2

0.4

0.6

0.8

Position (nm)1.0

Performed 25nm

誤差なし
3nmPV (1.1nmRMS)
9nmPV (3.2nmRMS)
30nmPV (11nmRMS)

Shape loses

If the figure error < 3nmPV for all spatial range,
the estimated focusing size performs 25 nm.
The value corresponds to the result of Rayleigh’s rule.

25nm

The focusing beam of 25 nm was realizedusing high precision mirror with figure error of 3 nm PV*H. Mimura, H. Yumoto, K. Yamauchi et.al, Appl. Phys. Lett. 90, 051903 (2007).

25

2011/10/3

Intensity (a.u.)

300

200

25nm
100

0
0.0

0.2

Tailoring x‐rayst application
to
li ti
↓
X‐ray mirrors
design errors,
design,errors metrology& alignment

0.4

0.6

0.8

Position (μm)
No errors

RevisedHow to evaluate the errors ?
Designed surface

Deptth(μm)

15
10
5
0

0

10

20

30

40

50

Position(mm)Errors ( long range )Figure errror(nm)

Figure errror(nm)

Errors ( short range )
1
0
-1
0

10

20

30

Position (mm)

40

50

1
0
-1
0

10

20

30

40

50

Position (mm)262011/10/3

Metrology instruments for x‐ray optics
Field of view, lateral resolution
Long /
Short /Long /
middlemiddlemiddle～1m,
1Short～10 mm, ～ 0.1 m,
1 mm Slope～10 μm,1 μm
0.1 mmFigureRoughness, figure
0.1 nmRoughness
Long Trace Profiler( LTP )
Scanning probe
microscopez (0.1nm)

RevisedScanning white lightinterferometerslope(0.1urad)Fizeau interferometerz (0.1nm) z (0.1nm)
Vertical resolution (rms)

Scanning white light interferometer
Commercially available

Interference fringe → Height

Fringes on CCD

BeamsplitterMirau orMichelson
objectivelensscanned

R f
Reference
Beam splitter
Under the test

Zygo Corp. NewVeiw®,
Bruker AXS (Veeco) Contour GT® .......

HeightFOV (=lens)～10 mmLaterall resolutionl
1 μm～
Vertical resolution 0.1 nm
Figure error
(nm)

White
light source( Lamp or LED )1
0

Short / middle range order

-1
0

10

20

30

40

50

Position (mm)272011/10/3

Fizeau interferometer

RevisedInterference pattern → Height
Monochromatic
point light source

Commercially available

Zygo Corp. VeriFire®,
4DS technologies,
FujiFILM ……

Beamsplitter

Collimator
Reference

CavityUnder the test

Figure error(nm)

Fizeau fringes on CCD
FOV (=reference) ～0.1 m
Lateral resolution ～0.1 mm
Vertical resolution 0.1 nm
10-1Long / middle range order
0

10

20

30

40

50

Position (mm)Not easy to measure large mirror

Long trace profiler ( LTP )Direction of laser reflected on the surface → Slope

Slope

d
Z '=
=
2F

d μm
F 1m
Z’ < sub-μrad

Scanning penta prism

FOV (=stage)～2 m
Lateral resolution mm～
Vertical resolution 0.1 μrad
Laser

Light source( Laser )F
Z : slopeZ’
Z : height
UnderMirror
the test

Homemade

Detectorfθ lens Positionxd on CCDor line sensor

REF for monitoring stability of system

Easy to measure slope of sub‐μrad on large mirror by NO reference
Many kinds of LTPs are developing among SR facilities.
For example, S. Qian, G. Sostero and P. Z. Takacs, Opt. Eng. 39, 304‐310 (2000).

28

2011/10/3

Additional

Figure error and slope error

Errors ( middle range )Errors ( long range )
0.2
0.1

1

0.2µrad

0.0

01
-0.1
-0.2

-0.5

Figure error
(nm)

Slop
pe error(uurad)

0.5µrad0.0

Figure error
(nm)

Slo
ope error((urad)

0.5

1

3nm

0
-1
0

10

20

30

40

50

Position (mm)

3nm

0
-1
0

10

20

30

40

50

Position (mm)Δθrms×L

Errors ( short range )
Δθ

5

L

0
-5

Lateral resolution×-10

Figure error(nm)

Slope error(urad)

