This PDF file contains the front matter associated with SPIE Proceedings Volume 11491, including the Title Page, Copyright information and Table of Contents.

The X-Ray Optics Working Group provides an informal setting for the interested engineers and scientists to meet and discuss issues related to the design, analysis, cooling, fabrication, and metrology of x-ray optics. Topics for discussion can be e-mailed to the organizer, Dr. Ali Khounsary (amk@iit.edu), prior to the meeting.

We report on a large-area, high-aspect-ratio, carbon nanotube (CNT) forest structure produced at BYU acting as a window/separator for a hollow cathode EUV lamp. The structure has large-surface-area, high light trans-mission, and differential pumping. CNT fabrication allows for variable dimensions, which allows various EUV distributions and pressure gradients to be possible. Theory is presented for predicting such distributions and gradients. Several structures have been fabricated; their dimensions, properties, and predicted distributions and gradients are given.

Sc/Si multilayer has excellent reflectivity at the wavelength of 35-50 nm and is expected to be fabricated for application in the solar EUV telescope, reflecting Ne VII line (46.5 nm) at normal incidence angle. For obtaining the stable narrow bandwidth, Sc/Si multilayers with different Sc thickness ratios were designed. And the structure and temporal stability of fabricated multilayers were studied. Sc/Si multilayers with a period thickness of about 24 nm were deposited by DC magnetron sputtering. The GIXR measurements indicated that interface diffusion was existed between Sc and Si layers. As the thickness ratio of the Sc increased, the width on Sc-on-Si interfaces increased. The surface roughness of these samples were no obviously different under AFM tests. After two months, the periodic structure and thickness were found to be stable. With a Sc thickness ratio value of 0.67, Sc/Si multilayer not only have the narrow bandwidth, but also have a good temporal stability.

Especially at grazing angles of incidence off-plane diffraction from blazed gratings is more efficient than in-plane diffraction. It will here be discussed, whether a soft X-ray monochromator employing such gratings can achieve competetive high spectral resolving power.

Planarization is important in many areas of nanostructure fabrication. Here we describe a new process for planarization saw-tooth surface of blazed gratings used for the monochromatization of light, but the applications should be much wider. Such gratings consist of relatively wide and very shallow triangular grooves with slanted facets which are machined with nanometer accuracy. The process of making such gratings includes planarization of a relatively coarse saw-tooth surface with micron deep grooves following by a plasma etch which provides reduction of the facet angle and hence groove depth by a factor of 10 - 100. To achieve high quality of the final grating the planarization step should provide a flat surface over the grating facets with sub-nanometer level planarity. We investigated planarization of coarse saw-tooth surfaces with a groove width of 10 μm and a facet angle of 4° by a polymer coating spun on the grating. The optimized planarization procedure provides 100% planarization even on these highly structured surfaces.

In addition to applications based on particle accelerator sources the XUV wavelength range is interesting for several further fields of research – for example in astronomy. On one hand, due to the short wavelengths a diffraction grating for these applications must provide a high-quality surface figure of its polished grating substrate or blank. On the other hand, the grating profile must be very smooth with no relevant phase errors to provide high diffraction efficiency as well as minimum stray light levels. Due to these challenging specifications it is advantageous if a manufacturer has access to lithographic technologies and sophisticated polishing processes at once. For instance, it is sometimes crucial to adapt the polishing to the employed technology chain in order to reach optimum grating performance. Furthermore, a capable grating manufacturing technology should enable flexible line distributions ranging from equally spaced lines on plane or curved substrates up to variable-line-spacing gratings (VLS) as well as even curved lines for imaging grating types in general. Grating surface figures ranging from plane, spherical and cylindrical up to freeform and – in case of beamline optics for grazing incidence operation mode – comparable massive grating blanks must be manageable as well. By employing holographic exposure in combination with new and state-of-the-art etching techniques it is feasible to address all the mentioned features. We will address the degrees of freedom in grating design arising due to holographic pattern definition and present latest improvements that go beyond the so far reported status of XUV grating manufacturing. Beside the flexibility of holography to achieve excellent roughness and best peak efficiency on silicon the option for local blaze adaption can be extremely beneficial. Thus, it will be in the focus of this text.

