Imperfection in X-ray focusing optical elements result in phase errors which when propagated to the focal plane cause broadening of the focused beam profile. A useful concept is the X-ray wavefront which is a surface of constant phase and for ideal focusing this is a spherical surface centred on the focal point. Aberrations in optical elements cause a deviation of the wavefront from this ideal...
Blazed gratings are an essential element for instruments used at free electron laser and synchrotron facilities in soft and tender X-ray ranges. Their application ranges from beamline monochromators and spectrometer analyzers to self-seeding and pulse compression elements. These gratings are commonly made by mechanical ruling, however, the production time of high-quality blazed gratings has...
The XRD2 and XPRESS beamlines of Elettra, the Italian synchrotron facility, share a multipole semiconducting wiggler as photon source. XRD2 receives light from the central portion of the photon beam while a Si(111) beam splitter, at an incident angle of 4.5°, reflects a side portion of the radiation cone towards XPRESS. Upon dismounting, the crystal showed an unexpected, longitudinal, 4...
We present the Diamond-VeNOM (velocity-NOM): a high-speed slope profiler of X-ray optics. With recent improvements in the fabrication quality of X-ray mirrors, the systematic errors of optical profilers are no longer negligible. For optics with slope errors << 100 nrad rms, repeated scans with the mirror oriented in a range of configurations are required to null experimental errors and improve...
In the past 5 years, the LCLS Optics Metrology Laboratory has measured and encountered numerous types of extreme x-ray optics in various phases, i.e. from prototyping to qualifying the bare optics to the fully assembled optics systems. In this presentation, selected examples of optic work will be shared for illustrating the interesting experience working with optics for the LCLS, and the...
For new astrophysics X-ray observatories like the Advanced Telescope for High ENergy Astrophysics (ATHENA), mirror surfaces of several hundred m² are required. As such an area is not achievable with a single mirror in space, the silicon pore optics (SPO) technology will be utilized. In the PTB laboratory at BESSY II, two dedicated beamlines are in use for their characterization with...
In most synchrotron applications, X-ray mirror slope specification is an important parameter for applications using a partially coherent X-ray beam. The slope error is typically specified at the sub 100 nrad RMS for mirrors up to 1000 mm long by 50 mm wide. For applications using diffraction-limited X-ray beams, height specification is a more relevant parameter to maintain and focus the beam...
Multilayer coating on top of high line density blazed gratings can increase its diffraction efficiency up to one order of magnitude for a selected diffraction order. In combination with multilayer coated pre-mirror in plane grating monochromator (PGM) the total instrument transmission can be increased in hundreds of times. In our developments on multilayer-coated blazed gratings (MLBG) we have...
Driven by the fast development of the new generation storage ring and free-electron laser facilities, X-ray mirrors with nanometer figure accuracy, complex shape and large size are widely demanded. These optics are being developed in Tongji University using stitching interferometry and ion beam figuring technique. Stitching interferometry is commonly used for the 2-D figure metrology of X-ray...
SwissFEL is a free electron laser, comprising of two undulator lines with three endstations each: covering 2 – 12.7 keV (up to 1.5 mJ) and 0.25 – 2 keV (up to 5.0 mJ), respectively.
We present the design and commissioning of the ATHOS soft x-ray optics, starting with the overall beamline-layout and the optical components inside the front-end: a gas attenuator, a thin foil based solid-state...
BEaTriX (Beam Expander Testing X-ray) is a unique facility developed at the INAF-Osservatorio Astronomico Brera (Merate, Italy) to test ATHENA’s X-ray mirror. The commissioning has been successfully completed, and the facility is now open to users.
The unique BEaTriX X-ray beam approximates the one created by an astronomical source (collimated and large), and it is re-created in a small lab...
State-of-the-art soft X-ray beamlines use collimated plan-grating monochromators (cPGM) as monochromatizing devices. Multi-Layer (ML) coated plane gratings and mirrors allow to extend the available photon energy range of cPGM’s towards the so-called tender X-ray photon energy range (up to 5 keV) providing a significantly higher photon flux. This X-ray energy regime covers L- and M-absorption...
The scattering properties of mirror surfaces are strongly dependent on the surface structure and radiation incidence angle, for a given photon energy. In particular, in Free Electron Laser and Synchrotron X-ray photon transport beamlines, the perturbation of the scattering effect is often dominant in the Point Spread Function (PSF) degradation. The perturbation theory explains the surface...
