Cheiron school 2014 , 27th Sep. 2014, SPring‐8
X‐ray beamline design Ⅱ

Optics Engineeringfor x‐ray beamline design
Haruhiko Ohashi
JASRI / SPring‐81Introduction“X‐ray beamline looks complicated?”
Storagering
Inside shielding tunnel (front end )Outside shielding tunnel (optics hutch )What function of each component ?
2

Light source(IDs/BM)

X‐raybeamline

Front end (FE)Radiation
shield hutch

Light source( Power )Human safety
EngineInterlocksystemBrake
Air‐bags

Machine protection
Radiator
Body

Monochromator
Tailoring x‐rays

Transmission
Gear（ Power control ）Mirrors
User Interface

A vehicle

Steering wheel
Dashboard
Gear leverApplication( drive)

End station
3

Key issues for the beamline design
Key issues

Design components

Applications at the BL (scientific strategy, concept)

 End station( pressure, temperature,magnetic field…)
 Sample environment
 Detector, data processing … ( automation )Photon beam properties at sample
 Photon energy, energy resolution
 Flux, flux density
Stability Beam size
( long , short term ) Polarization
 Spatial coherence
Priority ?
 Time resolution

Human Safety & Machine protection
Protection from radiation hazard to healthProtection from radiation damage to instruments

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








Light source (ID, BM)
Monochromator, higher order suppression…
Focusing devices…
Polarizer…
Window…
RF timing, chopper…

 Radiation shielding hutch …
 Interlock system
 Beam shutter…
 Absorber, FE slit
 Cooling method, cooling system
 Selection of light sources ( power, angular dist.) Electronics in hutch ( detector, controller … ) Radiation damage (cable, tube ) Contamination on optics
 Electricity, water, air, network, control
 Environments (e, vibration… )Management of the beamline construction

4

Key issues for the beamline design
Key issues

Design components

Applications at the BL (scientific strategy, concept)

 End station( pressure, temperature,magnetic field…)
 Sample environment
 Detector, data processing … ( automation )Photon beam properties at sample
 Photon energy, energy resolution
 Flux, flux density
Stability Beam size
( long , short term ) Polarization
 Spatial coherence
Priority ?
 Time resolution








Light source (ID, BM)
Monochromator, higher order suppression…
Focusing devices…
Polarizer…
Window…
RF timing, chopper…

You have to describe beam parameters for experiments.
Sometimes these requests are competing.

Management of the beamline construction

5Key issues for the beamline design
Key issues

Design components

Applications at the BL (scientific strategy, concept)

 End station( pressure, temperature,magnetic field…)
 Sample environment
 Detector, data processing … ( automation )Photon beam properties at sample
 Photon energy, energy resolution
 Flux, flux density
Stability Beam size
( long , short term ) Polarization
 Spatial coherence
Priority ?
 Time resolution








Light source (ID, BM)
Monochromator, higher order suppression…
Focusing devices…
Polarizer…
Window…
RF timing, chopper…

You have to describe beam parameters for experiments.
Sometimes these requests are competing.
↓
You have to assign priorities to the beam performance.

Management of the beamline construction

6

Key issues for the beamline design
Key issues

Design components

Applications at the BL (scientific strategy, concept)

 End station( pressure, temperature,magnetic field…)
 Sample environment
 Detector, data processing … ( automation )Photon beam properties at sample
 Photon energy, energy resolution
 Flux, flux density
Stability Beam size
( long , short term ) Polarization
 Spatial coherence
Priority ?
 Time resolution

Human Safety & Machine protection
Protection from radiation hazard to healthProtection from radiation damage to instruments

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








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

 Radiation shielding hutch …
 Interlock system
 Beam shutter…
Front end
 Absorber, FE slit
 Cooling method, cooling system
 Selection of light sources ( power, angular dist.) Electronics in hutch ( detector, controller … ) Radiation damage (cable, tube ) Contamination on optics
 Electricity, water, air, network, control
 Environments (e, vibration… )Management of the beamline construction

7

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
8

Heat managementforhuman safety & machine protection↓
Front end
( FE )
9SPring‐8 Tunnel

Front end (15～18m)

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

Front end (FE)Standard
in‐vacuum undulator
Power density :(15～18m)

500 kW/mrad2
Total power : 13 kW

Why so long FE?
11

Key functions & components of FE Shielding for human safety
 Handling high heat load for safety
 Handling high heat load for optics
 Monitoring the x‐ray beam position
 Protection of the ring vacuum

Beam shutter (BS), collimator
Absorber, masks
XY slit, filters
XBPM (x‐ray BPM ), SCM (screen monitor )FCS (fast closing shutter ), Vacuum system

BL
Experimental
OpticsStationShielding wall

12

What’s “Main Beam Shutter” ?

