This PDF file contains the front matter associated with SPIE Proceedings Volume 11492, including the Title Page, Copyright information and Table of Contents.

The National Metrology Institute of Technology provides a flatness calibration service for large flat substrates using a Fizeau interferometer with 10 nm (k = 2) uncertainty over a measurement range of 300 mm. In the Fizeau interferometer, the surface profile of the reference flat is a measurement error factor because the measurand is the gap distance between the reference flat and the specimen. We have reduced uncertainty by constructing a surface profile map of the reference flat based on the three-flat test; however, it is difficult to manufacture a highly accurate reference flat and create a correction surface profile map in order to measure even larger flat substrates. Thus, we developed a three-dimensional scanning deflectometric profiler (3-D SDP) that does not require a reference flat and can directly measure a surface profile. Measuring devices based on deflectometry have been developed by many laboratories for highly accurate straightness profile measurement, but measurement by such systems is limited to a line (two-dimensional) profile. To solve this problem, we developed a novel method of measuring the surface topography by calculating the topography from radial lines obtained by rotating the specimen. In this study, we compared measurements between the Fizeau interferometer and 3-D SDP. We also report the results of measuring an optical flat with a diameter of 300 mm.

The optical design of the Long Trace Profiler optical system is explored with a commercial raytrace program, Zemax OpticStudio™ (ZOS)1, with the intent of finding and correcting sources of systematic error. ZOS provides both geometric raytracing tools and physical optics Gaussian beam propagation and diffraction image calculation tools, and two design modes, sequential component (SC) and non-sequential component (NSC) that are optimized for different aspects of the design process. The original LTP-II system employs a singlet lens with a 1250 mm focal length. It is optimized to provide minimum distortion over a surface slope angle range of ±5 mrad. Using the ZOS tools, we are able to simulate ghost rays that produce distortion in the beam spot image and can minimize the distortion by deliberate misalignment of the beamsplitter (BS) components. Unfortunately, the reference beam is compromised because of the component tilts. The most recent LTP500 system design simplifies the optical system and makes the reference beam usable again, even with misalignment of the polarizing beamsplitter (PBS). Two lenses are designed for the LTP500 – a cemented doublet that has been fabricated, and a singlet with one aspheric surface. Both have focal distances of 500 mm with an expanded angular measurement range of ±10 mrad. The aspheric singlet provides superior performance. ZOS allows the import of wavefront measurement data produced by commercial interferometer software. We apply the wavefront error measurement from the cemented doublet to the model to show that the 19nm RMS wavefront error needs to be improved by at least a factor of ten in order to reduce the systematic error to a level that will allow the LTP to approach its design limit of a few tens of nanoradians.

To fully exploit the advantages of fourth-generation synchrotron light sources, diffraction-limited-storage-rings (DLSR) and fully coherent free electron lasers (FELs), beamline mirrors and diffraction grating must be of exceptional quality. To achieve the required mirror and grating quality, the metrology instrumentation and methods used to characterize these challenging optics and, even more so, optical assemblies must also offer exceptional functionality and performance. One of the most widely used slope measuring instruments for characterizing x-ray optics is the long trace profiler (LTP). The easily reconfigurable mechanical design of the LTP allows optimization of the profiler arrangement to the specifics of a particular metrology task. Here, we discuss the optical schematic, design, and performance of an original multifunctional light beam source that provides functional flexibility of the LTP optical sensor. With this source, the LTP can be easily reconfigured for measurements of x-ray mirrors or diffraction gratings that have widely different source coherence requirements. Usage of a source with a low degree of coherence for mirror metrology helps to suppress the LTP systematic errors due to spurious interference effects in the LTP optical elements. A high-coherence narrow-band source is used for groove-density-distribution characterization of x-ray diffraction gratings. The systematic error and spatial resolution of the LTP with the different sources is also measured and analyzed.

In recent years, optical elements with freeform or aspherical surface have been required in various fields. Nano-accuracy three-dimensional measurements are needed to make them. As general methods for measuring the surface shape of optical elements, there are CMM and interferometer. However, the uncertainty of CMM is about 100 nm. Further, the interferometer cannot perform absolute measurement, and it is difficult to evaluate uncertainty. Therefore, there is no method which can measure the shape of optical elements with nano-scale uncertainty. Then, we develop a non-contact three-dimensional figure error measurement method using normal vector tracing method. The principle of our method is that normal vectors at each measured point are decided by making the incident light beam on the mirror surface and the reflected beam at same point coincide. Our method has already achieved sub-nanometer repeatability. In this paper, we report the result of evaluating uncertainty of our measurement.

