Download Hartmann Wavefront measurement method and beamline alignment

Hartmann wavefront sensing
Beamline alignment
Guillaume Dovillaire
SOS Trieste| October 4th, 2016 | G. Dovillaire| M COM PPT 2016.01–GD
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SOS Trieste| October 4th, 2016 | G. Dovillaire| M COM PPT 2016.01–GD
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Metrology : Off-line metrology
EUREKA Eurostar project
SOS Trieste| October 4th, 2016 | G. Dovillaire| M COM PPT 2016.01–GD
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Off-line metrology
Optical head at BNL
 1.5 meter long mirrors
 50 nrad rms accuracy / 1.2mm
resolution
 HFM and VFM configuration
 mirror down to 1.5m of radius
of curvature
 2D slopes maps, height
SOS Trieste| October 4th, 2016 | G. Dovillaire| M COM PPT 2016.01–GD
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Flat mirror characterization
Mirror flipped and data flipped
Mirror shifted
SOS Trieste| October 4th, 2016 | G. Dovillaire| M COM PPT 2016.01–GD
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Flat mirror characterization
Zeiss Silicon mirror on 115mm : R=47km, slopes=0.15 µrad rms
Radii of curvature are =43.4km, 43.5km1 and 56.5km
Max difference to average is 3.6 E-06 0.8
1/m (280km)
On 90mm, differences are below 60 nrad rms
A --> B
B --> A
0.6
B --> A Offset Gantry
Slope error in µrad
0.4
0.2
0
-80
-60
-40
-20
0
20
40
60
80
-0.2
-0.4
-0.6
-0.8
-1
Mirror coordinate in mm
SOS Trieste| October 4th, 2016 | G. Dovillaire| M COM PPT 2016.01–GD
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Toroidal mirror characterization
From A to B
7.02 nm rms
From B to A and data flipped
0.45 µrad rms
1.39 nm rms
7.51 nm rms
0.46 µrad rms
0.1 µrad rms
SOS Trieste| October 4th, 2016 | G. Dovillaire| M COM PPT 2016.01–GD
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EUV wavefront sensors
The Hartmann sensor
SOS Trieste| October 4th, 2016 | G. Dovillaire| M COM PPT 2016.01–GD
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The wavefront
Geometrical approach: surface orthogonal to all rays
Flat wavefront
Collimated beam
No aberration
Diverging beam
Spherical wavefront
No aberration
Distorted wavefront
Some aberrations
Beam
SOS Trieste| October 4th, 2016 | G. Dovillaire| M COM PPT 2016.01–GD
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The wavefront
Diffraction approach: surface defined by phase = constant

 i(r)
U(r )a(r ).e
Amplitude

 (r ) 

2 (r )
Phase





In radian
In micron
In wave
SOS Trieste| October 4th, 2016 | G. Dovillaire| M COM PPT 2016.01–GD
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The wavefront : The Zernike base
SOS Trieste| October 4th, 2016 | G. Dovillaire| M COM PPT 2016.01–GD
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Hartmann wavefront sensors
Holes are small enough to create
diffraction on the CCD
Holes pitch is large enough to avoid
crosstalk
SOS Trieste| October 4th, 2016 | G. Dovillaire| M COM PPT 2016.01–GD
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Hartmann wavefront sensors : slopes integration
How calculating the wavefront knowing the slopes
?
Wave-front estimation from wave-front slope measurements
W.H. Southwell, JOSA Vol70, No 8, Août 1980
Six1, j  Six, j
2

 ix1, j   ix, j
Pitch hole
« Successive Over relaxation method »
(jm,k1)(jm,k)Err((jm,k),Pj,k)
SOS Trieste| October 4th, 2016 | G. Dovillaire| M COM PPT 2016.01–GD
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Hartmann wavefront sensors
Raw signal on
the CCD sensor
Measured intensity profile