13Key functions & components of FE Shielding for human safety
 Handling high heat load for safety

For safety

Beam shutter (BS), collimator
Absorber, masks

13kW

BL
Experimental
OpticsStationShielding wall

MBS ( = ABS + BS ) is closed → MBS accepts the incident power form ID.
14

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

For safety

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

to shield you against radiation

Move

Glidcop®
(copper that is 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 BS is fully opened, Abs is opened.
After Abs is fully closed, BS is closed.
The sequences are essential to keeping safety.

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

15

What components remove most “power” from ID ?

For managing
heat load

Total power from ID = 14 kW
The power through FE section = 0.6 kW

14kW

0.6kW

BL
Experimental
OpticsStation16

What components remove most “power” from ID ?

For managing
heat loadAbsorber, masks (to prevent BS from melting)
XY slit, filters (to prevent optics from distorting)
These components （①，② and ③) cut off the power to prevent optics from distorting by heat load.
□7mm

14kW

φ4mm

13kW

6kW
②

➀
□1mm

0.6kW

BL
Experimental
OpticsStation③
Someone may enlarge opening of XY slit to get more “flux” → You can NOT get it!

17

FE: “For users to take lion’s share”

For managing
heat load

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
322rad x 322rad

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

152rad③XY Slit Aperture
35rad x 35radHigherorder

1st harmonic
Flux Density

Power Density
Helical Mode Operation
at BL15XU

18

For managing
heat load

Comparison of the Spatial Distribution
between 1st harmonic Flux density and Power density
Sandard in vacuum undulator
K=2.6 E1st=4.3keV

Horizontal
Vertical

500

1.0
300

200

0.5

(kW/mrad2)

400

Power density(photons/sec/mrad2/0.1b.w.)

Flux density

18
1.5
1.510100

0.0
0

V: 15 μrad
= 0.5mm / 30m

FE slit

50

100

150

0
200

V (rad)

H: 40 μrad
= 1.2mm / 30m
19How to manage high heat load
by FE XY slit ?

For managing
heat load

1st harmonic flux

Spatial distribution of power

Incident angle
0.08 deg(1.5 /100 )

29 kg

29 kg

SR

20

If an optical component is irradiatedby too much power ….
One user opened FE slit excessively.
2kW

Melted3 mm

Damaged area

Slit : “Too much is as bad as too little”
21

Handling Technology of high heat load

For managing
heat load

at SPring‐8
SPring‐8 Standard In‐Vacuum Undulator : 13.7kW, 550kW/mrad2

22

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 ).

23

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.
They have to deal with every mode of ring operation and every mode ofbeamline 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.

24Monitoringstability of photon source↓
X‐ray beam position monitor( XBPM )25

Where is XBPM installed ?
XBPM is installed before any spatial limitation. You hardly find it.
It is quietly monitoring beam position at any time.

BL
Experimental
OpticsStation26

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

27

Fixed‐blade style XBPM

X-ray

for SPring‐8 in‐vacuum undulator,etc.
(19 beamlines)
XBPM is installed on stable stand and stages
28

High 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
V: 1.7 m H: 3.5 m (RMS)

After 23 hours
V: 4.7 m H: 3.2 m (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).

29

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

30

Orbit 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.
31

ID‐Gap dependence of XBPM
Measured at BL47XU
with fixed‐blade style

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

What does the XBPM tell us ?

32

What 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 drastically, 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.

33

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 stability of microns for a day.
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).
34

Intensity (a.u.)

300

200

25nm
100

0
0.0

0.2

0.4

0.6

Position (m)
No errors

Tailoring x‐rays
to application↓
X‐ray mirrors
design, errors, metrology& alignment

0.8

35

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

36

Intensity (a.u.)

