Dr Jaromír Chalupský, deputy head of the Department of Radiation and Chemical Physics (Institute of Physics of the Czech Academy of Sciences in Prague), has been awarded the FELs of Europe Award on Photon Transport and Diagnostics 2018 for an excellent contribution to the photon diagnostics of free-electron lasers, the guidance, characterisation and adjustment of laser beams and to the FEL instrumentation in general.
The award reflects namely Dr Chalupský’s insight into the fundamental problem of the characterisation of XUV/X-ray laser beams in a focus and its vicinity. As a result of very high intensities and beam parameters fluctuation from shot to shot, conventional methods which worked well for example in the characterisation of synchrotron radiation beams cannot be applied successfully. Already more than a decade ago, Dr Jaromír Chalupský recognized and used the potential of ablation imprint methods for this purpose. He managed to develop these methods in such an extent that he went far beyond the initial goal of the precise and reliable determination of the area of beams in a focus.
In his work, Dr Chalupský extended the applicability of the mentioned methods by the characterisation of non-Gausian beams. This is really important as the beams of short-wavelength lasers, namely of those working in the SASE (Self Amplified Spontaneous Emission) mode, are rarely Gausian. For this purpose, he developed and applied a method of a laser beam fluence scan (f-scan). This method enables to reconstruct the intensity distribution in a beam only from its ablation contours created at different areal energy densities (fluences). Using suitable optical instruments, an FEL beam can be diagnosed directly in a vacuum interaction chamber without the need to aerate it and to take the illuminated sample out for an ex situ analysis. This brings a significant saving of the operating time of the extremely busy FEL sources.
Dr Chalupský has also developed and applied a specific z-scan technique for the determination of the longitudinal intensity distribution in the focused XUV/x-ray laser beams. Apart from ablation, he also used induced short-wavelength lasers for imprints and material desorption. He then further develop the ablation and desorption imprint technique to such a level which enabled him to acquire information about phase and coherence properties of FEL radiation. In addition, Dr Chalupský has developed a number of theoretical concepts and procedures providing a more detailed and precise picture of the processes occurring during the interaction of highly intensive XUV/x-ray radiation with the matter.
This year, the award was presented at the international PhotonDiag 2018 – Workshop on FEL Photon Diagnostics, Instrumentation and Beamlines Design held in Hamburg, 17-19 September 2018. This workshop, the fourth so far, was jointly organised by the FELs of Europe Collaboration, DESY Photon Science and European XFEL. Apart from a diploma, the award winner receives also a sum of 1000 EUR and an opportunity to give a lecture on the results of the award-winning research. Dr Jaromír Chalupský is only the second winner of the award in its history.
In 2017, the first award went to Dr Diling Zhu, a staff scientist in the Hard X-ray Department at the Linac Coherent Light Source (LCLS) in the Stanford Linear Accelerator Center (SLAC), Menlo Park, CA, for his crucial contribution to the development of new hard x-ray FEL tools and techniques, such as thin crystal multiplexing, a crystal-based split-and-delay units, and schemes and tools for precise timing of FEL impulses and a thin-crystal single shot spectrometer for LCLS.
For more details on the award-winning methods and results, see:
1. J. Chalupský at al.: Characteristics of focused soft X-ray free-electron laser beam determined by ablation of organic molecular solids, Opt. Express 15, 6036 (2007).
2. J. Chalupský at al.: Non-thermal desorption/ablation of molecular solids induced by ultra-short soft x-ray pulses, Opt. Express 17, 208 (2009).
3. J. Chalupský at al.: Spot size characterization of focused non-Gaussian X-ray laser beams, Opt. Express 18, 27836 (2010).
4. J. Chalupský at al.: Fluence scan: unexplored property of a laser beam, Opt. Express 21, 26363 (2013).
5. J. Chalupský at al.: Imprinting a focused X-ray laser beam to measure its full spatial characteristics, Phys. Rev. Appl. 4, 014004 (2015).