Focusing x-ray free-electron lasers (XFEL) allows us to study nonlinear optics within the xray region. Recently, we challenged the focusing XFELs to below 10 nm. However, the conventional multilayer Kirkpatrick-Baez(KB) mirrors require too strict alignment accuracy of the incident angle. To solve this problem, we propose advanced KB (AKB) mirrors, based on Wolter type III geometry. Because the configuration satisfies the Abbe sine condition, AKB mirrors enables a tolerance of incident angle error 1000 times greater than conventional KB mirrors. The remaining problem is how such mirrors are to be fabricated, because required shape accuracy is below 1 nm and the small radius of curvature on the mirrors makes high accuracy shape measurement difficult. In this work, we performed a mirror fabrication procedure based on a combination of a grating interferometer and a differential deposition. Experiment at BL29XUL of SPring-8 demonstrated AKB mirrors with an accuracy of λ/4 fabricated.

High-resolution imaging diagnosis of X-ray plasma distribution during implosion deceleration phase is urgently needed in inertial confinement fusion experiments. The current curved crystal imaging and the conventional Kirkpatrick-Baez microscope have a spatial resolution of 5 μm, so it is insufficient to obtain the evolution details of implosion target shell and hot spot. In this paper, an aspherical Kirkpatrick-Baez microscope is proposed, to achieve a higher spatial resolution. Simultaneously, an optical design method for aspherical structures is introduced. The imaging system has high reflectivity and good monochromatic performance using periodic multilayer technology. The characterization results show that this imaging system can reach a high spatial resolution of 2 μm in the central field of view.

Advances in x-ray techniques, including x-ray optics, have paved the way to obtain challenging results in several research fields thanks to the improvement in terms of spatial resolution. This is particularly true for x-ray fluorescence (XRF), where the combination of conventional x-ray sources with polycapillary optics has permitted to have high flux and high focused beams. However, XRF spectroscopy applied to archeological samples at a lab scale is mainly dedicated to qualitative studies. At the same time, quantitative analysis still remains a strong hurdle mainly due to important matrix effects that affect the signal related to the chemical components under evaluation. In this respect the adoption of x-ray optics on both the source and the detector represents a way to improve the signal to noise ratio, necessary for quantitative analysis. At LNF XLab Frascati the expertise, gained on x-ray techniques and on polycapillary lenses, has allowed researchers to carry out advanced μXRF studies. RXR (Rainbow X-ray), is the experimental station dedicated to 2D/3D XRF micro-imaging and TXRF analysis, being equipped with 2 detectors of different energy efficiency (covering a full spectrum from 800 eV to 25 keV) and working in confocal mode with the source coupled with a full-lens and both the detectors combined with dedicated half-lenses. This report aims in depicting the RXR potentialities through the results obtained in 2 case studies dedicated to carry out a semi-quantitative analysis of 2 different artifacts (an ancient book, a Buddhist scroll) by μXRF characterization.

X-ray absorption spectroscopy experiments are the primary scientific focus of the MRCAT bending magnet beamline, 10-BM of the Advanced Photon Source at Argonne National Laboratory. This technique is used for ex situ and in situ structural characterization of materials, many of which are non-crystalline. An intense X-ray beam is often required for these experiments. This beamline presently operates using a detuned double crystal monochromator system without any focusing. Typically, samples are illuminated by a 0.5 x 0.5 mm² monochromatic beam with a photon flux in the range of 2 - 9 x 10⁸ photons/s (in the 5 - 33 keV range). In this study, several alternate focusing schemes to capture a large portion of the bending magnet beam are compared. It is shown that, in principle, one can obtain an increase over two orders of magnitude in photon flux. These beamline schemes are outlined comparing them for photon flux, energy resolution, cost, and complexity in design and operation.

In this paper we provide an update on the development of a novel cantilevered-liquid-nitrogen-cooled-silicon mirror for a new insertion device beamline included in the Advanced Light Source Upgrade (ALS-U). The goals of this mirror development are to achieve diffraction limited performance, demonstrate reliability, minimize coolant flow induced vibration, and demonstrate carbon contamination prevention and cleaning techniques. In this paper we summarize the design requirements, the design of the mirror system, and prototype fabrication.

High-end precision optics are generally manufactured through traditional processes, which produce unique shapes and smooth surfaces, and the modern figure correction process. Particularly for soft x-ray regions, the demand for accurate free-form optics with complex and steep shapes has been increasing recently. Wolter mirrors and ring-focusing mirrors are representative of these types of optics, which are expected to be the next-generation devices for soft x-ray microscopy. To fabricate these mirrors with sufficient accuracy to achieve ideal optical performances, both traditional and modern processes must be optimized ad hoc. In this study, we apply the high-precision lens fabrication process to a monolithic Wolter mirror and a ring-focusing mirror. The surface measurement results of the mirrors suggest that it is possible to fabricate single-nanometer accurate soft x-ray mirrors with steep shapes in complex geometries.