300

200

25nm
100

0
0.0

0.2

0.4

0.6

Position (m)
No errors

Tailoring x‐rays
to application↓
X‐ray mirrors
design, errors, metrology& alignment

0.8

37

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, 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…
38

How to select coating material and incident angle ?
Reflectivity for grazing incident mirrors
k1  k 2
R ( ,  , n ) 
k1  k 2
k1 

2



cos  , k 2 

2



2

n 2  cos 2 

The complex index of refraction

39

Coating material (1)“the complex index of refraction”
The complex atomic scattering factor for the forward scatteringf  f1  if 2

Small
for x‐ray region

The complex index of refractionn  1    i

Nr0f1 ( )
2
2
Nr0

f 2 ( )2

Ee i (t  kr )

2

e2
15
r0 

2
.
82

10
m
2
4mc
N: Number of atoms per volume

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



4

μ: linear absorption coefficient40Coating material ( 2 )“total reflection”
cos(1 ) cos( 2 )  n2 n1

1←Snell’s law
Incident angle smaller than critical angle,
Total reflection occurs

12
1   c2  01   c2

1
1   ccos( c )  n  1   , cos( c )  1   c 22

 c  2  1.6 10    20  E
2θc ( rad ), ρ ( g / cm3 ) , λ ( nm ) , E ( eV )For example,
Rh ( ρ = 12.4 g /cm3 ) λ=0.1nm, θc =5.68 mrad
41

Coating material ( 3 ) : “cut off, absorption”
The cut off energy of total reflection Ec
Ec ( eV ) , ρ ( g / cm3 ), θc ( mrad )0.8

Reflecticity

Ec  20  i

1.0

0.6

L-edge0.4

K-edge0.2

Rh ( 12.4 g / cm3 )Rh
i (mrad)
3
4
5
6
7
8
9
10

0.0
0

5

1.0

10

15

20

Energy (keV)25Pt
i (mrad)
3
4
5
6
7
8
9
10

L-edgeReflecticity

0.8

Pt ( 21.4 g / cm3 )0.6

M-edge0.4
0.2
0.0

Absorption
0

5

10

15

30

20

25

30

Energy (keV)

Cut off energy, absorption → incident angle→ Opening of the mirror, length, width of mirror, power density 42

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.
In the site the reflectivity of x‐ray mirrors can be calculated.

http://xdb.lbl.gov/

Many thanks to the authors !
43

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

for example,

Easy to make or cost

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

◎
◎
○
○
△
△
△

Take care ofaberration

44Surface shape (2) radius and depth2Rm 1 p  1 q sin  i 
2 sin  i 
2
 Rm sin  i 
Rs 
1 p  1 q 

For parallel beamq  ,1 / q  0

Depth at the center
D  R

For example,

By Fermat’s principle

2

R
2

L
L
R   8R
2
2

p=15～50m, q=5～20m, θi=1～10mrad
Rm=0.1～10 km, Rs= 30～100 mm
Rm= 1 km, L=1m
→ D = 125 μm
Rs=30 mm, L=20mm → D = 1.7 mm

DL

Sagittal focusing mirror
Rs～30mm45

Basic geometry

ESRF

The optical path length :spherical or cylindrical shape → not constantelliptical shape → constantSFpby courtesy of Ch. Morawe

q

46

ESRF

Mirror optics

Elliptical shape is suitable for point‐to‐point focusing.

p1

q2

q1

p2

Constant optical path = p1+q1 = p2+q2 =・・・
by courtesy of Ch. Morawe

47

Surface shape (3) elliptical
2

2

x
y
 2 12abzp( x0, y0 )For example,p  975 m , q  50 mm ,   3 mrada

Depth(m)

15

x0 
10

pq
, b  sin( ) pq2
p2  q2
2 p 2  2 pq cos( 2 )  q 22

50

y 0  b 1 
0

10

20

s

q

30

Position(mm)

40

50

x0
,u 
2
a

b
 x0
a
2
a 2  x02

 s  cos( u )  x 0 z ( s )   cos( u )  b 1    s  cos( u ) sin(  u )aPrecise fabrication is not easy.

