Relay imaging an illuminated circular mask is a common way of projecting a laser beam onto the photocathode in an RF photo-injector whilst generating a round laser beam spot with a sharp-edged profile. The mask is illuminated with the laser beam and an optical system images the mask onto the cathode. Geometrical optics predicts the beam on the cathode will be an exact replica of the intensity...
The SASE3 soft X-ray beamline at the European XFEL is equipped with a 100-meter-long-arm monochromator, which delivers to the experiments (SQS, SCS, SXP) pink or monochromatic beam in the photon energy range of 250 eV - 3000 eV. Due to the considerable length of the arm, ensuring stability becomes crucial in the short and long timescale. Currently, the system does not have cooling installed,...
A halved polycapillary lens (PCL) may be used as an efficient collimator in the soft X-ray domain. We present recent results of laboratory-based experiments with a micron-sized fluorescence source (Carbon K$_{\alpha}$ line, 277 eV). Its emission is collected by the PCL and converted into an almost parallel beam, with a residual angular divergence less than 7 mrad. As evaluated by a CCD camera...
The advent of low-emittance X-ray sources necessitates the development of new beam diagnostic methods. Existing systems tend to provide limited information or inadequate spatial resolution. A newly-developed spatial beam property analyzer has been introduced, which comprises a double-crystal monochromator followed by a Laue crystal arranged in a dispersive diffraction configuration. Through...
An accurate characterization of the real performance sophisticated reflective or diffractive optics including such cases as XUV reflective zone plates (RZP) or multilayer coated gratings is extremely demanding task to experimental conditions. An At-Wavelength Metrology facility for EUV and XUV optics is under operation since many years at the BESSY-II storage ring. As the main instrument a...
Accurate online characterization of the intensity, spectral distribution, and temporal structure of X-ray pulses is crucial for free-electron lasers. We propose a novel approach for characterizing temporal profiles of X-ray pulses at the free-electron laser FLASH in Hamburg, using β-Variational Autoencoder (β-VAE) [1] networks in conjunction with a Transverse Deflecting Structure...
Modern synchrotron and free-electron laser sources demand ultra-high-quality x-ray mirrors for many challenging x-ray applications, including nano focusing, preserving coherence, and extreme energy resolution. As a deterministic polishing technique, Ion Beam Figuring (IBF) is often used to produce these mirrors with the required precision. Recently, an in-house IBF system has been developed...
The LCLS-II-HE beamline at SLAC (Menlo Park, USA) is planned to come online in 2027. With FEL photon energies ranging from 0.25 keV to more than 18 keV at up to 1 MHz repetition rate, the upgraded beam calls for new science endstations to be developed. The Dynamic X-ray Scattering (DXS) instrument will employ experimentation methods such as X-Ray Photon Correlation Spectroscopy (XPCS) and High...
Recent technological advances at synchrotron and free electron laser facilities, including brighter X-ray sources, faster detectors, and automated sample handling, have led to an increasing demand to tailor the X-ray beam profile to the size and shape of the sample. For beamlines which routinely measure hundreds of samples per day, such changes need to be made rapidly and autonomously. Bimorph...
Accelerator-based photon sources have improved in brilliance, stability, and coherence over the last decades. To transfer those properties to photon-hungry and high-resolution-demanding users and experiments in the VUV-, soft- and tender X-ray photon energy range, high-quality blazed profile gratings are mandatory. In addition, such gratings are of interest e.g. for spectroscopic applications...
Established in 2017, LEAPS is the League of European Accelerator-based Photon Sources, a strategic consortium initiated by the Directors of the Synchrotron Radiation and Free Electron Laser (FEL) user facilities in Europe. Its primary goal is to actively and constructively ensure and promote the quality and impact of the fundamental, applied and industrial research carried out at their...
We present a new 2D stitching method that effectively removes the systematic errors introduced by the reference flat, as well as any other additive measurement error constant across the sub-aperture measurements. This method, referred to as Linear Error Elimination Procedure (LEEP), can provide the two-dimensional error map for a wide range of X-Ray mirror lengths and figures, with...
Micropore optics (MPOs) have become the optic of choice in recent years for low mass and wide-angle field of view x-ray missions, such as SVOM and Einstein Probe. The Soft X-ray Imager (SXI) instrument for ESA’s SMILE mission aims to spectrally map the location, shape and motion of the Earth’s magnetosphere as it interacts with high energy particles excited by the Sun’s solar wind. To meet...
The ALBA Synchrotron (Barcelona, Spain) is commissioning MINERVA a new X-ray beamline designed to support the development of the NewATHENA mission (Advanced Telescope for High Energy Astrophysics), which mission is to observe and study energetic objects in space (accretion disk around black holes, large-scale structure, etc...). MINERVA is dedicated to assemble stacks manufactured by cosine...