Varied-line-spacing grating is a key optical element in the light facilities, concerning lithography, holography, tomography, as well as spatially resolved monochromator/spectrometer. In the last decades, the grooves parameters of varied-line-spacing gratings are necessary to be strictly deduced through the light path function and the Fermat's principle. This method is of great importance to...
The race toward completing several next-generation X-ray light source facilities around the world has been running hot since a few years. This has created the need to accurately simulate the performances of the beamlines before they are built, so as to make sure the optimal layout has been chosen. To this end, the optical community has at its disposal several simulation tools, most of them...
The monochromatization of radiation in the extreme ultraviolet spectral region is accomplished by using diffraction gratings at grazing incidence. In the most general case, the grating is roto-translated to perform the wavelength scanning. Different optical configurations have been proposed until now, both using plane and concave gratings and with uniform or variable line spacing.
In this...
We present two significant projects, namely OASYS (OrAnge SYnchrotron Suite)
and DABAM (DAta BAse for mirror Metrology), which emerged as notable outcomes from MEADOW2013. Both projects have had a considerable impact on the field of X-ray science and have provided valuable resources for researchers and scientists.
OASYS [1], an open-source software suite developed for the simulation and...
Extreme ultraviolet lithography (EUVL) is considered to be the future method of mass production of integrated circuits on chips. For long time, Free-Electron Lasers (FELs) have been proposed to accomplish the challenges of EUVL, i.e., a suitable power optical light source and the scanning speed of the wafer. According to this, we developed a two-steps EUVL experiment at FLASH using a...
For the past 10 years, wavefront sensing has been a crucial component of Free Electron Laser (FEL) facilities. Not only does it help evaluate the quality of the wavefront delivered on the sample and optimize optical systems, but it also opens the door to the new, intriguing field of source metrology. Because of the complexity of the emission process, important parameters such as the effective...
Proper in-situ fine-adjustment of the optical elements is crucial for an optimal performance of beam lines at synchrotron or free-electron laser facilities, considering that even slight misalignments of the grazing incidence mirrors can already deteriorate the focal spot. Real-time wavefront monitoring represents a valuable tool for reduction of these aberrations. In particular, wavefront...
The intense X-ray FEL beam delivered by European X-ray Free Electron Laser (EuXFEL) facility gives rise to strong challenges for the optics and their diagnostic. It is important to have an accurate knowledge of the single pulse X-ray wavefront, which affects focal plane intensity and profile, spot size, and spatial resolution, as well as centroid location within the focal plane. Wavefront...
Wavefront sensing is a powerful tool enabling a variety of applications ranging from characterization and alignment of passive or active optical systems to non-destructive testing and phase imaging. Indeed, in the recent past, high-resolution Hartmann sensors have facilitated translating the applications of wavefront sensing to the extreme ultraviolet and X-ray spectral range.
In this...
Over the last decade, X-ray speckle-based techniques have been extensively developed for advanced imaging and high precision metrology of X-ray optics. The speckle-based techniques have gained popularity due to their relatively simple experimental requirements and ease of use. At Diamond, we have worked extensively since 2012 to enhance the technique and to apply it to a range of X-ray imaging...
The Advanced Photon Source (APS) has achieved significant advancements in X-ray wavefront sensing and at-wavelength metrology, which are essential for optimizing the performance of X-ray optics and synchrotron beamlines. A notable breakthrough is the development of the coded-mask-based wavefront sensing technique, which merges the advantages of grating interferometry and speckle tracking....
In recent years, several x-ray facilities have begun to use multilayer gratings (MLGs) in plane-grating monochromators thanks to their vastly superior efficiencies in the tender x-ray range compared to traditional single-layer gratings (SLGs). However, most of the software tools normally used for simulating the efficiencies of SLGs are not able to simulate MLGs. As a result several x-ray...
In order to aid the design and development of optical elements, such as Reflection Zone Plates, and automate the process of aligning optics in both spectrometers and beamlines, we have developed new simulation software as well as deep learning AI methods.
RAY-X, our open-source state-of-the-art physics-based ray tracing software is designed to utilise modern GPUs to reduce trace time of...