10

1

3nm

0
-1
0

10

20

30

40

50

LTP :
Lateral resolution mm～
Vertical resolution 0.1 μrad

Position (mm)LTPof ESRF, APS, SPring‐8

Detector
OpticsLaser

MirrorPart of optics

Laser

Mirror
Detector

Mirror

Detector
OpticsPenta prism

Mirror29

2011/10/3

Detector

LTP
of ESRF, APS, SPring‐8

Optics (moving)
Laser

Part of optics (moving)

MirrorLaser

Optics (fixed)

Detector
Laser

MirrorPenta prism

Detector

MirrorRound robin measurement of
1m‐long toroidal mirror

Slope error profile

Figure error profile

L. Assoufid, A. Rommeveaux, H. Ohashi, K. Yamauchi, H. Mimura, J. Qian, O. Hignette, T. Ishikawa,
C. Morawe, A. T. Macrander and S. Goto, SPIE Proc. 5921-21, 2005, pp.129-140.

30

2011/10/3

Nanometer Optical Component Measuring
Machine (NOM) @HZB
Autocollimator → Slope

Homemade

Scanning

Light source( LED or laser )Under the test
F. Siewert et al.: „The Nanometer Optic Component Measuring Machine: a new Sub-nm Topography“ SRI 2003, AIP Conf. Proc.

Stitching interferometer for large mirror
Homemade

MSI

RADSI

( micro‐stitching interferometer )( relative angle determinable stitching interferometer )Microscopic
interferometer head
Test mirror

FizeauElevation
Pitch
Pitch

Roll

Horizontal scan

0.5m
Test mirror
C ll b ti with
Collaboration
ith O
Osaka
k U
Univ.,
i JTEC andd SPring‐8
SP i 8
H. Ohashi et al., Proc. Of SPIE 6704, 670405‐1 (2007).

Height error of wide range order for a long and aspherical mirror
with 1μm of lateral and 0.1 nm of vertical resolution.

Necessity is the mother of invention.

31

2011/10/3

Intensity (a.u.)

300

200

25nm
100

0
0.0

0.2

0.4

Tailoring x‐rayst application
to
li ti
↓
X‐ray mirrors
design errors,
design,errors metrology& alignment

0.6

0.8

Position (μm)
No errors

Introduction of KB mirrors
Elliptical mirrors
In 1948, P. Kirkpatrick and A. V.
Baez proposed the focusing opticalsystem.
P. Kirkpatrick and A. V. Baez, “Formation of Optical Imagesby X‐Rays”, J. Opt. Soc. Am. 38, 766 (1948).

Kirkpatrick‐Baez (K‐B) mirrors

Advantages
zLarge acceptable aperture and High efficiency
zNo chromatic aberration
zLong working distance

Disadvantages

Suitable forxx‐rayraynano‐probe

zDifficulty in mirror alignments
zDifficulty in mirror fabrications
zLarge system32

2011/10/3

Overview of
x‐ray focusing devices
focus size,
focal length[energy]

Diffraction

aberration-coma-chromatic-figure error

energyrange

Fresnel Zone Plate

12 nm,
f = 0.16 mm[0.7 keV],
30 nm,
f = 8 cm
[8 keV]

-coma
small
soft x-ray -chromatic
hard x-ray exist-figure error
small

Sputter sliced FZP

0.3 µm,f = 22 cm[12.4 keV],
0.5 µm,f = 90 cm[100 keV]

-coma
small
-chromatic
exist-figure error
large→small

2.4 µm,f = 70 cm[13.3 keV]
Bragg FZP

8-100
keV

-coma
small
mainly -chromatic
hard x-ray exist-figure error
small

energyrange

1.5 µm,f = 80 cm[18.4 keV],
1.6 µm,f = 1.3 m[15 keV]

Pressed Lens

aberration-coma-chromatic-figure error

mainlyhard x-ray

-coma
small
-chromatic
exist-figure error
largemainlyhard x-ray

-coma
small
-chromatic
exist-figure error
small

soft x-ray
hard x-ray

-coma
large
-chromatic
not exist-figure error
small
ll

0.7 µm,f = 35 cm[9 keV]<10 keV

-coma
small
-chromatic
not exist-figure error
large

95 nm,[10 keV]soft x-ray
hard x-ray

-coma
large
-chromatic
not exist-figure error
large

47nm×55nm,
f = 1cm, 2cm[21 keV]
Etching Lens

Reflection
36nm×48nm,
f=15cm,25cm[15 keV],
7 nm(1D),
f=7.5cm[20 kkeV]V]

