Stitching methods at the European Synchrotron Radiation Facility (ESRF)

Vivo, Amparo; Lantelme, B.; Baker, R.; Barrett, R.

doi:10.1063/1.4950745

Cited by 20 publications

(7 citation statements)

References 20 publications

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“…1) and the Fizeau interferometer is moved with a linear stage. Moving the interferometer and not the surface, as in other stitching setups [5,6,20,21,25], has some advantages when measuring mirrors installed in benders (a common practice in our lab). (i) The weight supported by the stage is always the same (38 kg for Zygo Verifire HD 4").…”

Section: Linear Stagementioning

confidence: 99%

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The stitching interferometry system of ALBA

Alsinet

Šics

Ribó

et al. 2023

EUV and X-Ray Optics: Synergy Between Laboratory and Space VIII

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We present the stitching interferometry system of ALBA. It has been designed for measuring the surface of long X-ray optics (up to 1.5 meters) with sub-nanometer accuracy, thanks to effectively removing the systematic errors introduced by the flat reference. We discuss the main features and measurement routines of our setup, including the aspects related to error removal. The instrument is based on a Fizeau interferometer, Zygo Verifire HD, with a 100 mm aperture, which is used to take different sub-aperture measurements. The interferometer is mounted on top of an in-house built scanning and positioning stage with four degrees of freedom: horizontal displacement, vertical displacement, yaw rotation, and roll rotation. These four degrees of freedom are essential for obtaining sub-nanometer accuracies. Horizontal and vertical displacements are needed to remove ambiguities in the surface reconstruction, and yaw and roll rotations are required to always align the interferometer to each sub-aperture to minimize retracing errors. The relative orientation between the optical bench and the interferometer platform, which comprises all three orientation angles, is measured by an external autocollimator and two inclinometers. Tracking the interferometer trajectory allows us to remove the guidance errors and solve curvature and twist ambiguities. All the stitching acquisition process is automatized. We finally show the first commissioning results and we discuss the factors that limit the current accuracy of our system. In the first results, we have reconstructed the reference flat with a repeatability of 50 picometers rms.

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Section: Linear Stagementioning

confidence: 99%

“…The surface topography of mirrors is commonly measured with wavefront interferometry techniques [1][2][3][4][5][6]. In particular, Fizeau interferometers are the most widespread system used to measure large aperture optics [3][4][5][6]. Interferometers measure the difference between the surface under test and a reference surface.…”

Section: Introductionmentioning

confidence: 99%

The stitching interferometry system of ALBA

Alsinet

Šics

Ribó

et al. 2023

EUV and X-Ray Optics: Synergy Between Laboratory and Space VIII

View full text Add to dashboard Cite

show abstract

“…The subaperture stitching with a Fizeau interferometer was demonstrated on a 400 mm long mirror with slope errors below 0.2 μrad RMS at the European Synchrotron Radiation Facility in 2015. [ 222 ] A slope‐based system capable of measuring the surface slope map was developed by stitching the subaperture slope measurements from a Hartmann–Shack sensor calibrated to accuracy higher than λ /1000 RMS. [ 223 ] The measurement accuracy is still to be verified for strongly curved surfaces.…”

Section: Single‐point‐probe‐based Profilometrymentioning

confidence: 99%

Measurement of Freeform Optical Surfaces: Trade‐Off between Accuracy and Dynamic Range

Chen

Xue

Zhai

et al. 2020

Laser & Photonics Reviews

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Freeform optical surfaces are advantageous to optical designers, as they provide additional degrees of freedom for optimization. The loss of rotational symmetry, however, makes measurement of freeforms more challenging. Herein, advances in interferometric areal measurement of freeform optical surfaces, including null tests, non-null tests, near-null tests, and adaptive null tests, are reviewed. Some new developments, in the Hartmann test, deflectometry, and phase retrieval, as representatives of non-interferometric areal measurement, are then presented. Overall, the focus is on single-point-probe-based profilometry categorized into coordinate measurements and slope-or curvature-based measurements. Innovative measurement technology is trying to bridge the gap between high accuracy and high dynamic range as freeform optical surfaces are finding more applications in visible and shorter-wavelength optics.

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“…x) dimension (100 mm to 1 m) than its sagittal (i.e. y) dimension (5 to 20 mm), stitching interferometry (SI) techniques (Mimura et al, 2005;Yumoto et al, 2016;Vivo et al, 2016;Huang et al, 2019;Huang, Wang, Tayabaly et al, 2020) have been developed to extend the field of view. The main idea is to combine the measurements in individual small fields of view to generate a height map of the entire clear aperture (CA) on the mirror surface.…”

Section: Introductionmentioning

confidence: 99%

Hybrid height and slope figuring method for grazing-incidence reflective optics

Wang¹,

Huang²,

Ke³

et al. 2023

J Synchrotron Rad

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Grazing-incidence reflective optics are commonly used in synchrotron radiation and free-electron laser facilities to transport and focus the emitted X-ray beams. To preserve the imaging capability at the diffraction limit, the fabrication of these optics requires precise control of both the residual height and slope errors. However, all the surface figuring methods are height based, lacking the explicit control of surface slopes. Although our preliminary work demonstrated a one-dimensional (1D) slope-based figuring model, its 2D extension is not straightforward. In this study, a novel 2D slope-based figuring method is proposed, which employs an alternating objective optimization on the slopes in the x- and y-directions directly. An analytical simulation revealed that the slope-based method achieved smaller residual slope errors than the height-based method, while the height-based method achieved smaller residual height errors than the slope-based method. Therefore, a hybrid height and slope figuring method was proposed to further enable explicit control of both the height and slopes according to the final mirror specifications. An experiment to finish an elliptical-cylindrical mirror using the hybrid method with ion beam figuring was then performed. Both the residual height and slope errors converged below the specified threshold values, which verified the feasibility and effectiveness of the proposed ideas.

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Stitching methods at the European Synchrotron Radiation Facility (ESRF)

Cited by 20 publications

References 20 publications

The stitching interferometry system of ALBA

The stitching interferometry system of ALBA

Measurement of Freeform Optical Surfaces: Trade‐Off between Accuracy and Dynamic Range

Hybrid height and slope figuring method for grazing-incidence reflective optics

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