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

48

Elliptical mirror mechanically bent
using trapezoidal substrate
Trapezoidal mirror (L170mm)

Trapezoidal mirror (L540mm)

Dynamically bent KB mirror
at ESRFLong bent focusing mirror
at SPring‐8

These system works fine to focus micro beam.
49

ESRF

Mirror optics

Elliptical shape is suitable for point‐to‐point focusing.

Opening of a mirror restricts focusing size.
→ see #83
by courtesy of Ch. Morawe

50

Multilayer coating mirror
advantages
enlarge opening of a mirror
higher critical angle
moderate energy resolution

q

q

A
B

L
L*sinqdisadvantages
chromatic
damage ?
cost ?
“Juni Hito‐e”
a 12‐layered ceremonial kimono
51

ESRF

Multilayer optics

To enlarge opening of a mirror, multilayer is useful.

by courtesy of Ch. Morawe

52

X‐ray multilayer reflectivity

ESRF→ see #41

 c  20  E  0.25 deg W : ρ=19.25g/cm3

Numerical calculations
Main features• Bragg peaks and fringes due to interference• Positions depend on E and Λ• Intensities depend on Δρ, N, σ…
Bragg Eq .&Snell’s law

Corrected Bragg equationm    2    n2  n1 cos 2 
2For θ >> θC →

n1
L

2

m    2    sin 

q

q

A
B

n2
L*sinq

Two materials of high and low atomic number are alternately deposited to maximize the difference in electron density.
→ The multilayer coating allows larger incident angle for x‐rays depending on the periodicity (Λ).
by courtesy of Ch. Morawe
53

n1

1
 n2

1
2

ଶ

Bragg’s eq.

ଶ

ଶ
ଶ
ଶ

ଶ

Snell’s law :

ଶ

ଵ
ଶ

ଶ

ଶ
ଵ

ଶ
ଵ

ଶ

ଶ

ଵ
54

ESRF

X‐ray multilayer characterization

Transmission electron microscopy (TEM)• Fabrication errors• Roughness evolution• Crystallinity• Interface diffusion[W/B4C]50

Complementary to x‐ray measurements !

R. Scholz, MPI Halle, Germany

by courtesy of Ch. Morawe

55

ESRF

by courtesy of Ch. Morawe

Energy resolution of multilayers

Ch. Morawe et al, Nucl. Instr. And Meth. A 493, 189 (2002) 56

ESRF

X‐ray multilayer design

Period number N: can control reflectivity and energy resolution.
Peak versus integrated reflectivity:• Rpeak increases with N up to extinction• ΔE/E decreases ~ 1/N in kinematical range• Rint is maximum before extinction
High and low resolution MLs

Optimize N according to needs !

by courtesy of Ch. Morawe

57

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, 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…
58

Intensity (a.u.)

300

200

25nm
100

0
0.0

0.2

0.4

0.6

Position (m)
No errors

Tailoring x‐rays
to application↓
X‐ray mirrors
design, errors, metrology& alignment

0.8

59

“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
 Decomposition of substrate by use • Manipulator• Cooling system …
60

Contamination and removal
beforeAfter cleaning

UV / ozone cleaning
It takes from 10 min to a few hours.
61Errors ( 1 )“Density ρ and surface roughness σ ”
E c  20   i

R  R0e

2

1.0

1.0

Rh
i: 4 mrad
Density ρ
100 %
90 %
80 %

0.6
0.4

Rh
i: 4mradrms roughness σ
0 nm
1 nm
2 nm

0.8

Reflecticity

0.8

Reflecticity

 4 sin  i  






0.6
0.4
0.2

0.2

0.0

0.0
0

5

10

15

20

Energy (keV)

25

30

0

5

10

15

20

25

30

Energy (keV)

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

62

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

4Supported by 2 lines

L
D
3
E t

This value for nano‐focusing is larger than figure error by Rayleigh’s rule.

