A new design for a double-sided high-pressure diamond anvil cell laser heating set-up is described. The prototype is deployed at beamline 12.2.2 of the Advanced Light Source at Lawrence Berkeley National Lab. Our compact design features shortened mechanical lever arms, which results in more stable imaging optics, and thus more user friendly and more reliable temperature measurements based on pyrometry. A modification of the peak scaling method was implemented for pyrometry, including an iterative method to determine the absolute peak temperature, thus allowing for quasi-real time temperature mapping of the actual hotspot within a laser-heated diamond anvil cell without any assumptions on shape, size, and symmetry of the hotspot and without any assumptions to the relationship between fitted temperature and peak temperature. This is important since we show that the relationship between peak temperature and temperature obtained by fitting the Planck function against the thermal emission spectrum averaged over the entire hotspot is not constant but depends on variable fitting parameters (in particular, the size and position of the fitting window). The accuracy of the method is confirmed through measuring melting points of metal wires at ambient pressure. Having absolute temperature maps in real time allows for more differentiated analyses of laser heating experiments. We present such an example of the pressure variations within a heated hotspot of AgI at a loaded base pressure of 3.8 GPa.

Over the past decade, the advances in grating-based soft X-ray spectrometers have revolutionized the soft X-ray spectroscopies in materials research. However, these novel spectrometers are mostly dedicated designs, which cannot be easily adopted for applications with diverging demands. Here we present a versatile spectrometer design concept based on the Hettrick-Underwood optical scheme that uses modular mechanical components. The spectrometer’s optics chamber can be used with gratings operated in either inside or outside orders, and the detector assembly can be reconfigured accordingly. The spectrometer can be designed to have high spectral resolution, exceeding 10 000 resolving power when using small source (∼1μm) and detector pixels (∼5μm) with high line density gratings (∼3000 lines/mm), or high throughput at moderate resolution. We report two such spectrometers with slightly different design goals and optical parameters in this paper. We show that the spectrometer with high throughput and large energy window is particularly useful for studying the sustainable energy materials. We demonstrate that the extensive resonant inelastic X-ray scattering (RIXS) map of battery cathode material LiNi1/3Co1/3Mn1/3O2 can be produced in few hours using such a spectrometer. Unlike analyzing only a handful of RIXS spectra taken at selected excitation photon energies across the elemental absorption edges to determine various spectral features like the localized dd excitations and non-resonant fluorescence emissions, these features can be easily identified in the RIXS maps. Studying such RIXS maps could reveal novel transition metal redox in battery compounds that are sometimes hard to be unambiguously identified in X-ray absorption and emission spectra. We propose that this modular spectrometer design can serve as the platform for further customization to meet specific scientific demands.

The Advanced Light Source (ALS) beamline (BL) 10.3.2 is an apparatus for X-ray microprobe spectroscopy and diffraction experiments, operating in the energy range 2.4–17 keV. The performance of the beamline, namely the spatial and energy resolutions of the measurements, depends significantly on the collimation quality of light incident on the monochromator. In the BL 10.3.2 end-station, the synchrotron source is imaged 1:1 onto a set of roll slits which form a virtual source. The light from this source is collimated in the vertical direction by a bendable parabolic cylinder mirror. Details are presented of the mirror design, which allows for precision assembly, alignment and shaping of the mirror, as well as for extending of the mirror operating lifetime by a factor of ∼10. Assembly, mirror optimal shaping and preliminary alignment were performed ex situ in the ALS X-ray Optics Laboratory (XROL). Using an original method for optimal ex situ characterization and setting of bendable X-ray optics developed at the XROL, a root-mean-square (RMS) residual surface slope error of 0.31 µrad with respect to the desired parabola, and an RMS residual height error of less than 3 nm were achieved. Once in place at the beamline, deviations from the designed optical geometry ( e.g. due to the tolerances for setting the distance to the virtual source, the grazing incidence angle, the transverse position) and/or mirror shape ( e.g. due to a heat load deformation) may appear. Due to the errors, on installation the energy spread from the monochromator is typically a few electron-volts. Here, a new technique developed and successfully implemented for at-wavelength ( in situ ) fine optimal tuning of the mirror, enabling us to reduce the collimation-induced energy spread to ∼0.05 eV, is described.