A new computer program has been created to assist in radiation safety ray trace operation for Linac Coherent Light Source (LCLS) at SLAC National Accelerator Laboratory. In contrast to historical method which has been performed manually using drafting tools on CAD softwares, the computer-based calculation propagate the illumination boundaries automatically and accurately using phase space...
We have developed a sub-10 nm focusing system to achieve an ultraintense X-ray laser field with 10^22 W/cm^2 intensity at SACLA. For the sub-10 nm focusing optics, an advanced KB (AKB) mirror system based on Wolter-type III geometry has been adopted. One of the remarkable challenges was the fabrication of steeply curved mirrors with radii of curvature of ~3 m with a shape accuracy of 1 nm. We...
X-ray Gas Monitors (XGMs) are operated at European XFEL for non-invasive single-shot pulse energy measurements and average beam position monitoring. The basic mechanism is photo-ionization of rare gas atoms. They are used for machine SASE tuning and for sorting single-shot experimental data according to the pulse energy. The XGMs were developed at DESY based on the specific requirements of...
The Pohang Accelerator Laboratory X-ray Free-Electron Laser (PAL-XFEL) operates hard X-ray and soft X-ray beamlines for scientific experiments with providing intense ultrashort X-ray pulses based on the self-amplified spontaneous emission (SASE) process. X-ray Free-Electron Laser is characterized by strong pulse-to-pulse fluctuations due to the SASE process. Thus, online photon diagnostics are...
In this work, the performances of thin (0.5um-10um) Silicon Carbide (SiC) membranes as in-line X-ray Beam Position Monitors (XBPM) for synchrotron beams presented and compared with commercial single- and poly-crystalline diamond ones. Results show that SiC devices can reach superior transparencies with respect to diamond, thanks to the realisation of <2um thick sensors, while allowing for much...
When dealing with experiments conducted at 4th-generation synchrotron radiation and free electron laser beamlines, the primary challenge for X-ray optical elements lies in achieving and maintaining focused X-ray beams of high intensity, possessing near-perfect wavefront quality and exceptional stability. Optical elements necessitate more stringent specifications compared to other applications...
Non-destructive, single-shot recording of longitudinal bunch profiles is a prerequisite for accelerator commissioning and operation. A common strategy for the measurement of ultra-short electron bunches is to sample the Coulomb field with femtosecond laser pulses. However, recording electric field evolution in single-shot with THz bandwidth is a largely open problem and has been recognized as...
Controlling optical properties with nonlinear light-matter interactions, which has been the justification of optical lasers, remains largely unexplored in the hard X-ray region. By combining nanofocusing optics and stable X-ray pulses from SACLA, we are testing various concepts of nonlinear devices to control the temporal and spectral properties of XFEL pulses. In this talk, I will discuss our...
FLASH, the free-electron laser in Hamburg, operates in the self-amplified spontaneous emission (SASE) regime, leading to a unique combination of energy, spectrum, arrival time and pulse duration. So it is critical to be able to determine the pulse duration and arrival time of each pulse. THz field-driven streaking has the potential to deliver single-shot pulse duration information basically...
The European X-ray Free Electron Laser (XFEL) facility produces extremely intense and short X-ray pulses, where the diagnostics of the X-ray beam properties is of critical importance. Besides existing diagnostic components, utilization of a diamond sensor was proposed to achieve radiation hard, non-invasive beam position and pulse energy measurements for hard X-rays. In particular, at very...
Developments of cutting-edge X-ray detectors are largely driven by experiments at large photon science facilities, i.e. the synchrotron radiation sources and free-electron lasers (FELs) which enable a wealth of investigations in different subjects. At PSI, we develop hybrid X-ray detectors for these facilities as well as for the next-generation radiation sources, namely diffraction-limited...
Hard X-ray imaging techniques employing bright-field images, such as bright-field microscopy and in-line holography, offer the benefit of capturing a wide field of view without the need to scan the sample. However, the spatial resolution of these techniques has been limited by the numerical aperture (NA) of hard X-ray optics.
Advanced KB optics based on Wolter type-III geometry is highly...
The impact from optics on circular, elliptical, and inclined linear polarized light at synchrotron beamlines is known and understood but perhaps not always addressed. This impact is of particular interest for beamlines operating below ~150 eV and it becomes severe for energies below 40-60 eV, depending on the beamline’s optical layout. The Bloch beamline at MAXIV Laboratory is designed for...
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...
