This PDF file contains the front matter associated with SPIE Proceedings Volume 12695, including the Title Page, Copyright information, Table of Contents, and Conference Committee information.

Improvements in the quality of synchrotron beamline x-ray optics required for next-generation light sources (e.g. the ALS Upgrade project) drive the need to improve the performance of the metrology instrumentation used to measure these components. The Long Trace Profiler (LTP) that is in use at many synchrotron metrology laboratories around the world has some known issues that affect the accuracy of its measurements. The main error source is optical path difference (OPD) phase error introduced into the probe beam by inhomogeneities in the glass components used in the optical head. We have developed a new optical head design, LTP-2020, that replaces the cube polarizing beamsplitter (PBS) with a thin wedge plate polarizing beamsplitter (WPBS) and replaces the cemented doublet lens with an aspheric singlet. Both of these components significantly reduce the glass volume traversed by the laser probe beam. Careful attention to ghost ray interference produced by back reflection from optical surfaces is necessary to minimize distortion in the primary image that translates into systematic error in the slope angle measurement. We make extensive use of a commercial raytracing program to model the back reflections and adjust component parameters as necessary to minimize distortion. Deliberate misalignment of components is necessary to make the system perform correctly. Stringent requirements are placed on the 45° incidence coatings on the WPBS and on the normal incidence coatings on the lens and camera window elements. We encourage our colleagues who wish to upgrade their current LTP systems to join us in the procurement of these custom optical components.

Wolter mirrors for x-ray telescopes is fabricated through nickel electroforming process. Although the sufficient imaging ability has been confirmed through both x-ray focusing experiments and ray-trace analysis, there are still surface figure errors that need to be removed to improve the resolving power. We propose a new figure correction method combining Si coating on the mirror surface and Si removal processing. To implement this method, we have developed an inner surface profile measurement system. This system involves three non-contact laser probes that are scanned by a motorized stage. Two of the probes are used for compensating motion errors of the scanning stage. This method enables us to measure a one-dimensional figure error profile of the Wolter mirrors with a reproducibility on the order of single nanometers.

We present a two-carriage, air-bearing system on a common ceramic support beam designed to utilize multiple modes of long-trace-profiler (LTP) operation, with movable and stationary optical sensors for both coherent and incoherent light probes, dubbed the LTP-2020. Measurements with different movable and stationary sensors integrated in the LTP-2020 system allow on-bench round-robin comparisons for ensuring high-accuracy metrology of x-ray optics. In the case of variable-line-spacing (VLS) gratings, one sensor can characterize the zero-order surface, and the second, in Littrow configuration, can record diffraction angle changes without introducing uncertainty of the mutual alignment between tools. We also aspire to preserve the major advantage of the current ALS LTP-II with the capability of raising and lowering the ceramic beam with the carriages and sensors. This design allows characterization of unmounted optical substrates, as well as multi-element optical systems and large mirror assemblies, such as bendable x-ray mirrors. The modular design of the LTP-2020 gantry system together with reconfigurable optical sensors mounted to separate carriages allows operation for scanning optical surfaces at three native orientations: face-up, side-facing, face-down. We also discuss the gantry system motion control algorithms and software that enable us to perform sophisticated data acquisition based on advanced optimal scanning strategies for anti-correlation of temporal drift and systematic errors. Experimental data illustrating the high performance of the developed gantry system is also presented. This work was supported in part by the U. S. Department of Energy under contract number DE-AC02-05CH11231.

The thorough realization of the advantages of the new generation x-ray light sources, such as the Upgraded Advanced Light Source (ALS˗U) under construction, requires near-perfect x-ray optics, capable of delivering light without significant degradation of brightness and coherence. The stringent requirements of beamline optics drive the state of the art in ex situ optical metrology. Here, we present the results of the ongoing efforts at the ALS X-Ray Optics Laboratory to develop a new generation long trace profiler, LTP-2020. We discuss the system design that incorporates different types of surface slope sensors. In addition to the classical pencil beam interferometry (PBI) sensor with an improved optical design, we develop a deflectometry sensor based on a customized electronic autocollimator (AC). By applying a new data processing algorithm to the AC raw image data available from the customized AC, we significantly reduce the quasi-periodic systematic error of the AC equipped with a small size aperture. We also treat the possibility to use the AC as a PBI sensor with external light beam sources based on super-luminescent emitting diode (SLED) and single-mode laser diode (SMLD). Operation modes with stationary and/or translated sensors are possible due to the two-carriage gantry system with adjustable vertical position. The variety of the available operation modes allows optimization of the LTP-2020 experimental arrangement for providing the best possible performance in measurements with state-of-the-art aspherical x-ray optics, variable-line-spacing diffraction gratings, and multi-element optical systems.