The autocollimator and moveable pentaprism based DLTP [NIM A 616 (2010) 212-223], a low-budget, NOM-like profiler at the Advanced Light Source (ALS), has been upgraded to provide fast, highly accurate surface slope metrology for long, side-facing, x-ray optics. This instrument arrangement decreases sensitivity to environmental conditions and removes the gravity effect on mirror shape. We provide design details of an affordable base tool, including clean-room environmental arrangements in the new ALS X-ray Optics Laboratory with advanced temperature stabilization and turbulence reduction, that yield measurements in under 8 hours with accuracy better than 30 nanoradians (rms) for super polished,190 mm flat optics, limited mainly by residual temporal instability of the experimental set-up. The upgraded DLTP has been calibrated for highly curved x-ray optics, allowing same day measurements of a 15 m ROC sphere with accuracy of better than 100 nanoradians (rms). The developed calibration procedure is discussed in detail. We propose this specific 15 m ROC sphere for use as a round-robin calibration test optic.

Performance of state-of-the-art surface slope measuring profilers, such as the Advanced Light Source's (ALS) long trace profiler (LTP-II) and developmental LTP (DLTP) is limited by the instrument's systematic error. The systematic error is specific for a particular measurement arrangement and, in general, depends on both the measured surface slope value and the position along a surface under test. Here we present an original method to characterize or measure the instrument's systematic error using a bendable X-ray mirror as a test surface. The idea of the method consists of extracting the systematic error from multiple measurements performed at different mirror bendings. An optimal measurement strategy for the optic, under different settings of the benders, and the method of accurate fitting of the measured slope variations with characteristic functions are discussed. We describe the procedure of separation of the systematic error of an actual profiler from surface slope variation inherent to the optic. The obtained systematic error, expressed as a function of the angle of measurement, is useful as a calibration of the instrument arranged to measure an optic with a close curvature and length. We show that accounting for the systematic error enables the optimal setting of bendable optics to the desired ideal shape with accuracy limited only by the experimental noise. Application of the method in the everyday metrology practice increases the accuracy of the measurements and allows measurements of highly curved optics with accuracy similar to those achieved with flat optics. This work was supported by the U. S. Department of Energy under Contract No. DE-AC02-05CH11231.

Broadly applicable, in situ at-wavelength metrology methods for x-ray optics are currently under development at the Advanced Light Source. We demonstrate the use of quantitative wavefront feedback from a lateral shearing interferometer for the suppression of aberrations. With the high sensitivity provided by the interferometer we were able to optimally tune the bending couples of a single elliptical mirror (NA=2.7mrad) in order to focus a beam of soft x-rays (1.24keV) to a nearly diffraction-limited beam waist size of 156(±10)nm.

We demonstrate a comprehensive and broadly applicable methodology for the optimal in situ configuration of bendable soft x-ray Kirkpatrick-Baez mirrors. The mirrors used for this application are preset at the ALS Optical Metrology Laboratory prior to beamline installation. The in situ methodology consists of a new technique for simultaneously setting the height and pitch angle of each mirror. The benders of both mirrors were then optimally tuned in order to minimize ray aberrations to a level below the diffraction-limited beam waist size of 200 nm (horizontal) × 100 nm (vertical). After applying this methodology, we measured a beam waist size of 290 nm (horizontal) × 130 nm (vertical) with 1 nm light using the Foucault knife-edge test. We also discuss the utility of using a grating-based lateral shearing interferometer with quantitative wavefront feedback for further improvement of bendable optics.