Light beams carrying Orbital Angular Momentum (OAM) are sparking new developments in several fields like the excitation of chiral magnetic phenomena, both in the static and dynamic regime, enhanced imaging and novel light-matter interaction. The creation and characterization of OAM beams is by itself a challenging task and thus a separate field of study.
At FERMI we can create an OAM beam...
We present some of the methods, procedures and analysis tools used at ALBA to characterize mirror benders, and other adaptive optics mirror systems. The tests we describe combine measurements of different instruments, including our NOM and our stitching interferometry platform, with a number of optimization routines based on the deformation model of the mirror within the bender.
The...
SHINE is China’s first Hard X-ray FEL and now is under construction. This facility has an 8-GeV CW superconducting linac accelerator. Using 3 phase-I undulator lines, the SHINE aims at generating X-rays between 0.4 and 25 keV at rates up to 1MHz for 10 experimental stations. We have finished the design concepts of photon diagnosis for different diagnosis purposes, including Photon Arrival Time...
High precision and accurate metrology plays a pivotal role in the characterization and improvement of X-ray mirrors for synchrotron and X-ray Free Electron Laser (FEL) sources. To meet the stringent requirements of nano-precision metrology for demanding X-ray mirrors, a novel metrology instrument called Speckle Angular Metrology (SAM) has been recently developed at Diamond Light Source [1]. We...
The tender X-ray region provides access to various absorption edges, such as sulfur, chlorine, and silicon, which are of particular interest for developing organic semiconductors. Direct measurement of the X-ray spectrum in the energy region between 2.5 – 4.0 keV is challenging and typically suffers from poorer energy resolution from ruled gratings or lower efficiency from scattering-based...
At FELs, Bragg diffraction experiments are usually performed with monochromatic beam, whose bandwidth is smaller than the acceptance of the Bragg peak under investigation. This enables straightforward normalization of the measured Bragg peak intensity by detecting the FEL pulse intensity with a “scalar” detector (e.g. a diode measuring the scattering from a thin foil). In certain FEL...
We report on a fast and reliable method for wavefront sensing in the soft X-ray domain, developed for the characterization of rotationally symmetric optical elements, like an ellipsoidal mirror shell. In our laboratory setup, the mirror sample is irradiated by an electron-excited (4.4 keV), micron-sized ($\approx 2\,\mu\textrm{m}$) fluorescence source (Carbon K$_{\alpha}$, 277 eV). The...
We evaluate the damage threshold of an Au coated flat mirror, which is one of the reflective optics installed on FEL-1 beamline of Dalian Coherent Light Source (DCLS), upon far UV free electron laser (FEL) irradiation. The surface of the coating is characterized by profilometer and optical microscope. We present also theoretical approach of the phenomenon by applying conventional single-pulse...
Acquiring direct images of distant exoplanets or focusing X-rays requires high performance optics. Laboratories and optics suppliers are therefore actively seeking to improve polishing methods and metrology. For slope-error evaluation, many accelerator-based light sources use Long Trace Profilers (LTP) whose measurement accuracy can reach 80 nrad in a relatively short period of 6 hours, and...
In this work, we describe an innovative wavefront metrology technique at the first-generation synchrotron radiation source BSRF named Double Edges Scan (DES) wavefront metrology technique. It can achieve high precision measurement of the optical elements used in the fourth-generation synchrotron radiation source. The approach we proposed can resolve several vital problems of the...
We present the upgraded TRIXS (Time-Resolved Inelastic soft X-ray Scattering Spectrometer) end station at the PG1 monochromator beamline at the soft X-ray free-electron laser FLASH [1]. TRIXS was developed for studies of ultrafast processes in condensed matter, e. g. various types of interactions in strongly correlated electronic systems, by means of femtosecond pump-probe IXS technique with...
We report on the latest developments regarding the design and initial operations of the Molecular and Optical Science Technology beamline (MOST), the new beamline specifically devoted to serve the atomic and molecular physics community at Elettra 2.0.
Two new insertion devices (IDs) have recently been installed, adopting an in-line configuration; one covers the low-to-intermediate photon...
X-ray wavefront provides precise information about optics misalignments, optics figure errors, and beam caustics. The knife edge wavefront sensing method is developed recently at Diamond Light Source and used in the wavefront profile reconstruction of focusing elements such as X-ray mirrors and lenses [1]. The wavefront profile is reconstructed from the intensity drop in each pixel of an area...
The performance of reflective optics such as X-ray mirrors or diffraction gratings generally degrades following exposure to high intensity X-ray or EUV beams. The most common degradation phenomenon is beam-induced contamination with the formation of inhomogeneous carbonaceous films on the optical surface.
Most X-ray light sources suffer from these effects which progressively reduce the...
With the reduction of the emittance of electron bunches in new generation synchrotron radiation sources, the generated X-ray beam is beneficial for applications with high spatial resolution, coherence, and flux, bringing opportunities for the design of multifunctional beamlines. Considering the partial coherent characteristics of the light field, the achievement of experiments requiring flux...