In Taiwan photon source facilities, soft x-ray beamlines are equipped with self-developed active high-precision mirrors or gratings. It is crucial to establish more advanced optical surface metrology instruments to satisfy the demands of optical production, installation, and testing in synchrotron optics. A long trace profiler (LTP) is an instrument used to measure the optical surface’s slope. This assists in monitoring the installation processes of optical instruments to ensure that the final optical components satisfy the required specifications in terms of quality. In this study, we propose a new air-bearing slide design to achieve nanometer-level precision for the LTP. This new design replaces ceramic and granite structures and addresses rail deformation and surface imperfections. This LTP features a specially designed bendable linear slide comprising four airbrushes, two shafts, and eight end mounts. The motion stage, supported and guided by four airbrushes against two parallel steel shafts, carries the optical head. End mounts are installed on the tilting stage at both ends, using flexure guides with manually adjusted screws and fine-tuning piezo. The rail system can be bent to a third-order polynomial rail profile to compensate for the effect of gravity when moving the optical head, enabling the achievement of the desired rail pitch variation within a distance of 400 mm with 2.5 μrad (RMS). To further enhance the precision, dynamic correction methods can be employed by utilizing PZT actuators and bender mechanisms. These mechanisms enabled rail pitch variation as low as 0.2 μrad (RMS).We introduce a new design for an air-bearing slide and its corresponding performance. This slide design is employed in LTP measurements. The outcomes of our study demonstrate a correlation between the observed results and the rail pitch profile.

The European XFEL generates extremely short and intense x-ray laser pulses, with high coherence and diffraction-limited divergence. It generates ultrashort x-ray ashes, 27000 times per second, with a brilliance that is a billion times higher than that of the best conventional x-ray radiation sources. Due to these extreme beam characteristics, the x-ray mirrors to transport and focus the beam need to be coated to protect them against beam damage. The surface quality of these mirrors before the coating is in the order of 2nm peak-to-valley and 200km radius on average. The ultra- at x-ray mirrors of ultimate precision are important in order to preserve the quality of the beam delivered to the experiments and the coating must not compromise the surface quality. This manuscript presents a preliminary study of the surface quality of 2 mirrors that will be part of the Optical Delay Line (ODL) before and after coating using Fizeau and White Light Interferometry.

In this paper we report on the modeling and characterization of transmission windows for in-situ interferometric measurements of cryogenically cooled mirrors. Specifically, we present a model of the temperature distribution and strain in the transmission window, and the corresponding spatial dependence of the window’s index of refraction. We also present experimental results which characterize the effect of the windows on interferometric measurement.

We present concept of the optical level deflection family of angle sensors capable of measuring deflection angle in range 0 – 0.15 rad with repeatability better than 10 nrad, and spot size of the order of 1 mm. The sensor family employs a set modern array detector. We derive an analytical formula describing shot noise level of the sensor and confirm it by numerical simulations. We find that for light beam spot size sufficiently larger than detector pixel size, and much smaller than array the shott noise does not depend on the spot size.

The Diamond-NOM slope profilometer has been in operation for more than 15 years in the Optics Metrology Lab at Diamond. It is an established instrument for accurate characterisation of x-ray optics for synchrotron and XFEL beamlines. However, continuous improvements in the fabrication quality of x-ray optics now means that polishing errors are comparable in magnitude to instrumental systematic errors. For x-ray optics with slope errors << 100 nrad rms and height errors < 1 nm, repeated measurements in multiple configurations are typically required to obtain accurate metrology data. To tackle such issues, we have developed a new instrument: the Diamond-VeNOM (velocity-NOM). VeNOM utilizes multiple autocollimators, synchronized with motion stages, to simultaneously measure the optical surface and monitor parasitic motion errors. A significant increase in measurement speed is achieved using 10x faster Elcomat5000 autocollimators. Motion trajectories are aligned with autocollimator data by temporarily blocking the beam paths using electronic shutters, based on triggering signals from positional encoders. Enhanced motion control capabilities allow user-defined velocity profiles of the scanning stage, coordinated with motorised pitch of the optic under test throughout the scan. This enables innovative dynamic scanning strategies, including on-the-fly, free-form, automated nulling of the optical surface throughout the scan to reduce systematic errors.