Ki k t i k B
Kirkpatrick-Baez
Mi
Mirror-coma
16 nm(1D),large
f = 2.6 mm[19.5 keV],
mainly -chromatic
25nm×40nm, hard x-ray exist-figure error
f=2.6mm,4.7mm
small[19.5 keV]

Multilayer Laue Lens

focus size,
focal length[energy]

Refraction

Wolter Mirror

X-ray WaveguideHow small is x‐ray focused ?
For example, by elliptical mirror

S0

f1 θ

f2

dG =

f2
× S0
f1

10
5
0

l
Geometrical size

Depth(μm)

15

0

10

20

30

40

50

Position(mm)Diffraction limited size(FWHM)

d DL = λ ×0.88 f 2
l sin(θ )f 1 = 975 m , f 2 = 50 mm , θ = 3mrad , l = 50 mm , λ = 0.083 nm , S 0 = 100 μ m
Mag. = 1 / 19500 !

d G = 5 nm < d DL = 25 nm

The opening of the mirror restricts the focused size even if magnification is large.

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2011/10/3

Nano‐focusing by KB mirror
History since the century
200

180nm

Spot size (nm)

150

90nm

100

40nm
30nm 25nm
15nm

50

0
2001

2002

2003

2004
Year

2005

2006

2007

World Record of Spot Size
Focused by KB optics

7nm

Multilayer mirror

2009World Record of spot size is 7 nm (by Osaka Univ., in 2009 *).
Routinely obtained spot size is up to 30 nm.
Ref * : H. Mimura et al., “Breaking the 10 nm barrier in hard‐X‐ray focusing”, Nature Physics 6, 122 (2010).

Difficulty in mirror alignments
Focal length fφψFocal length fθψ

1st Mirror
Front View

X
X-ray

2nd Mirror
Side View

Positioning two mirrors is difficult
because there are at least 7 degree of freedom.

It is difficult to use KB mirrors.

34

2011/10/3

KB optics installed in BL29XU‐L
1st Mirror

Incident slit

2nd Mirror(Vertical focusing) (Horizontal focusing)
100mm

Undulator

Focal point

100mm

DCM
45m

102mm

98m

150mm

Side View

Glancing angle (mrad)
Mirror length (mm)Mirror aperture (μm)
Focal length (mm)Demagnification
Numerical aperture

1st Mirror
3.80
100
382
252
189
0.75x10-3

2nd Mirror
3.60
100
365
150
318
1.20x10-3

Coefficient a of elliptic function (mm)23.876 x 103

23.825 x 103

Coefficient b of elliptic function (mm)13.147

9.609

Diffraction limited focal size
(nm, FWHM)

48

29

Ref :H. Mimura, H. Yumoto, K. Yamauchi et.al, Appl. Phys. Lett. 90, 051903 (2007).

Tolerance limits of mirror alignments

Revisedφψθ

1st Mirror

2nd Mirror
Side View

Front View
250

250

Ho rizo nta l focusing
Vertical fo cu sin g

200

250

Horizontal focusing
Vertical focusing

200

150
Diffractio n l imit invertical fo cu sin g
100

50

150
Diffraction limit invertical focusing
100

-1

0

1

2

Glan cin g a ngle er rors (μrad)θ

Diffraction limit invertical focusing
100

Diffraction limit inhorizontal focusing

Diffraction limit inhorizontal focusing

0
-2

150

50

50
Diffracti on limit inh orizontal fo cu sin g-3

Horizontal focusing
Vertical focusing

200

Beam size (nm)Beam size (nm)Be am size ( nm)Severe positioning of
two mirrors is required.
The manipulator should bedesigned for these freedom of axis
with the resolution & the range.

X-ray

ψ

3

0
-200

0
-100

0

100

Perpendicularity errors (μrad)

200

-50

-30

-10

10

30

50

In-plane rotation errors (mrad)φFreedom of axis, Resolution, rangeψ

Ref: S. Matsuyama, H. Mimura, H. Yumoto et al., “Development of mirror manipulator for hard‐x‐ray nanofocusing
at sub‐50‐nm level”, Rev. Sci. Instrum. 77, 093107 (2006).