The advanced light source including Free Electron Laser (FEL) and Synchrotron Radiation Facility, active X-ray optics is very important for X-ray transport with high efficiency in beamlines, which has been proved by the decade’s development and application of bimorph mirrors. In this report, we report a new type of X-ray active optics - the deformable mirror based on thermal-heat effect. Simulation results shows that the mirror provides high spatial resolution over traditional bimorph mirror. In addition, the features of simple process and low cost make it possible to reduce high quality requirement on other X-ray optics.

PZT-glued bimorph deformable mirrors are widely used in hard X-ray regimes; however, they haven’t been used in soft X-ray regimes because they are less compatible for usage under high vacuum. Therefore we have developed a glue-free bimorph deformable mirror, in which silver nano-particles were employed to bond PZT actuators to mirror substrates. However at long type, precise shape control had been hard since its mirror size was longer than PZT plate length whose gap between each PZT enevitablly existed. These gap area cannot be bended. In this study, we developed deformable mirror using triangle shaped PZT which aim is to reduce gap effect even at long mirror. At the simulation result, the gap effect would be reduced to be under 0.01 nm even at maximum bending. Also, vacuum tests of PZT glue-free bimolph mirror were also conducted. The final degree of vacuum obtained 9×10-8 Pa that was same as background level.

Electroforming replication is an essential technique for fabricating full-shell, grazing-incidence mirrors for use in space, laboratories, and synchrotron experiments. For X-ray astronomy, a nickel electroforming replication process was developed and is used to produce lightweight and high-resolution X-ray mirrors. In addition, the electroforming process for fabricating X-ray mirrors for use in synchrotron experiments has undergone remarkable development over the past decade. We expect that the use of the ground-based electroforming replication process for the production of optics for Xray astronomy will lead to further improvements in the performance of X-ray telescopes. This paper describes our ongoing development efforts in the nickel-electroforming replication process, including the results of a pilot study.

The focusing mirrors for the new LCLS soft x-ray (SXR) experimental hutches are tangential pre-shaped mirrors mounted in a Kirkpatrick Baez configuration. The mirrors are prefigured with an elliptical profile, coinciding with the longest working focal distance. The mirrors are equipped with benders to enable focusing of the beam at different experimental stations and to work out of focus with an uniform beam. To add complexity to the system, the mirrors are also water-cooled and need to fit in a very tight space, due to real estate limitation. For ensuring that the mirror profile is maintained at its sub-nm quality after the assembly of the mirror into its cooling and mechanical system, these mirrors need to undergo an extensive optics metrology study. The vertical and horizontal KB mirrors are first checked for twist error due to the mounting of the mirror substrate to its mechanics. This is measured with grazing incidence Fizeau interferometry. Then the mounted mirror needs to be shimmed to correct for any errors that may be caused by gluing of the mirror. This step requires a sequence of shimming and metrology measurement and must be repeated until the mirror shape is satisfactory. In addition, the mirror bender response function must be well-characterized and documented for the commissioning as well as operation of these mirrors in the experimental hutches. The response function can be attained by measuring the mirror profile using the instruments available in the LCLS Optics Metrology Laboratory and the stitching techniques developed at LCLS. The mirrors are scheduled to be installed in the new SXR beamline in spring 2020. Metrology data and initial commissioning results proving the performance of these wavefront preserving optics will be presented in this report.

A new X-ray Reflecto-Interferometry (XRI) technique is proposed and realized for thin-film characterization. The XRI employs refractive optics that produce a converging fan of radiation, incident onto a sample surface, and a high-resolution CCD detector, which simultaneously collects the reflecto-interferogram over a wide angular range. The functional capabilities of the new method were experimentally tested at the ESRF ID06, and ID10 beamlines in the X-ray energy range from 14 keV to 22 keV. The free-standing Si3N4 membranes with different thickness were studied. The main advantages and possible future applications of the proposed reflecto-interferometry are discussed.