 i(r)
U(r )a(r ).e
Measured wavefront
SOS Trieste| October 4th, 2016 | G. Dovillaire| M COM PPT 2016.01–GD
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HASO EUV
EUV
4 to 40nm
/75 rms accuracy
72x72 holes
SOS Trieste| October 4th, 2016 | G. Dovillaire| M COM PPT 2016.01–GD
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Beam lines alignment
SOS Trieste| October 4th, 2016 | G. Dovillaire| M COM PPT 2016.01–GD
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Idea 1 : I understand the wave front I measure
Astigmatism
The benders of my KB do not focus in the same plane
Coma
One of my KB bender is not optimized
My ellipsoid is not aligned
Something
I don’t know…
SOS Trieste| October 4th, 2016 | G. Dovillaire| M COM PPT 2016.01–GD
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At- alignement of a Kirkpatrick-Baez optics
FERMI : KB alignement at 32nm
FERMI : Giovanni de Ninno, Lorenzo Raimondi, LOA : Philippe Zeitoun
Best wavefront (/4 rms)
Intensity map
5.5 x 6.2
µm2
D.L.:
4.1 x 5.9 µm2
5.1 x 6.0 µm2
SOS Trieste| October 4th, 2016 | G. Dovillaire| M COM PPT 2016.01–GD
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Idea 2 : I want an automatic alignement
SLS : automatic control of a KB at 3.5 keV
SOLEIL : Mourad Idir – Pascal Mercère – Pierre Lagarde
SOS Trieste| October 4th, 2016 | G. Dovillaire| M COM PPT 2016.01–GD
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Wavefront correction in the tender X-Rays
Before correction
After correction
7.7 nm rms
30.9 nm PV
Knife Edge Scan of Horizontal X-ray beam at LUCIA
2000
Derivative of Knife Edge Data
Gauss Fit
2250
1800
1350
FWHM = 2.55 µm
900
450
Derivative of Fluorescence
Derivative of Fluorescence
2700
0.8 nm rms
4.6 nm PV
Knife Edge Scan of Vertical X-ray beam at LUCIA
Derivative of Knife Edge Data
Gauss Fit
1500
1000
FWHM = 2.40 µm
500
0
0
-450
5025
-500
5030
5035
5040
5045
5050
Horizontal Position (µm)
5055
5060
5065
-6090
-6080
-6070
-6060
Vertical Position (µm)
SOS Trieste| October 4th, 2016 | G. Dovillaire| M COM PPT 2016.01–GD
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Idea 3:
Coupling wavefront measurements
and optics simulation software
SOS Trieste| October 4th, 2016 | G. Dovillaire| M COM PPT 2016.01–GD
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Example in visible : telescope alignment
Tzec Maun Foundation
1m diameter telescope
Modified Cassegrain type
SOS Trieste| October 4th, 2016 | G. Dovillaire| M COM PPT 2016.01–GD
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The simulation tool: Zemax
Expected performances
/100 rms WFE
Diffraction limited PSF
SOS Trieste| October 4th, 2016 | G. Dovillaire| M COM PPT 2016.01–GD
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The measurment tool : HASO4 BB
Measured performances
/10 rms WFE
The coma aberration reduces the
images contrast
SOS Trieste| October 4th, 2016 | G. Dovillaire| M COM PPT 2016.01–GD
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The measurement is set in the model
The wavefront aberrations are defined by the Zernike
coefficients and included in the simulation software
SOS Trieste| October 4th, 2016 | G. Dovillaire| M COM PPT 2016.01–GD
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The optimization process
Secondary mirror position is
variable
SOS Trieste| October 4th, 2016 | G. Dovillaire| M COM PPT 2016.01–GD
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The result
The secondary mirror must be shifted and tilted to remove
the measured aberration.
Just grab the screwdriver…
SOS Trieste| October 4th, 2016 | G. Dovillaire| M COM PPT 2016.01–GD
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Conclusion
SOS Trieste| October 4th, 2016 | G. Dovillaire| M COM PPT 2016.01–GD
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SOS Trieste| October 4th, 2016 | G. Dovillaire| M COM PPT 2016.01–GD
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