Localized charge, spin and orbital degrees of freedom can compete with electronic itinerancy and such competition lies at the heart of emergent material properties. To study these electronic orderings, resonant soft X-ray scattering (RSXS) spectroscopy has been demonstrated as one of the most powerful direct probes, and its time-resolved capability can be implemented through pump-probe technique. The ultrafast/ultra-intense X-ray pulses from LCLS can be used as the probe in the time-resolved RSXS experiments, but the inherent fluctuations in intensity and timing between pulses can degrade the superior temporal resolution. To overcome such fluctuations, a compact fast CCD (cFCCD) was developed to enable shot-by-shot data acquisitions and a dedicated RSXS endstation, constructed to house this cFCCD and other single-channel photon detectors, has been extensively used at both ALS and LCLS. Time-resolved RSXS experiments on La1.75Sr0.25NiO4 nickelate have revealed an unexpected transient behavior of charge and spin ordering (CO/SO) states. After 800nm laser excitation, the CO can be fully suppressed at higher pump fluence while SO remains detectable, creating a transient state that is not accessible by tuning thermodynamic variables. Furthermore, two distinct time scales are identified in the recovery of CO and can be attributed to the amplitude (fast) and phase (slow) dynamics of order parameter. A new version of cFCCD, with eight times the detection area and the readout electronics moved into vacuum side to minimize the pickup noise, has been developed and will be incorporated into the RSXS endstation.

Systematic error and instrumental drift are the major limiting factors of sub-microradian slope metrology with state-of-the-art x-ray optics. Significant suppression of the errors can be achieved by using an optimal measurement strategy suggested in [Rev. Sci. Instrum. 80, 115101 (2009)]. Here, we report on development of an automated, kinematic, rotational system that provides fully controlled flipping, tilting, and shifting of a surface under test. The system is to be integrated into the Advanced Light Source long trace profiler, LTP-II, allowing for complete realization of the advantages of the optimal measurement strategy method. We describe in detail the system's specification, design operational control and data acquisition. The performance of the system is demonstrated via the results of high precision measurements with a number of super-polished mirrors.

Realizing the experimental potential of high-brightness, next generation synchrotron and free-electron laser light sources requires the development of reflecting x-ray optics capable of wavefront preservation and high-resolution nano-focusing. At the Advanced Light Source (ALS) beamline 5.3.1, we are developing broadly applicable, high-accuracy, in situ, at-wavelength wavefront measurement techniques to surpass 100-nrad slope measurement accuracy for diffraction-limited Kirkpatrick-Baez (KB) mirrors.The at-wavelength methodology we are developing relies on a series of wavefront-sensing tests with increasing accuracy and sensitivity, including scanning-slit Hartmann tests, grating-based lateral shearing interferometry, and quantitative knife-edge testing. We describe the original experimental techniques and alignment methodology that have enabled us to optimally set a bendable KB mirror to achieve a focused, FWHM spot size of 150 nm, with 1 nm (1.24 keV) photons at 3.7 mrad numerical aperture. The predictions of wavefront measurement are confirmed by the knife-edge testing.The side-profiled elliptically bent mirror used in these one-dimensional focusing experiments was originally designed for a much different glancing angle and conjugate distances. Visible-light long-trace profilometry was used to pre-align the mirror before installation at the beamline. This work demonstrates that high-accuracy, at-wavelength wavefront-slope feedback can be used to optimize the pitch, roll, and mirror-bending forces in situ, using procedures that are deterministic and repeatable.

Brightness preservation requirements for ever brighter synchrotron radiation and free electron laser beamlines require surface slope tolerances of x-ray optics on the order of 0.2 μrad, or better. Hence, the accuracy of dedicated surface slope metrology must be 0.1 μrad, or even less. Achieving this level of measurement accuracy with the flagship instrument at synchrotron radiation metrology laboratories, the Long Trace Profiler (LTP), requires all significant sources of systematic, random, and instrumental drift errors to be identified, and reduced or eliminated. In this respect, the performance of certain components of the Advanced Light Source LTP-II design [Kirschman, et al., Proc. SPIE, 7077, 70770A-12 (2008)] is analyzed, considering the principal justification for inclusion of each component, possible systematic error due to the quality of its optical material, and drift effects due to generated heat, etc. We investigate the effects of replacement of the existing diode laser with a fiber-coupled laser light source, and demonstrate that reducing the number of components by using a single beam on the surface under test (SUT), rather than an original double beam maintains, or even improves the accuracy of measurement with our LTP. Based on the performance of the upgraded LTP, we trace the further steps for improving of the LTP optical system.