Improvement for nano‐focusing( →See next page )a) Substrate → Si ( E ～ 190 GPa )b) Optimization of supporting points and methodc) Figuring the surface in consideration of the deformation

63

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

  hk sin( )   2h / 4  

0.06nm (20keV) 3mrad
0.08nm (15keV) 3mrad
1 nm ( 1keV) 10mrad

2nm
3nm
12nm

8

h


64

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

10Figure error
Height error
(nm)
(nm)

Height(m)

15

5
0

0

10

20

30

40

1
0
-1
0

10

20

30

40

50

Position (mm)Position(mm)50Position(mm)Errors of short range order

Designed surface

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 (m)
No errors

0.8

0.2

0.4

0.6

0.8

Position (m)
3nmPV (0.85nmRMS)

0.2

0.4

0.6

0.8

Position (m)
9nmPV (2.5nmRMS)

0.2

0.4

0.6

0.8

1.0

Position (m)
30nmPV (8.5nmRMS)

Errors of short range order decreases intensity. → Roughness
65Errors (3c)“ estimation by wavefront simulation ”
p=975m, q=50mm,
θ=3mrad, L=50mm

10Figure error
Height error
(nm)
(nm)

Height(m)

15

5
0

0

10

20

30

40

1
0
-1
0

10

20

30

Position(mm)4050Position (mm)50Position(mm)Errors of long range order

Designed surface

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 (m)
No errors

0.8

0.2

0.4

0.6

0.8

Position (m)
3nmPV (1.1nmRMS)

0.2

0.4

0.6

0.8

Position (m)
9nmPV (3.2nmRMS)

0.2

0.4

0.6

0.8

1.0

Position (m)
30nmPV (11nmRMS)

Errors of long range order loses shape. → Figure66

“ estimation by wavefront simulation ”
Middle range

Intensity
Intensity (a.u.)

0.0
-0.5
-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

Depth(m)

0.5

1.5

Height error (nm)Height error (nm)1.0

Intensity (a.u.)

Height error (nm)

1.5

300

Long range

1.5

Intensity (a.u.)

Figure error

Short range

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).

67

Intensity (a.u.)

300

200

25nm
100

0
0.0

0.2

0.4

0.6

Position (m)
No errors

Tailoring x‐rays
to application↓
X‐ray mirrors
design, errors, metrology& alignment

0.8

68

How to evaluate the errors ?
Designed surface

Depth(m)

15
10
5
0

0

10

20

30

40

50

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

Figure error(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)69

Metrology instruments for x‐ray optics
Field of view, lateral resolution
Long /
Short /Long /
middlemiddlemiddle～1m,
Short～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)

Scanning white lightinterferometer

Fizeau interferometerz (0.1nm) z (0.1nm)
Vertical resolution (rms)slope(0.1μrad)70

Scanning white light interferometer
Commercially available

Interference fringe → Height

Fringes on CCD

BeamsplitterMirau orMichelson
objectivelensscannedReference
Beam splitter
Under the test

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

HeightFOV (=lens) 50um～10 mm
Lateral resolution 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)71

Fizeau interferometer
Interference pattern → Height
Monochromatic
point light source

Commercially available

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

BeamsplitterFizeau fringes on CCD
FOV (=reference) ～0.1 m
Lateral resolution ～0.1 mm
Vertical resolution 0.1 nm
Figure error(nm)Collimator
Reference

CavityUnder the test

1
0
-1

Long / middle range order
0

10

20

30

40

50

Position (mm)Not easy to measure large mirror

72

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 )FZ’ : slope
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).

73

Figure error and slope error
Errors ( middle range )Errors ( long range )0.2

10.2µrad

0.0

-0.1
-0.2

-0.5

Figure error(nm)

Slope error(urad)

0.5µrad

0.0

0.1

Figure error(nm)

Slope 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)Errors ( short range )～Δθrms×L

5

Δθ

0
-5

L

Lateral resolution×-10

Figure error(nm)

Slope error(urad)

10

1

3nm

0
-1
0

10

20

30

Position (mm)

40

50

LTP :
Lateral resolution mm～
Vertical resolution 0.1 μrad74

LTP
of ESRF, APS, SPring‐8

Detector
OpticsLaser

MirrorPart of optics

Laser

Mirror
Detector

Mirror

Detector
OpticsPenta prism

Mirror75

Detector

LTP
of ESRF, APS, SPring‐8

Optics (moving)
Laser

Part of optics (moving)

MirrorLaser

Optics (fixed)

Detector
Laser

MirrorPenta prism

Detector

Mirror76

Round 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.
77

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.
78

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
Collaboration with Osaka Univ., JTEC and SPring‐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.
79

Intensity (a.u.)