35

2011/10/3

Image on X‐ray CCD camera

L × 2θ = xx
θ=2L

1m from focal point( CCD )

Image of reflected x‐ray
Upper
8.28mm(1.150 m×3.6 mrad × 2)

x‐z planez

1508μm(380×(1/0.252))
2400μm(360×(1/0.150))

Reflected light(twice)Reflection in a verticaldirection

9.52mm(1.252m×3.8 mrad×2)

x

Focal plane

Focal point
1.92mm(0.252 m
m×3.8
3.8 mrad×2)
mrad 2)
Max 360μm
Max
380μm

Ring

Reflection in ahorizontal direction

Direct x‐ray(Mirror aperture)
1.08mm(0.150 m×3.6 mrad×2)

36

2011/10/3

Alignment of in‐plane rotation(Horizontal focusing mirror)
y‐z planez

Horizontal focusing
mirrorSide View

y
φH
2θ

X‐ray
θ

Rail
Vertical focusing
mirror(X‐ray)θ: 3.8mrad→ 2θ: 7.6mrad
Reflected angle of vertical‐focusing mirror needs to be considered,in the alignment of in‐plane rotation of horizontal‐focusing mirror.

Alignment of incident angle
・ Foucault test
Rough assessment of focusing beam profile.
This method is used for seeking focal point.
・Wire (Knife‐edge) scan method
Final assessment of focusing beam profile.

Precise adjustment of the glancing angle andfocal distance is performed until the best focusing
is achieved, while monitoring the intensity profile.

37

2011/10/3

Alignment of incident angle
X‐ray

X‐ray
CCD
cameraX‐ray Mirror

X‐ray

X‐ray
CCD
cameraX‐ray Mirror

Foucault test
Image on CCD Projection image
Downstream

Focal plane
Knife edge

Upstream
Whole bright‐area
gradually becomes dark.

Knife edge shadow

38

2011/10/3

Foucault test 1
Wire is at downstream of focal point.
Image on CCD become dark from lower side.

X‐ray CCD
cameraEd shadow
Edge
h d

X‐ray

Wire

Foucault test 2
Wire is at upstream of focal point.
Image on CCD become dark from upper side.

X‐ray CCD
camera

X‐ray

Wire

39

2011/10/3

Foucault test 3
Wire is at the focal point.
Whole bright‐area gradually becomes dark.

X‐ray CCD
camera

X‐ray

Wire

Relationshipbetween incident angle and focal position

X‐ray

Incident angle→Large ⇒ Focal point → downstream
Incident angle→Small ⇒ Focal point → upstream

40

2011/10/3

Wire (Knife‐edge) scan method for measuring beam profiles
The sharp knife edge is scanned across the beam axis, and the total intensity of the transmitting beamis recorded along the edge position.

Intensity
Detector
(PIN)

X‐ray

Wire

Intensity (arb. un
nit)

1.2

The line‐spread function of the focused
beam was derived from the numericaldifferential of the measured knife‐edge
scan profiles.

Wire scan profile

1.0
08
0.8

Differential
Diff
ti l
profile

0.6
0.4
0.2
0.0

-0.2
-200 -150 -100

-50
0
50
Position (nm)

100

150

200

Relationship between Beam size and Source size
Beam size changes depending on source size (or virtual source size).
1st Mirror

Incident slit

2nd Mirror(Vertical focusing) (Horizontal focusing)
100mm

Undulator

Focal point

100mm

DCM
45m
98m

Beam size = Source size / M
ANDBeam size ≥ Diffraction limit

102mm

150mm

Side View(M: demagnification)
10000
Vertical focusing
Horizontal focusing

Beam size is selectablefor each application.

FWHM (nm)

1000

100

10
1

10
100
TC1source
slit size
(μm)
Light
size
(μm)

1000

41

2011/10/3

Relationship between Beam size and Source size
1.410μm (Experimental)
50μm (Experimental)
100μm (Experimental)
10μm (Calculated)
50μm (Calculated)
100μm (Calculated)

Intensity (aarb. units)

1.2
1.0
0.8
0.6
0.4
0.2
0.0
-1000

Horizontal focusing-500

0Position (nm)

1.4
500

1000
10μm (Experimental)
50μm (Experimental)
100μm (Experimental)
10μm
0μ (Ca(Calculated)
cu ated)50μm (Calculated)
100μm (Calculated)