A new low-budget slope measuring instrument, the Developmental Long Trace Profiler (DLTP), was recently brought to operation at the ALS Optical Metrology Laboratory. The design, instrumental control and data acquisition system, initial alignment and calibration procedures, as well as the developed experimental precautions and procedures are also described in detail. The capability of the DLTP to achieve sub-microradian surface slope metrology is verified via cross-comparison measurements with other high-performance slope measuring instruments when measuring the same high-quality test optics. The directions of future work to develop a surface slope measuring profiler with nano-radian performance are also discussed.

Nano-focusing and brightness preservation for ever brighter synchrotron radiation and free electron laser beamlines require surface slope tolerances of x-ray optics on the order of 100 nrad. While the accuracy of fabrication and ex situ metrology of x-ray mirrors has improved over time, beamline in situ performance of the optics is often limited by application specific factors such as x-ray beam heat loading, temperature drift, alignment, vibration, etc. In the present work, we discuss the recent results from the Advanced Light Source developing high accuracy, in situ, at-wavelength wavefront measurement techniques to surpass 100-nrad accuracy surface slope measurements with reflecting x-ray optics. The techniques will ultimately allow closed-loop feedback systems to be implemented for x-ray nano-focusing. In addition, we present a dedicated metrology beamline endstation, applicable to a wide range of in situ metrology and test experiments. The design and performance of a bendable Kirkpatrick-Baez (KB) mirror with active temperature stabilization will also be presented. The mirror is currently used to study, refine, and optimize in situ mirror alignment, bending and metrology methods essential for nano-focusing application.

A new facility for microdiffraction strain measurements and microfluorescence mapping has been built on beamline 12.3.2 at the advanced light source of the Lawrence Berkeley National Laboratory. This beamline benefits from the hard x-radiation generated by a 6 T superconducting bending magnet (superbend). This provides a hard x-ray spectrum from 5 to 22 keV and a flux within a 1 microm spot of approximately 5x10(9) photons/s (0.1% bandwidth at 8 keV). The radiation is relayed from the superbend source to a focus in the experimental hutch by a toroidal mirror. The focus spot is tailored by two pairs of adjustable slits, which serve as secondary source point. Inside the lead hutch, a pair of Kirkpatrick-Baez (KB) mirrors placed in a vacuum tank refocuses the secondary slit source onto the sample position. A new KB-bending mechanism with active temperature stabilization allows for more reproducible and stable mirror bending and thus mirror focusing. Focus spots around 1 microm are routinely achieved and allow a variety of experiments, which have in common the need of spatial resolution. The effective spatial resolution (approximately 0.2 microm) is limited by a convolution of beam size, scan-stage resolution, and stage stability. A four-bounce monochromator consisting of two channel-cut Si(111) crystals placed between the secondary source and KB-mirrors allows for easy changes between white-beam and monochromatic experiments while maintaining a fixed beam position. High resolution stage scans are performed while recording a fluorescence emission signal or an x-ray diffraction signal coming from either a monochromatic or a white focused beam. The former allows for elemental mapping, whereas the latter is used to produce two-dimensional maps of crystal-phases, -orientation, -texture, and -strain/stress. Typically achieved strain resolution is in the order of 5x10(-5) strain units. Accurate sample positioning in the x-ray focus spot is achieved with a commercial laser-triangulation unit. A Si-drift detector serves as a high-energy-resolution (approximately 150 eV full width at half maximum) fluorescence detector. Fluorescence scans can be collected in continuous scan mode with up to 300 pixels/s scan speed. A charge coupled device area detector is utilized as diffraction detector. Diffraction can be performed in reflecting or transmitting geometry. Diffraction data are processed using XMAS, an in-house written software package for Laue and monochromatic microdiffraction analysis.