Side-deflecting cylindrical mirrors with sagittal curvature horizontally deflect and focus the beam in the vertical direction. This optical scheme applied to fourth-generation synchrotron light source beamlines has potential advantages leading to nearly aberration-free focus and variable beam size or focus position. We characterize the surface quality of sagittal cylinders in the low spatial frequency range with the long trace profiler (LTP) and the Fizeau interferometer (FZI). In the standard LTP, the sagittal curvature of the cylindrical mirror causes the reflected laser beam to diverge, which consequently shifts the focus out of the detector plane, turning a reliable measurement impossible. Therefore, a positive cylinder lens is placed at Cat's eye position to recollimate the beam. In this paper, we describe the alignment procedure and dene the required accuracy of each degree of freedom for both the cylinder lens and the cylindrical mirror to be characterized. Measurements with the FZI are limited to optics with small curvatures when measuring with a flat reference. We show that measuring a sagittal cylinder slightly out-of-focus overcomes this limitation. Measurements with the FZI also allow to characterize the deformations caused by clamping forces due to fixation. We compare the measured deformation with Finite Element Analysis (FEA) simulation results. We present measured surface height and slope profiles (LTP and FZI) of cylindrical mirrors for SIRIUS beamlines.

Production of over 600 ultra-smooth mirrors has been achieved by JTEC Corporation since 2006, which can be recognized as the evidence of large contribution to development of x-ray optics. To fabricate these mirrors, extremely high-accuracy surface shape measurement technology is necessary, therefore, RADSI, which is developed by Osaka University, has been applied to the manufacturing over the ages [1, 2]. In recent years, however, according to the growth of demand for a higher demagnification and a larger area light reception, surface curvature becomes steeper, thus, RADSI alone does not cover all mirrors. In order to resolve this matter, coordinate measuring machine (CMM) have been developed. In this study, the measurement performance of this CMM is discussed on the basis of the comparison with RADSI.

The small radius x-ray mirror in the interferometer stitching measurement is needed high angle resolution rotation stage to get reliable angle information. The rotation stage rotary range requirement is not wide, because of the X-ray mirror radius generally large than 200M, and the mirror length small than 1.2M. The angle resolution is needed high resolution, therefore, in interferometer stitching measurement, the interferogram is easily affected by the rotation angle difference. Thus, this study is to design a small angle traveling range (rotation angle maximum ± 1.5 degrees), high angle resolution (10 nrad.), and high loading capacity (loading maximum 75 Kg) rotation stage, the rotation mechanism is applied pivot bearing to get high-resolution rotation angle. The rotation stage design is finished, this article discusses system assembly and test.

High precision metrology and deterministic fabrication are two indispensable techniques for making advanced X-ray mirrors. Among the various metrology and fabrication methods, we are currently developing stitching interferometry and profile coating/differential deposition techniques as a first step for this. For the development of curved focusing mirror, stitching interferometry method was studied. It is based on a global stitching algorithm taking into account the information in the overlapped area of several neighboring subapertures to finish the measurement. The method was tested on a spherical mirror with a radius of 100 m. A smallest repeatability error of 0.24 nm RMS over the two-dimensional surface is demonstrated. The stitched result was compared with NOM in Shanghai Synchrotron Radiation Facility to examine the absolute accuracy. Based on the stitching interferometry, a vertical focusing mirror of KB system was fabricated by using the profile coating technique. Through several iterations, an initial sphere mirror was modified into the desire elliptical mirror with a one-dimensional figure error (along the center line) of around 1.49 μrad RMS over 50 mm length compared with the designed ellipse.

The long trace profiler, LTP-II, available at the Advanced Light Source (ALS) X-ray Optics Laboratory (XROL), was recently upgraded by replacing a multimode diode laser light source with a single-mode, wavelength-stabilized, fibercoupled diode laser system. The upgrade enables us to reliably characterize the lateral variation of groove density of variable-line-spacing (VLS) x-ray diffraction gratings. Here, we discuss the LTP-II performance with an example of measurements with a VLS grating with the groove density at the grating center of 300 lines/mm. For the measurements, we use the LTP-II in two different operation arrangements, the single Gaussian beam and the pencil beam interferometer arrangements. For each operation arrangement, we apply two data processing algorithms: with calculating the centroid position and with determining the position of a characteristic features of the detected beam intensity distributions. We discuss the observed strong correlation between the LTP-II modes of operation and the resulted (extracted) groove density variations. We also speculate on possible origin of the correlation.

