Wir schaffen Wissen heute für morgen

Transcription

1 Analyzing Wavefront and Spectrum of Hard X-ray Free-Electron Laser Radiation SLS (since 2001) Wir schaffen Wissen heute für morgen PSI: SLAC: SACLA: EuroXFEL: C. David, S. Rutishauser, P. Karvinen, I. Vartiainen, A. Diaz, M. Guizar-Sicairos, I. Mohacsi, Y. Kayser, U. Flechsig, P. Juranic, L. Patthey, A. Mozzanica, M. Makita J. Krzywinski, M. Cammarata, D.M. Fritz, T.H. Lemke, D. Zhu Y. Feng, S. Song, M. Sikorski, T. Katayama, M. Yabashi L. Samoylova, J. Grünert, H. Sinn PSI,

2 Analyzing Wavefront and Spectrum of Hard X-ray Free-Electron Laser Radiation PSI: SLAC: SACLA: EuroXFEL: Mission: To develop novel instrumentation for Large Scale Facilities at PSI and elsewhere by applying advanced micro- and nanotechnology C. David, S. Rutishauser, P. Karvinen, I. Vartiainen, A. Diaz, M. Guizar-Sicairos, Y. Kayser, U. Flechsig, P. Juranic, L. Patthey, A. Mozzanica, M. Makita Wir schaffen Wissen heute für morgen J. Krzywinski, M. Cammarata, D.M. Fritz, T.H. Lemke, D. Zhu Y. Feng, S. Song, M. Sikorski, T. Katayama, M. Yabashi L. Samoylova, J. Grünert, H. Sinn PSI,

3 High performance Fresnel zone plates 500 nm FIB cross-section of 25nm wide, 550nm high Ir zone plate Very high resolution & good efficiency: - 4.2% at 9 kev photon energy for 25nm zone width K. Jefimovs et al. Phys. Rev. Lett. 99 (2007) ; J. Vila-Comamala et al., Ultramicroscopy 109 (2009) p J. Vila-Comamala et al., Nanotechnology 21 (2010) ; J. Vila-Comamala et al., Optics Express 19 (2011) 175

4 High performance Fresnel zone plates FIB cross-section of a 25nm wide, 1100nm high double sided Ir zone plate Very high resolution & very high efficiency: - 9.9% at 9 kev photon energy for 25nm zone width I. Mohacsi et al., Double-sided diffractive X-ray optics for hard X-ray microscopy, Optics Express, 23 (2015) p. 776

5 High performance Fresnel zone plates Spot of a 15nm zone plate reconstructed by ptychography: FWHM: 15.0 nm Efficiency is low: < 1% at 9 kev.! Interlaced double-sided line-doubled zone plate with 4x reduced zone width Patent application: US by Carl Zeiss X-Ray Microscopy Inc. Spot of a 7nm zone plate reconstructed by ptychography: FWHM: 7.1 nm I. Mohacsi et al., Double-Sided Fresnel Zone Plates, presented at the XRM2014, Melbourne

6 SASE emission of X-ray Free-Electron Laser Radiation Self-amplified spontaneous emission (SASE): Relativistic electrons in a long undulator generate x-rays Electrons interact with x-ray field and form bunches Exponential amplification of emission with increasing undulator length (gain) Instability of emission process leads to stochastic fluctuations of emission pulses Each pulse is different! Taken from: B. W. J. McNeil and N. R. Thompson, Nature Photonics 4, 814 (2010)

7 Calculated SASE emission of the European XFEL at 12keV Temporal structure Spectrum Taken from: G. Geloni et al., New J. Phys. 12 (2010)

8 Hard XFEL wave front characterization using X-ray grating interferometry Was initially developed for phase contrast imaging Phase gradients are converted into intensity changes using a set of two gratings Grating based interferometry detects small refraction angles introduced by the object => Measures local changes in the x-ray wave front phase object beam-splitter phase grating interference pattern analyzer amplitude grating Differential phase contrast imaging camera C. David, SwissFEL Coordination Committee Meeting, May 14, 2013

9 X-ray grating interferometry beam splitter grating G 1 h=22 µm phase object beam-splitter phase grating analyzer amplitude grating p 1 =4 µm camera interference pattern h=12 µm analyzer grating G 2 p 2 =2 µm C. David, SwissFEL Coordination Committee Meeting, May 14, 2013

10 Grating-based x-ray phase contrast imaging Rat heart in formalin solution, ESRF, ID19, 17.8 kev mm 5mm 3 Absorption Phase gradient [mrad/µm] Phase [rad] 5mm Integration

11 Grating-based x-ray phase contrast imaging absorption phase Radiography of a small fish (E=17.5 kev) 3-grating setup requires no spatial coherence Standard x-ray tubes can be used for phase contrast imaging Applications in medical imaging, non-destructive testing, homeland security, Patented by PSI - licenced to Bruker-Skyscan absorption phase Slice through tomographic data set of an infant hand (E=28 kev) F. Pfeiffer, T. Weitkamp, O. Bunk, C. David, Nature Physics 2 (2006) 258, T. Donath et al. Investigative Radiology 45 (2010) 445

12 Moire method A intentional rotational misalignment of the gratings causes Moiré fringes Fringes have much bigger period and can be easily detected Any distortion of the interference fringes will distort the Moiré fringes Density of fringes can be chosen to provide best tradeoff between sensitivity and spatial resolution Allows for wavefront analysis from a single image! C. David, SwissFEL Coordination Committee Meeting, May 14, 2013