Fabrication of optics components for x-ray applications is arguably one of the most challenging production tasks. They require incredible tolerance along with tight control on surface roughness. For example in case of refractive optics 1 micron r.m.s. shape error and <100 nm Sa surface roughness is needed on mm-scale geometries. Femtosecond laser ablation paired with inline metrology is a promising method to achieve the required parameters. Due to short pulse duration the workpiece experiences less thermal stress which is beneficial when it comes to the possibility of internal stress and crystal lattice damage. Various materials from tungsten to diamond can be processed with lasers. Combined with secondary operations like polishing laser microfabrication can be utilized in various state of the art components required for X-Ray community. In this presentation we will review several applications in refractive optics: diamond CRL, phase plates and others.

Various types of X-ray focusing optical systems are used at X-ray synchrotron radiation and free-electron laser facilities. However, these are designed for specific purposes and fixed optical parameters such as the numerical aperture (NA). Their lack of adaptability limits their application targets. In this research, we developed an X-ray adaptive focusing optical system which can control the beam size without moving the position of focus. The optical system consists of two deformable mirrors in one dimension. To vary the focused beam size, the NA is controlled by deforming the shape of the mirrors from concave to convex. The results will be presented along with the aberration properties estimated by ray trace and wave optical methods.

This article showcases the high-resolution control of an elliptically bent hard X-ray mirror optics at the Advanced Photon Source. The mirror uses a compact laminar flexure bending mechanism to achieve elliptical shapes covering a large range of focal distances. An array of capacitive sensors are used as a surface profiler for in-situ monitoring of the mirror shape. Machine learning and control techniques were used to change the mirror shape and focus the incident X-ray at predefined focal planes. The mirror surface shape error can be controlled to be within 40 nm rms with high repeatability. This technique gives the capability to focus incident X-ray beam within a range of focal distances corresponding to shape deformation range of a mirror optics. This work would be beneficial for controlling similar adaptive optics for multiple adaptive optics systems.

Polycarbonate based Laser Eye Protection (LEP) were aged and solarized under UV radiation using Atlas Ci4000 Xenon Weather-Ometer , measured their optical and ballistic performance, also carried out the environmental assessment for theses LEP. The samples were characterised after solarisation using Carry 6000i spectrophotometer in order to measure their optical density and find the changes in their optical performance and properties before and after solarisation. In this study, we carried out the following environmental assessment, High and low Temperature, Temperature Shock and Aggravated Humidity.All these environmental assessment have no effect on the optical performance of these LEP. High humidity alone does not affect the optical density (OD) The combination of humidity and solarisation has a significant impact on optical density.

Mirror-based zoom optics systems can offer variable focal spot sizes over a wide range, which is essential for coherent nanoprobe beamlines, such as the proposed Atomic beamline in the Advanced Photon Source (APS) upgrade project. The success of the zoom mirror system in the nano-focusing regime requires the development of high-precision deformable mirrors, in-situ surface profilers and wavefront sensors, and advanced feedback control system. A prototype 1-D zoom mirror system consists of two vertical focusing mirrors was designed, assembled, and tested at the APS 1-BM beamline. The system consists of a bender-based mirror with a capacitive-sensor- array-based real-time mirror profiler, a bimorph adaptive mirror, and a grating interferometer for the wavefront monitoring. In this work, we present the design and test results of the prototype system demonstrating its zoom focusing capability.

We demonstrate the capabilities of ion-beam lithography (IBL) for the manufacturing of the X-ray refractive micro-optics. For the first time with the help of IBL, the hardest of current materials – diamond – was milled, and microscale diamond half-lenses were produced. Lenses have a rotationally parabolic profile with radii of parabola apexes in the range from 3 to 10 μm. As has been confirmed with SEM, the surface of produced lenses was free of low- and high-frequency modulations: figure errors of fabricated lenses were < 200 nm, while the surface roughness was estimated to be 30 nm. The optical performance of the lens was successfully tested at a third-generation synchrotron, where the lenses provided diffraction-limited focusing of X-ray radiation and demonstrated intensity profiles with Gaussian distributions at every measured longitudinal position (along the optical axis) downstream of the optics.

Using femtosecond laser technique, ‘long type’ kinoform lenses designed with single foci are made for both soft X-ray range(around 800ev) and hard x-ray range(12kev). The soft x-ray lenses are made of SU8 photoresist by two-photon polymerization(TPP) technique while the hard x-ray lens is made of sapphire using femtosecond laser ablation. Physical aperture of the soft X-ray SU8 lenses reaches 90 microns with one centimeter focal length. The hard X-ray sapphire lens has aperture size at around 210 microns but much larger focal length of 5 meters. These lenses show promising usage of ultrafast femtosecond laser in making complicated x-ray lenses though much works are still needed to improve the fabrication process.