To achieve an ultrahigh-resolution for soft X-ray beamlines, the slope error of a highly precise grating is required on the level of 0.1 μrad root-mean-square (RMS) under thermal loading. To realize the goal, a specially designed 25-actuator optical surface bender for the gratings and mirrors is developed and operated at Taiwan Photon Source (TPS) [1]. In this paper, the construction and operation of the in situ LTP measuring system is described[2]. This LTP consists of a switchable optical reflection system that let the LTP can switch to measure horizontal or vertical mounting mirrors/gratings in the beamline. The other is a low optical distortion and bakeable to 120 ˚C glass viewport which is used for the ultra-high vacuum[3,4] interface for the beamlines optics and LTP. The surface slope error being reduced down to 0.1 and 0.15 μrad (RMS) by the 25-actuator bender without/with the glass viewport as verified by the in situ LTP measurements in the beamline.

Over more than 50th years Thales SESO represent a world leading designer and manufacturer of high-end, optical components such as telescopes and satellite-based space observation optics operating over the entire spectral range from infrared to x-ray wavelengths. Since early 90th we are actively working in the EUV, Soft-X-ray and hard X-ray spectral range, by developing new equipment and introducing metrology innovations and brand new patented products such as bender and bimorphs mirrors (1st and 2nd generation). In particular a set of customized solution and integrated system for imaging and spectroscopy have been developed basing on the original Wolter and Kirckpatrick-Baez design. Few example of reflective optics behaving both, as collimator, focusing and imaging device are discussed in this paper. A set of solutions to realize fixed curvature optics and dynamically bended device will be detailed to illustrate the flexibility and performances of these products..

Optical components in optics hutches of a hard x-ray undulator beamline of BL05XU at SPring-8 was restructured for providing a high flux beam at 1% bandwidth in the x-ray energy range from 5 to 100 keV. The so-called pink beam by a double-multilayer monochromator or total reflection mirrors pair with a prism made of glassy carbon as a harmonic separator are prepared in this beamline. The total reflection mirrors have three stripes; rhodium and platinum coated surface and silicon uncoated surface. Additionally, a silicon single crystal monochromator and a silicon channel cut crystal monochromator with liquid nitrogen cooling system are planned to be installed. The installation of these optical components started at January 2020. The commissioning of some components using undulator radiation will be started at April 2020.

We evaluated the effect on the beam image from an x-ray plane mirror and some kinds of an x-ray window by grating interferometer at wavelength and off-line metrology in order to improve the uniformity of the x-ray. Based on wave optical simulation the figure error of the plane mirror was improved in specific spatial wavelength and the additional polished mirror has been succeeded in reduction of the fluctuation as estimated. In this paper we report the current status and discuss specification of total reflection mirror and x-ray window aiming at x-ray beamline optics in the next generation light source.

X-ray reflecto-interferometry technique based on compound refractive lenses using an x-ray laboratory source was proposed to study thin-film structures. The setup for this experiment is very simple: a focused x-ray beam is reflected from parallel flat surfaces, which creates an interference pattern in a wide angular range, therefore the interference pattern can be obtained in a single shot without the need to rotate the sample or the detector. The reflecto-interferograms for Si₃N₄ membranes were obtained using the MetalJet Excillium micro-focus laboratory source with GaKα emission line at 9.25 keV. The experimentally obtained film thickness is in good agreement with the declared characteristics.

Since a replication-type of the Wolter mirror is obtained as the negative shape of its mandrel via shape replication represented by electroforming, a high precision mandrel fabrication process is essential for nano-focusing with the mirror at synchrotron radiation facilities. In particular, three-dimensional shape measurement technique for the mandrel is required. In this study, we developed the high precision three-dimensional shape measurement system dedicated for the Wolter mandrels. First, the shape error distributions of the ellipsoidal surface and the hyperboloid surface were measured independently. The geometrical relation between the surfaces was constrained by the longitudinal profiles which include the intersection measured by a profilometer. The diameter was also measured and finally the three-dimensional shape distribution was obtained. Applying this system, we fabricated a high precision Wolter mandrel.

