Nano-metrology: The art of measuring X-ray mirrors with slope errors &amp;lt;100 nrad

Alcock, Simon G.; Nistea, Ioana; Sawhney, Kawal

doi:10.1063/1.4949272

Cited by 17 publications

(12 citation statements)

References 18 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…An additional pair (M5b) was implemented for the high-energy range (2-3 keV). The mechanics were designed so that each of the vertical stack of mirrors could be clamped separately and any induced clamping distortions could be checked on the Diamond-NOM before installation (Alcock et al, 2010(Alcock et al, , 2016. Each vertical stack of mirrors could then be installed into the main mechanics using three bolts from the back, minimizing the risk of any damage to the optical surfaces during installation.…”

Section: The M5 Mirror Systemmentioning

confidence: 99%

I21: an advanced high-resolution resonant inelastic X-ray scattering beamline at Diamond Light Source

et al. 2022

Self Cite

View full text Add to dashboard Cite

The I21 beamline at Diamond Light Source is dedicated to advanced resonant inelastic X-ray scattering (RIXS) for probing charge, orbital, spin and lattice excitations in materials across condensed matter physics, applied sciences and chemistry. Both the beamline and the RIXS spectrometer employ divergent variable-line-spacing gratings covering a broad energy range of 280–3000 eV. A combined energy resolution of ∼35 meV (16 meV) is readily achieved at 930 eV (530 eV) owing to the optimized optics and the mechanics. Considerable efforts have been paid to the design of the entire beamline, particularly the implementation of the collection mirrors, to maximize the X-ray photon throughput. The continuous rotation of the spectrometer over 150° under ultra high vacuum and a cryogenic manipulator with six degrees of freedom allow accurate mappings of low-energy excitations from solid state materials in momentum space. Most importantly, the facility features a unique combination of the high energy resolution and the high photon throughput vital for advanced RIXS applications. Together with its stability and user friendliness, I21 has become one of the most sought after RIXS beamlines in the world.

show abstract

Section: The M5 Mirror Systemmentioning

confidence: 99%

I21: an advanced high-resolution resonant inelastic X-ray scattering beamline at Diamond Light Source

et al. 2022

Self Cite

View full text Add to dashboard Cite

show abstract

“…This environmentally stabilized laboratory contains a suite of metrology instruments capable of characterizing state-of-the-art synchrotron X-ray optics (Alcock et al, 2016). After assembly, each mirror was sequentially installed, aligned and tested on the Diamond-NOM (see Fig.…”

Section: Mechanical Bendermentioning

confidence: 99%

“…With such precautions, previous experiments have shown that the Diamond-NOM is capable of reliably measuring X-ray mirrors with slope errors < 50 nrad r.m.s. (Alcock et al, 2016). Bending motors were driven using a MCS8+ motion controller, via the Experimental Physics and Industrial Control System (EPICS), which enabled synchronization with Diamond-NOM scans also controlled via EPICS.…”

Section: Mechanical Bendermentioning

confidence: 99%

Long, elliptically bent, active X-ray mirrors with slope errors <200 nrad

Nistea

Alcock

Kristiansen³

et al. 2017

J Synchrotron Radiat

Self Cite

View full text Add to dashboard Cite

Actively bent X-ray mirrors are important components of many synchrotron and X-ray free-electron laser beamlines. A high-quality optical surface and good bending performance are essential to ensure that the X-ray beam is accurately focused. Two elliptically bent X-ray mirror systems from FMB Oxford were characterized in the optical metrology laboratory at Diamond Light Source. A comparison of Diamond-NOM slope profilometry and finite-element analysis is presented to investigate how the 900 mm-long mirrors sag under gravity, and how this deformation can be adequately compensated using a single, springloaded compensator. It is shown that two independent mechanical actuators can accurately bend the trapezoidal substrates to a range of elliptical profiles. Stateof-the-art residual slope errors of <200 nrad r.m.s. are achieved over the entire elliptical bending range. High levels of bending repeatability (ÁR/R = 0.085% and 0.156% r.m.s. for the two bending directions) and stability over 24 h (ÁR/R = 0.07% r.m.s.) provide reliable beamline performance.

show abstract

“…Pencil-beam devices, such as the long trace profiler (LTP), nanometer optical metrology (NOM), and their successive versions 11 – 17 , are widely used, simple to interpret, and able to measure X-ray mirrors up to 1.5 m long, but only along one dimension (1D) at a time. Each successive version has brought improved precision to the figure measurements, so that today’s NOM can inspect the figure of flat or weakly curved mirrors with remarkable precision: down to 50 nrad 18 – 20 . Nonetheless, despite the use of a penta-prism to keep the beam deflection independent of the slide’s pitch error, the sawtooth deviation (over 250 nrad rms) from the electronic autocollimator (AC) interferes with the NOM’s measurement of the angle of deflection of the surface under test, and special calibration should be used to minimize the sawtooth error 21 .…”

Section: Introductionmentioning

confidence: 99%

Nano-precision metrology of X-ray mirrors with laser speckle angular measurement

2021

Self Cite

View full text Add to dashboard Cite

X-ray mirrors are widely used for synchrotron radiation, free-electron lasers, and astronomical telescopes. The short wavelength and grazing incidence impose strict limits on the permissible slope error. Advanced polishing techniques have already produced mirrors with slope errors below 50 nrad root mean square (rms), but existing metrology techniques struggle to measure them. Here, we describe a laser speckle angular measurement (SAM) approach to overcome such limitations. We also demonstrate that the angular precision of slope error measurements can be pushed down to 20nrad rms by utilizing an advanced sub-pixel tracking algorithm. Furthermore, SAM allows the measurement of mirrors in two dimensions with radii of curvature as low as a few hundred millimeters. Importantly, the instrument based on SAM is compact, low-cost, and easy to integrate with most other existing X-ray mirror metrology instruments, such as the long trace profiler (LTP) and nanometer optical metrology (NOM). The proposed nanometrology method represents an important milestone and potentially opens up new possibilities to develop next-generation super-polished X-ray mirrors, which will advance the development of X-ray nanoprobes, coherence preservation, and astronomical physics.

show abstract

Nano-metrology: The art of measuring X-ray mirrors with slope errors <100 nrad

Cited by 17 publications

References 18 publications

I21: an advanced high-resolution resonant inelastic X-ray scattering beamline at Diamond Light Source

I21: an advanced high-resolution resonant inelastic X-ray scattering beamline at Diamond Light Source

Long, elliptically bent, active X-ray mirrors with slope errors <200 nrad

Nano-precision metrology of X-ray mirrors with laser speckle angular measurement

Contact Info

Product

Resources

About