300

200

25nm
100

0
0.0

0.2

0.4

0.6

Position (m)
No errors

Tailoring x‐rays
to application↓
X‐ray mirrors
design, errors, metrology& alignment

0.8

80

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
Large acceptable aperture and High efficiency
No chromatic aberration
Long working distance

Disadvantages

Suitable forx‐raynano‐probeDifficulty in mirror alignments
Difficulty in mirror fabrications
Large system
81

Overview of
x‐ray focusing devices
Diffraction

focus size,
focal length[energy]energyrange

aberration-coma-chromatic-figure error

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

Multilayer Laue Lens

8-100
keV

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

16 nm(1D),-coma
f = 2.6 mm
large[19.5 keV],
mainly -chromatic
exist
25nm×40nm, hard x-ray
f=2.6mm,4.7mm-figure error[19.5 keV]
small

Refraction

Pressed Lens

focus size,
focal length[energy]
1.5 µm,f = 80 cm[18.4 keV],
1.6 µm,f = 1.3 m[15 keV]
47nm×55nm,
f = 1cm, 2cm[21 keV]

Etching Lens

energyrange

aberration-coma-chromatic-figure error

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

Reflection
7 nm×8nm,
f=7.5cm[20 keV]

-coma
large
soft x-ray -chromatic
hard x-ray
not exist-figure error
small

0.7 µm,f = 35 cm[9 keV]<10 keV

-coma
small
-chromatic
not exist-figure error
large

95 nm,[10 keV]

-coma
large
soft x-ray -chromatic
hard x-ray
not exist-figure error
large

Kirkpatrick-Baez Mirror

Wolter Mirror

X-ray Waveguide82How small is x‐ray focused ?
For example, by elliptical mirror

S0
p



Depth(m)15qqd G   S0
p

5
0

l
Geometrical size

10

0

10

20

30

40

50

Position(mm)Diffraction limited size(FWHM)

0.88q
d DL   
l sin( )p  975 m , q  50 mm ,   3mrad , l  50 mm ,    nm , S 0  100 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.

83

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

World Record of Spot Size
Focused by KB optics

2007

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).
84Difficulty in mirror alignments
Focal length fφψFocal length fθψ

1st Mirror
Front View

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.
85

KB optics installed in BL29XU‐L
1st Mirror

Incident slit

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

Undulator

Focal point

100mm

DCM
45m
98m

102mm

150mm

Side View

Glancing angle (mrad)
Mirror length (mm)Mirror aperture (m)
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).
86

Tolerance limits of mirror alignments
ψ




ψ

θ

1st Mirror

2nd Mirror
Side View

Front View
250

200

～0.1 μrad
Beam size (nm)Be am size ( nm)250

Ho rizo nta l focusing
Vertical fo cu sin g

200

Severe positioning of
two mirrors is required.
X-ray
The manipulator should bedesigned for these freedom of axis
with the resolution & the range.

150
Diffractio n l imit invertical fo cu sin g
100

50

250

Horizontal focusing
Vertical focusing～10 μrad～1000 μrad150
Diffraction limit invertical focusing
100

Diffracti on limit inh orizontal fo cu sin g-1

0

Diffraction limit invertical focusing
100

Diffraction limit inhorizontal focusing

Diffraction limit inhorizontal focusing

0
-2

150

50

50

-3

Horizontal focusing
Vertical focusing

200

Beam size (nm)



φ

1

2

Glan cin g a ngle er rors (rad)

Errors of 

3

0
-200

0
-100

0

100

Perpendicularity errors (rad)
Perpendicularity
 rad)errors 

200

-50

-30

-10

10

30

50

In-plane rotation errors (mrad)
In-planerotation mrad)errors 

Freedom of axis, Resolution, range
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).