Focusing x-rays is a key technology for x-ray microscopic techniques. In a soft-x-ray region, focusing systems with achromaticity and a high numerical aperture have long been desired as a substitute for Fresnel zone plates. Ellipsoidal mirrors are promising focusing optics for such systems. However, two technical problems have to be overcome to allow practical application of these mirrors: their low efficiency due to their hollow shapes and strict requirements for their alignment. A novel focusing system using two reflective mirrors was proposed for this purpose. The downstream mirror is a quasi-Wolter mirror with a hollow shape similar to an ellipsoidal mirror and has a high numerical aperture of more than 0.1. The tolerance of the setting angle error of the quasi-Wolter mirror is significantly large compared to that of the ellipsoidal mirror because a quasi-Wolter mirror reflects the incident rays twice. The upstream mirror is a ring-focusing mirror, which produces an x-ray beam with a ring-shaped intensity profile, ensuring the entire beam reflects onto the quasi-Wolter mirror and reaches the focus of the system. The proposed system is ideal for soft-x-ray focusing. The design procedure and formulas are described in the present study. A prototype of the system is designed for BL25SU-A of SPring- 8. The ideal focusing spot size is estimated by numerical simulation to be 10 nm at 300 eV. The influence of alignment errors of the two mirrors is also simulated and summarized.

The wavelet-transform-based single-shot X-ray speckle tracking (WXST) method combined with a multi-resolution analysis process was proposed to provide higher noise robustness and faster data processing compared with the correlation-based single-shot X-ray speckle tracking (CXST) technique. The new method was experimentally validated by measuring phase errors of beryllium compound refractive lenses in the transmission geometry. Taking advantages of the wavelet transform and the multi-resolution analysis, the data-analysis efficiency can be improved by two orders of magnitude for samples with phase variation over a large dynamical range. The multiresolution WXST method also shows high reconstruction accuracy and noise robustness. This novel method can broaden the potential applications of speckle-tracking techniques in wavefront sensing, at-wavelength metrology and phase imaging by breaking the bottleneck of the data processing.

X-ray focusing optics are essential for acquiring high-quality X-ray microscopy images. Fresnel zone plates (FZPs) are conventionally used to focus soft X-rays via diffraction. The use of Kirkpatrick-Baez (KB) mirrors for nanofocusing in the soft X-ray region is limited because a KB mirror is a reflective X-ray focusing optic that has a pair of perpendicular mirrors in a grazing-incidence configuration, which lowers the numerical aperture due to the long focal length. KB mirrors with a short focal length have been proposed for hard X-ray focusing. This paper presents the design of an ultrashort KB mirror for soft X-ray focusing that has an extremely short focal length, which is achieved by reducing its mirror length. Moreover, a large grazing angle is employed to utilize total-reflection-based focusing. An ultrashort KB mirror is proposed for pilot studies at beamline BL25SU-A, SPring-8, Japan. A ray-tracing simulator is used to determine the misalignment tolerance in terms of roll and yaw for each mirror in the KB geometry. Based on the results, a mirror manipulator and other equipment are designed to precisely position the mirrors. Although this strategy, commonly used for FZPs, leads to a short working distance and a small beam acceptance, we believe that it can be applied to ultrashort KB mirrors for X-ray microscopy applications with achromaticity and strong demagnification.

In this paper, we present an interferometric method to measure the shape of X-ray wavefront and the slope error of optical elements using microfocus x-ray source. According to the fractional Talbot effect, we built an x-ray grating interferometer for x-ray wavefront characterization at the working wavelength. The interferometer consists of a phase grating as a beam splitter and an absorption grating as a transmission mask for the detector. however, the determination of the relation between x-ray grating interferometer system parameters and the sensitivity, which is influenced by many optical elements in the system, is crucial for the optimization of the setup. It is very complicated to determine the best optical parameters in the course of experiment. The interferometry system is abstracted into a linear system, and then a mathematical model is constructed. The influence of different physical parameters, such as the source size and the energy spectrum, on the functional capability of an x-ray grating interferometer applied for X-ray wavefront characterization is discussed using numerical simulations based on Fresnel diffraction theory. The slope variations can be detected with an accuracy better than 100nrad.