The next generation of synchrotrons and free electron laser facilities requires x-ray optical systems with extremely high performance, generally of diffraction limited quality. Fabrication and use of such optics requires adequate, highly accurate metrology and dedicated instrumentation. Previously, we suggested ways to improve the performance of the Long Trace Profiler (LTP), a slope measuring instrument widely used to characterize x-ray optics at long spatial wavelengths. The main way is use of a CCD detector and corresponding technique for calibration of photo-response non-uniformity [J. L. Kirschman, et al., Proceedings of SPIE 6704, 67040J (2007)]. The present work focuses on the performance and characteristics of the upgraded LTP-II at the ALS Optical Metrology Laboratory. This includes a review of the overall aspects of the design, control system, the movement and measurement regimes for the stage, and analysis of the performance by a slope measurement of a highly curved super-quality substrate with less than 0.3 microradian (rms) slope variation.

The next generation of synchrotrons and free electron laser facilities requires x-ray optical systems with extremely high performance, generally of diffraction limited quality. Fabrication and use of such optics requires adequate, highly accurate metrology and dedicated instrumentation. Previously, we suggested ways to improve the performance of the Long Trace profiler (LTP), a slope measuring instrument widely used to characterize x-ray optics at long spatial wavelengths. The main way is use of a CCD detector and corresponding technique for calibration of photo-response non-uniformity [J. L. Kirschman, et al., Proceedings of SPIE 6704, 67040J (2007)]. The present work focuses on the performance and characteristics of the upgraded LTP-II at the ALS Optical Metrology Laboratory. This includes a review of the overall aspects of the design, control system, the movement and measurement regimes for the stage, and analysis of the performance by a slope measurement of a highly curved super-quality substrate with less than 0.3 microradian (rms) slope variation.

The next generation of synchrotrons and free electron lasers requires x-ray optical systems with extremely high-performance, generally, of diffraction limited quality. Fabrication and use of such optics requires highly accurate metrology. In the present paper, we discuss a way to improve the performance of the Long Trace Profiler (LTP), a slope measuring instrument widely used at synchrotron facilities to characterize x-ray optics at high-spatial-wavelengths from approximately 2 mm to 1 m. One of the major sources of LTP systematic error is the detector. For optimal functionality, the detector has to possess the smallest possible pixel size/spacing, a fast method of shuttering, and minimal nonuniformity of pixel-to-pixel photoresponse. While the first two requirements are determined by choice of detector, the non-uniformity of photoresponse of typical detectors such as CCD cameras is around 2-3%. We describe a flat-field calibration setup specially developed for calibration of CCD camera photo-response and dark current with an accuracy of better than 0.5%. Such accuracy is adequate for use of a camera as a detector for an LTP with performance of ~0.1 microradian (rms). We also present the design details of the calibration system and results of calibration of a DALSA CCD camera used for upgrading our LTP-II instrument at the ALS Optical Metrology Laboratory.

The next generation of synchrotrons and free electron lasers require extremely high-performance x-ray optical systems for proper focusing. The necessary optics cannot be fabricated without the use of precise optical metrology instrumentation. In particular, the Long Trace Profiler (LTP) based on the pencil-beam interferometer is a valuable tool for low-spatial-frequency slope measurement with x-ray optics. The limitations of such a device are set by the amount of systematic errors and noise. A significant improvement of LTP performance was the addition of an optical reference channel, which allowed to partially account for systematic errors associated with wiggling and wobbling of the LTP carriage. However, the optical reference is affected by changing optical path length, non-homogenous optics, and air turbulence. In the present work, we experimentally investigate the questions related to the use of a precision tiltmeter as a reference channel. Dependence of the tiltmeter performance on horizontal acceleration, temperature drift, motion regime, and kinematical scheme of the translation stage has been investigated. It is shown that at an appropriate experimental arrangement, the tiltmeter provides a slope reference for the LTP system with accuracy on the level of 0.1 μrad (rms).