87

A typical manipulator of KB optics
Vertically focusing
mirror (Rh on Si)

The center ofpitching axis byflexure hinge

Horizontally
focusing mirror(Rh on SiO2)

 Precise manipulation of mirrors
For example,
 Highly stable system
 Resolution of pitching axis = 0.1 μrad
 Ultra‐high vacuum→ Res. of the actuator at 100 mm = 10 nm( or He environment ) The focal length = 1 m and beam size = 1 μm
→ Angular stability of the mirror ～ 0.1 μrad88

Alignment

Image on X‐ray CCD cameraL  2  x
x

2L
89

Image of reflected x‐ray

Alignment
1m from focal point( CCD )

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×3.8 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)
90

Alignment

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.
91

Alignment

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.
92

Alignment

Alignment of incident angle
X‐ray

X‐ray
CCD
cameraX‐ray Mirror

X‐ray

X‐ray
CCD
cameraX‐ray Mirror

93

Alignment

Foucault test
Image on CCD Projection image
Downstream

Focal plane
Knife edge

Upstream
Whole bright‐area
gradually becomes dark.

Knife edge shadow
94

Foucault test 1

Alignment

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

X‐ray

X‐ray CCD
cameraEdge shadow
Focal point↓

Knife edge

95

Foucault test 2

Alignment

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

X‐ray CCD
camera

Focal point
↓

X‐ray

Knife edge

96

Foucault test 3

Alignment

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

X‐ray

X‐ray CCD
camera

Focal point↓

Knife edge

97

Relationshipbetween incident angle and focal position

Alignment

Tolerance of the incident angle→ only a few micro‐rad

X‐ray

Incident angle→Large ⇒ Focal point → downstream
Incident angle→Small ⇒ Focal point → upstream98

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.

Focal point

Intensity
Detector
(PIN)

X‐ray

Wire

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

Intensity (arb. unit)

1.2
Wire scan profile

1.0
0.8

Differential
profile

0.6
0.4
0.2
0.0

-0.2
-200 -150 -100

-50
0
50
Position (nm)

100

150

200
99

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
TC1
slit
size
(m)
Light source size (m)

1000

100

Relationship between Beam size and Source size
1.4
10m (Experimental)
50m (Experimental)
100m (Experimental)
10m (Calculated)
50m (Calculated)
100m (Calculated)

1.0
0.8
0.6
0.4
0.2
0.0
-1000

Horizontal focusing-500

0Position (nm)

1.4
500

1000
10m (Experimental)
50m (Experimental)
100m (Experimental)
10m (Calculated)
50m (Calculated)
100m (Calculated)

1.2

Vertical focusing
Intensity (arb. units)

Intensity (arb. units)

1.2

1.0
0.8
0.6
0.4
0.2
0.0
-1000

-500

0
Position (nm)

500

1000

101

Scanning X‐ray Fluorescence Microscope: SXFM
3000

Scanning samples
Focused X‐ray

Intensity (Counts)

Cl

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: 60×50m

Ref: M. Shimura et al., “Element array by scanning X‐ray fluorescence microscopy after cis‐diamminedichloro‐platinum(II)treatment”, Cancer research 65, 4998 (2005).
102

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, 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 the tolerance of designed parameters
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

103

Key issues for the beamline design
Key issues

Design components

Which application is the most important at the BL?
Can you specify who uses the property at the BL ?

 End station( pressure, temperature,magnetic field…)
 Sample environment
 Detector, data processing … ( automation ) Photon energy, energy resolution
 Flux, flux density
The higher, the better ?
 Beam size
The smaller, the better ?
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 & applications)

What to include or not ?
What to develop or not ?

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

 Radiation shielding hutch …
 Interlock system
 Beam shutter…
Safety first !
 Absorber, FE slit
 Cooling method, cooling system
 Selection of light sources ( power, angular dist.) Electronics in hutch ( detector, controller … ) Radiation damage (cable, tube ) Contamination on optics
 Electricity, water, air, network, control
 Environments (e, vibration… )Management of the beamline construction

104

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 operated.
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‐short & high intense pulse
high stability
shot‐by‐shot diagnosis of x‐raystiming control of x‐ray pulse
synchronization with other source …
105

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 focusing mirror, alignment ),C. Morawe ( multilayer ) ESRF
S. Goto and T. Ishikawa

106

Thank you for your kind attention.

Enjoy Cheiron school
Enjoy SPring‐8
andEnjoy Japan!
107