Download presentation
Presentation is loading. Please wait.
1
Coherence measurements at P04
Petr Skopintsev P04 Users Meeting, DESY, Hamburg, Germany NRC “Kurchatov Institute”, Moscow, Russia Collaboration between: Jens Viefhaus (P04 – Beam line) Axel Rosenhahn (Analytical Chemistry Group, Ruhr-University Bochum) Ivan Vartanyants (Coherent Imaging Group)
2
Theory of spatial coherence measurements
Outline Theory of spatial coherence measurements First P04 experiment Comparison of NRAs and Double Pinholes Second P04 experiment Additional investigation with NRAs Summary
3
Intensity Сoherence Factor
Time domain removed for simplicity Spatial coherence Intensity Сoherence Factor Incoherent field Coherent field
4
intensity distribution I(q)
Young’s Experiment Incoherent Coherent Part. coherent Double pinholes diffraction intensity distribution I(q) Fourier transform of I(q)
5
Young’s Experiment Δx -Δx Δx J.W. Goodman, Statistical optics
6
Young’s Experiment Δx -Δx Δx J.W. Goodman, Statistical optics
7
Non-Redundant Array of Slits
10 peaks 10 points 1 experiment with 5 slits = 10 experiments with 2 slits
8
P04 beamline (PETRA III) experiment
Undulator tuned to 400 eV B Exit slit openings: 40 µm and 230 µm * Vacuum chamber constructed by Hans Peter Oepen group (Hamburg University)
9
Data: Typical Intensity Scans
NRA NRA Double pinholes Detector plane Fourier Transform
10
Data: Typical Intensity Scans
2R R NRA NRA Second harmonics (monochromator) 800 eV 2R Double pinholes 400 eV R 400 eV 800 eV Detector plane Fourier Transform
11
Data: Typical Intensity Scans
NRA NRA Second harmonics (monochromator) 800 eV Double pinholes 400 eV 400 eV 800 eV Detector plane Fourier Transform
12
Data: Typical Intensity Scans
NRA Detector plane Fourier Transform Double pinholes
13
Data: Beam Profile Scans
Performed on double pinholes separated by 15 µm FWHM found with double Gauss functions fits Exit slit 40 µm Exit slit 230 µm
14
Results: NRA & D.P. are identical
E = 400 eV Double pinholes data points NRA data points Exit Slit width 40 µm Exit Slit width 230 µm
15
D C P04 beamline experiment Beam defining slit opening varied
Exit slit cut out 396.5, 400 and 403 eV fraction of the beam * Vacuum chamber constructed by Hans Peter Oepen group (Hamburg University)
16
Beam defining slit variation
E = eV, 400 eV, 403 eV Exit Slit width 230 µm Features of coherence dependence on beam defining slit opening observed
17
Aim – measure spatial coherence prior to ptychography experiment
Second experiment at P04 Aim – measure spatial coherence prior to ptychography experiment
18
Second experiment at P04 Undulator energy Exit slit opening
NRA orientation 1. 50 μm μm μm a. Horizontal b. Vertical 500 eV * HORST chamber constructed by Axel Rosenhahn group (Ruhr-University Bochum)
19
P04 diffraction patterns
How can we achieve nm-scale resolution? Why phase images are of interest? P04 diffraction patterns Typical diffraction image Fourier transform Area for further analysis
20
50 μm 100 μm 200 μm P04 Vertical coherence profile Beam Coherence
Exit slit: 50 μm 100 μm 200 μm FWHM = 7 μm FWHM = 12.6 μm FWHM = 29.5 μm lc = 7.5 μm lc = 4.2 μm lc = 2.4 μm ζ = 0.73 ζ = 0.37 ζ = 0.10 profile Beam Coherence
21
P04 Horizontal coherence
Exit slit: 50 μm 100 μm 200 μm lc = 12.5 μm lc = 12.4 μm lc = 12.4 μm ζ = 0.14 ζ = 0.14 ζ = 0.15 Coherence FWHM estimated as 100 μm
22
PETRA III vs BESSY II
23
Conclusions NRA allows to measure full spatial coherence function in one exposure Results with NRAs and double pinholes are identical NRA method works especially well with large beams This approach can be effectively used prior to any coherent imaging experiment May be useful for measuring single pulse coherence properties of FELs
24
J. Viefhaus Thank you for your attention! Thanks to DESY: A. Singer
O.Y. Gorobtsov D. Dzhigaev A. Shabalin O.M. Yefanov M. Rose R.P. Kurta I.A. Vartanyants SLAC: A. Sakdinawat J. Viefhaus DESY: L. Glaser L. Müller S. Schleitzer G. Grübel Uni. Hamburg: J. Bach B. Beyersdorff R. Frömter H.P. Oepen Bochum: T. Senkbeil A. Buck T. Gorniak A. Rosenhahn Thank you for your attention!
26
S1. Temporal coherence
27
S2. Two-dimensional NRA Image taken from Gonzalez, A. I. & Meja, Y. (2011). J. Opt. Soc. Am. A, 28(6),
28
S3. Non-uniformity of coherence
15 7.5 -7.5 -15 -15 -7.5 7.5 15 -15 -7.5 7.5 15
29
S3. Non-uniformity of coherence
15 7.5 100 μm -7.5 -15 200 μm -15 -7.5 7.5 15
30
S4. More data on coherence
Energy: 396.5 eV 400 eV 403 eV
Similar presentations