1.2
Intensity (arb. unitss)Vertical focusing

1.0
0.8
0.6
0.4
0.2
0.0
-1000

-500

0
Position (nm)

500

1000

Scanning X‐ray Fluorescence Microscope: SXFM
3000

Focused X‐ray

Intensitty (Counts)

Cl

Scanning samples

Ag

FeKα

2500

Si

2000

On a細胞中央
Cell
細胞なし
Out of Cells

S
i

1500

S

1000

Ca

500

FeKβ
Cu

ElasticZn00

X‐ray fluorescence

X‐ray spectrometer
Measurement principle

2

4
6Energy (keV)

8

10

X-ray Fluorescence spectrum

S

Zn

Scanning pitch: 1000nm Scan
area: 60×50μm

Ref: M. Shimura et al., “Element array by scanning X‐ray fluorescence microscopy after cis‐diamminedichloro‐platinum(II)treatment”, Cancer research 65, 4998 (2005).

42

2011/10/3

Key issues of x‐ray mirror design1.

To select the functions of x‐ray mirror
Deflecting, low pass filtering, focusing and collimating → Shape of the mirror

2.

To specify the incident and reflected beam properties
Energy range , flux
→ absorption,
absorption cut off energy → coating material → incident angle
The beam size and the power of incident beam
→ opening of the mirror, incident angle→ absorbed power density on the mirror → w/o cooling, substrate
Angular divergence / convergence, the reflected beam size
→ incident angle, position of the mirror ( source, image to mirror )Direction of the beam
→ effect of polarization, self‐weight deformation4.

To specify
p fy the tolerance off designedgpparameters
Roughness, density of coating material, radius error, figure error
The cost ( price and lead time) depends entirely on the tolerance.

5.

To consider the alignment
The freedom, resolution and range of the manipulator

Key issues for the beamline design
Key issues

Design components

Which application is the most important at the BL?

• End station( pressure, temperature,• Sample environment
magnetic field…)• Detector, data processing … ( automation )Can you specify who uses the property at the BL ?
•
•
•
•
•
•

–
–
–
–
–

Photon energy, energy resolution
Flux, flux density
The higher, the better ?
The smaller, the better ?
Beam size
More is NOT always better !
Polarization
Spatial coherence Simplify the property.
Time resolution Get your priorities right.

Time schedule
Human resources
Available budget, space, technical level
Maintenance for keeping performance
Lifetime of the BL ( hardware and application )What to include or not ?
What to develop or not ?

•
•
•
•
•
•

Light source (ID, BM)
Monochromator, higher order suppression
Monochromator
suppression…
Focusing devices…
Polarizer…
Stability enoughWindow…
to measure
RF timing, chopper…

• Radiation shielding hutch …
• Interlock system• Beam shutter…
•
•
•
•
•
•

Safety first !

Absorber, FE slit
Coolingl method,
h d coolingl system
Selection of light sources ( power, angular dist.)
Electronics in hutch ( detector, controller … )Embrittlement (cable, tube )Contamination on optics• Electricity, water, air, network, control• Environments ( temperature, vibration… )Simple and clear design to accelerate your research43

2011/10/3

Ongoing x‐ray beamline
X‐ray beamline looks complicated, but the function of each component is simple.
To specify the beam properties is to design the beamline.
New x‐ray beamline for next generation light source such as XFEL is newly constructed.
The components for heat management, x‐ray beam monitors and x‐ray optics
including metrology are newly developed to perform the beam properties.

Challenges at XFEL beamline :coherence preservation
wavefront disturbance or control
at wavelength techniqueultra‐shortlh & high
hi h intense
i
pulse
l
high stability
shot‐by‐shot diagnosis of x‐raystiming control of x‐ray pulse
synchronization with other source …

Acknowledgment
S. Takahashi ( front end ), H. Aoyagi (XBPM),
T. Matsushita ( interlock ),H. Takano, Y. Kohmura, T. Koyama, ( focusing devices )T. Uruga, Y. Senba ( mirrors ),S. Matsuyama, H. Yumoto, H. Mimura, K. Yamauchi( ultimate focusingg mirror,, alignmentg),
S. Goto and T. Ishikawa

44

2011/10/3

Thank you for your kind attention.

Enjoy Cheiron school
Enjoy SPring‐8
andEnjoy Japan!

45