At Lawrence Berkeley National Laboratory’s Advanced Light Source, we are developing x-ray wavefront sensors to support the creation and operation of beamlines with diffraction-limited quality. Our new approach to rapid, intermittent wavefront sensing operates in reflection at glancing incidence angles and is compatible with the high-power densities of modern beamlines. For soft x-ray applications especially, the wavefront sensor can operate upstream of the exit slit in a vertically dispersed beam. This single-shot technique supports lateral shearing interferometry and Hartmann wavefront sensing; it can be adapted to speckle-based techniques as well. The reflected beam is directed to an off-axis YAG crystal that produces scintillated visible light. A small mirror reflects the light to a microscope and camera, and the measured wavefront shape information can be used as feedback to adaptive x-ray mirror elements. A compact array of gratings enables measurement across a broad range of photon energies or wavefront curvatures. We describe recent demonstrations at soft x-ray and hard x-ray wavelengths measuring an adaptive x-ray mirror, and a toroidal focusing mirror.

Here, we report the design, manufacturing, and characterization of x-ray optical components for the cavity-based x-ray free-electron laser (CBXFEL) cavity, in the framework of the CBXFEL R&D collaborative project of Argonne National Laboratory, SLAC National Accelerator Laboratory, and SPring-8. The optical components include high-reflectivity diamond crystal mirrors, reflecting and output coupling diamond drumhead crystal with thin membranes, focusing beryllium refractive lenses, and channel-cut Si crystal monochromators. All the designed optical components have been fully characterized at the Advanced Photon Source to demonstrate their desired performance for the CBXFEL cavity.

We have made significant progress in developing at-wavelength X-ray techniques and tools for optics characterization and beamline diagnostics at the Advanced Photon Source (APS). In the past few years, advanced techniques, such as the coded-mask-based method, are routinely used to characterize lenses, mirrors, crystals, and windows for APS and the APS upgrade projects at the 28-ID-B Instrumentation Development, Evaluation & Analysis (IDEA) Beamline and the 1-BM optics and detectors testing beamline. This paper reviews our recent achievements in developing at-wavelength metrology tools and activities in characterizing and developing advanced refractive optics for the APS upgrade beamlines. We summarize the quality evaluation results of hundreds of commercial lenses and highlight the measurement procedures and application of data in designing transfocators. We then discuss the characterization of APS-fabricated silicon compound refractive lenses (CRLs) for high-energy (>40 keV) focusing, and their potential application for the CHEX beamline (Coherent High- Energy X-ray Sector for In Situ Science). Silicon CRLs fabricated by Deep Reactive Ion Etching (DRIE) with different design parameters were evaluated at the IDEA beamline. At-wavelength metrology results show that silicon CRLs are promising options as high-energy focusing optics.

The soft x-ray regime is gaining adoption, specifically for the extreme ultraviolet (EUV) 13.5 nm wavelength used in today’s leading-edge semiconductor chip manufacturing. As miniaturization progresses and with the goal of continuing Moore’s Law, it becomes more difficult for chip makers to increase device densities in a 2D plane, even with leading-edge EUV photolithography. Chip makers are now turning to 3D-stacked architectures to increase area density. Since these stacked layers consist of micro-features and require precise interconnections, it is imperative that proper metrology be performed on each layer to identify possible defects and optimize the process on subsequent layers. There is a need for non-destructive imaging tools that can resolve nanometer-sized features. Soft x-ray imaging could be a solution using wavelengths from 2-20 nm. There are many methods of generating soft x-ray light, often with relatively high costs and varying outputs. This talk will highlight some cost-effective components that are commercially available. We will also present simulations of effective soft x-ray light output at the sample.