13 Wave front analysis at LCLS-XPP (E=8 kev) C. David, SwissFEL Coordination Committee Meeting, May 14, 2013

14 Wave front analysis at LCLS-XPP (E=8 kev) Goals: Single-shot investigation of source point stability Effects of machine parameters (e.g. driving laser into saturation) Single-shot measurements of the wave front aberrations caused by optical components I. Zanette, et al., T. Weitkamp, T. Donath, S. Rutishauser, and C. David, Physical Review Letters 105 (2010) p C. David, SwissFEL Coordination Committee Meeting, May 14, 2013

15 Wave front analysis at LCLS-XPP (E=8 kev) Goals: Single-shot investigation of source point stability CCD G2 on rotation stage scintillator Effects of machine parameters (e.g. driving laser into saturation) G1 on piezo actuator Single-shot measurements of the wave front aberrations caused by optical components C. David, SwissFEL Coordination Committee Meeting, May 14, 2013

16 Wave front analysis at LCLS-XPP (E=8 kev) Goals: Single-shot investigation of source point stability Effects of machine parameters (e.g. driving laser into saturation) Single-shot measurements of the wave front aberrations caused by optical components Field of view 1mm x 1mm C. David, SwissFEL Coordination Committee Meeting, May 14, 2013

17 Wave front analysis at LCLS-XPP (E=8 kev) data analysis by S. Rutishauser Simultaneous measurement of amplitude and phase allows for back-propagation to mirror plane C. David, XNPIG Workshop, Tokyo, March 5, 2012

18 Wave front analysis at LCLS-XPP (E=8 kev) individual shots 50 shots average height profile of combined mirrors LTP profile Field of view 1mm x 1mm C. David, SwissFEL Coordination Committee Meeting, May 14, 2013

19 Wave front analysis at LCLS-XPP (E=8 kev) individual shots 50 shots average height profile of combined mirrors aspheric component only LTP profile Collimating effect of HOMS: 30 nm shape error Aspheric component of mirror profile: 5 nm, matches LTP In-situ, single-shot metrology with angular sensitivity down to 10 nrad Field of view 1mm x 1mm

20 Wave front analysis at SACLA with T. Katayama, M. Yabashi, H. Ohashi, S. Rutishauser, Y. Kayser, U. Flechsig Beamline optics at SACLA for E > 7.5 kev. The beam is deflected in vertical direction. (from H. Ohashi et al., NIMA 2012) 0.7 nm Figure error of J-TEC mirror M2a measured ex-situ with stitching interferometry Y. Kayser et al., Optics Express 22 (2014) p. 9004

21 Wave front analysis at SACLA photon energy: 12.4 kev mirror profile individual shots flat region curved region 10 shot average 0.8 nm peak-to-valley 10 shot average Y. Kayser et al., Optics Express 22 (2014) p. 9004

22 Non-invasive beam splitting 0.5 mm main XFEL beam Beam splitter grating

23 focusing grating = off-axis zone plate Single-shot grating spectrometer w= 500 µm d= 2.5 m 0.5 mm XFEL beam, λ=2å focusing diamond grating, p=150 nm 3rd diffraction order, η<0.1% s detector Diffraction angle: Separation: Diffraction limit of spectral resolution (equal to number of lines x diffraction order): α = λ/p = 4 mrad s = d x α = 10 mm λ/δλ = => δe = 0.6 ev Detector: GOTTHARD strip detector, 50 µm pitch P. Karvinen et al., Single-shot analysis of hard X-ray laser radiation using a non-invasive grating spectrometer, Optics Letters 37 (2012) p. 5073

24 Single-shot grating spectrometer P. Karvinen et al. Optics Letters 37 (2012) Diamond grating with p=150 nm etched into a 5 µm thick diamond membrane C. David, SwissFEL Photonics Diagnostics Review, March 6, 2013

25 Single-shot grating spectrometer P. Karvinen et al. Optics Letters 37 (2012) undiffracted beam focusing diamond diffraction grating detector 1.2 ev Spectral resolution of 1.2 ev (close to diffraction limit) Simple, robust, radiation-hard, Problem 1: Focal length of grating changes proportional to photon energy. => need to move components over large distances to cover wide range Problem 2: Detector resolution degrades at higher energies under shallow incidence C. David, SwissFEL Photonics Diagnostics Review, March 6, 2013

26 Single shot spectral monitor of LCLS detector E min E max Bragg reflection θ min thin bent Si <111> crystal undiffracted beam s θ max r Alternative: Spectrometer based on thin, bent Si crystal analyzer (developed by LCLS) Simple Spectral resolution down to < kev!!! Problem 1: High absorption losses (up to 50%) Problem 2: thin crystals tend to oscillate D. Zhu et al., APL 101 (2012)

27 Best of both worlds detector Bragg reflection undiffracted beam undiffracted beam focusing diamond diffraction grating detector thin bent Si <111> crystal Combined solution of beam splitter grating and analyzer crystal provides: diamond beam splitter grating undiffracted beam high resolution (E/δE > ) high transmission (T>90%) stability & radiation hardness

28 Shot-to-shot spectral analysis of X-FEL radiation detector detector Tested at LCLS in collaboration with SwissFEL and SLAC Excellent resolution: ev Diamond grating bent Si <333> analyzer crystal bent Si <220> analyzer crystal Excellent agreement of split-beam and direct-beam arrangements Single-shot spectrometer (SSS) planned for SwissFEL blue: Si <333> red: Si <220> Energy [ev] Comparison of <333> and <220> spectrometer

29 Effect of pulse length on SASE spectrum 10 fs pulse length 30 fs pulse length

30 Summary We work on the micro- and nanofabrication of state-of-the-art diffractive x-ray optics Grating based x-ray interferometry can provide shot-to-shot analysis of hard XFEL wavefront The wavefront provides in-situ, at wavelength information on the distortion of XFEL optics with extreme ( 10 nrad) angular sensitivity Diffractive diamond gratings in combination with thin bent crystals - can be used for non-invasive shot-to-shot monitoring of XFEL spectra