Advanced environmental control as a key component in the development of ultrahigh accuracy<i>ex situ</i>metrology for x-ray optics

Yashchuk, Valeriy V.; Artemiev, Nikolay A.; Lacey, Ian; McKinney, Wayne R.; Padmore, H. A.

doi:10.1117/1.oe.54.10.104104

“…30 The DLTP is capable of slope metrology for plane surfaces with absolute error better than 80 nrad and rms error <50 nrad. 31,32 The overall error of the used data is estimated to be <60 nrad (rms). The best-fit slope trace, shown in Fig.…”

Section: Verification Of the Developed Algorithm For Identification Omentioning

confidence: 99%

Modeling of surface metrology of state-of-the-art x-ray mirrors as a result of stochastic polishing process

Yashchuk

¹

,

Tyurin²,

Tyurina³

2016

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of surface metrology of state-of-theart x-ray mirrors as a result of stochastic polishing process," Opt. Eng. 55 (7) Abstract. The design and evaluation of the expected performance of optical systems requires sophisticated and reliable information about the surface topography of planned optical elements before they are fabricated. The problem is especially severe in the case of x-ray optics for modern diffraction-limited-electron-ring and free-electron-laser x-ray facilities, as well as x-ray astrophysics missions, such as the X-ray Surveyor under development. Modern x-ray source facilities are reliant upon the availability of optics of unprecedented quality, with surface slope accuracy <0.1 μrad. The unprecedented high angular resolution and throughput of future x-ray space observatories require high-quality optics of 100 m 2 in total area. The uniqueness of the optics and limited number of proficient vendors make the fabrication extremely time-consuming and expensive, mostly due to the limitations in accuracy and measurement rate of metrology used in fabrication. We continue investigating the possibility of improving metrology efficiency via comprehensive statistical treatment of a compact volume of metrology of surface topography, which is considered the result of a stochastic polishing process. We suggest, verify, and discuss an analytical algorithm for identification of an optimal symmetric time-invariant linear filter model with a minimum number of parameters and smallest residual error. If successful, the modeling could provide feedback to deterministic polishing processes, avoiding time-consuming, whole-scale metrology measurements over the entire optical surface with the resolution required to cover the entire desired spatial frequency range. The modeling also allows forecasting of metrology data for optics made by the same vendor and technology. The forecast data are vital for reliable specification for optical fabrication, evaluated from numerical simulation to be exactly adequate for the required system performance, avoiding both over-and underspecification.

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“…30 The DLTP is capable of slope metrology for plane surfaces with absolute error better than 80 nrad and rms error <50 nrad. 31,32 The overall error of the used data is estimated to be <60 nrad (rms).…”

Section: 2]mentioning

confidence: 99%

Modeling of surface metrology of state-of-the-art x-ray mirrors as a result of stochastic polishing process

Yashchuk

¹

,

Tyurin

²

,

Tyurina³

2015

Self Cite

View full text Add to dashboard Cite

of surface metrology of state-of-theart x-ray mirrors as a result of stochastic polishing process," Opt. Eng. 55 (7) Abstract. The design and evaluation of the expected performance of optical systems requires sophisticated and reliable information about the surface topography of planned optical elements before they are fabricated. The problem is especially severe in the case of x-ray optics for modern diffraction-limited-electron-ring and free-electron-laser x-ray facilities, as well as x-ray astrophysics missions, such as the X-ray Surveyor under development. Modern x-ray source facilities are reliant upon the availability of optics of unprecedented quality, with surface slope accuracy <0.1 μrad. The unprecedented high angular resolution and throughput of future x-ray space observatories require high-quality optics of 100 m 2 in total area. The uniqueness of the optics and limited number of proficient vendors make the fabrication extremely time-consuming and expensive, mostly due to the limitations in accuracy and measurement rate of metrology used in fabrication. We continue investigating the possibility of improving metrology efficiency via comprehensive statistical treatment of a compact volume of metrology of surface topography, which is considered the result of a stochastic polishing process. We suggest, verify, and discuss an analytical algorithm for identification of an optimal symmetric time-invariant linear filter model with a minimum number of parameters and smallest residual error. If successful, the modeling could provide feedback to deterministic polishing processes, avoiding time-consuming, whole-scale metrology measurements over the entire optical surface with the resolution required to cover the entire desired spatial frequency range. The modeling also allows forecasting of metrology data for optics made by the same vendor and technology. The forecast data are vital for reliable specification for optical fabrication, evaluated from numerical simulation to be exactly adequate for the required system performance, avoiding both over-and underspecification.

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“…12,27,[37][38][39][40][41] This can be thought of as a repeatability ( Below we describe a custom-made tilt stage Model N-310K021 designed and manufactured at Physik…”

Section: Design and Compliance Tests Of A Tilt Stage For A Utm Smentioning

confidence: 99%

“…Practically, the high frequency systematic errors in measurements with strongly curved x-ray optics can be suppressed to a level below 0.25 rad (rms). 27,28 The other group of systematic errors relates to the uncertainty of the instrumental calibration, corresponding to relatively lower spatial frequencies. In an LTP, such an error appears as unaccounted nonlinearity of the position-toslope conversion factor, e.g., due to aberration of the Fourier transform lens or slight out-of-focus position of the CCD detector.…”

Section: Introductionmentioning

confidence: 99%

High precision tilt stage as a key element to a universal test mirror for characterization and calibration of slope measuring instruments

Yashchuk

¹

,

Artemiev

²

,

Centers

³

et al. 2016

Review of Scientific Instruments

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The ultimate performance of surface slope metrology instrumentation, such as long trace profilers and autocollimator based deflectometers, is limited by systematic errors that are increased when the entire angular range is used for metrology of significantly curved optics. At the ALS X-Ray Optics Laboratory, in collaboration with the HZB/BESSY-II and PTB (Germany) metrology teams, we are working on a calibration method for deflectometers, based on a concept of a universal test mirror (UTM) [Proc. SPIE 6704, 67040A (2007)]. Potentially, the UTM method provides high performance calibration, and accounts for peculiarities of the optics under test (e.g., slope distribution) and the experimental arrangement (e.g., the distance between the sensor and the optic under test). At the same time, the UTM calibration method is inherently universal, applicable to a variety of optics and experimental arrangements. In this work we present the results of tests with a key component of the UTM system, a custom high precision tilt stage, which has been recently developed in collaboration with Physik Instrumente, a Author to whom correspondence should be addressed. Electronic mail: VVYashchuk@lbl.gov. 2GmbH. The tests have demonstrated high performance of the stage and its capability (after additional calibration) to provide angular calibration of surface slope measuring profilers over the entire instrumental dynamic range with absolute accuracy better than 30 nrad. The details of the stage design and tests are presented. We also discuss the foundation of the UTM method and calibration algorithm, as well as the possible design of a full scale UTM system.

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Advanced environmental control as a key component in the development of ultrahigh accuracyex situmetrology for x-ray optics

Cited by 36 publications

References 63 publications

Modeling of surface metrology of state-of-the-art x-ray mirrors as a result of stochastic polishing process

Modeling of surface metrology of state-of-the-art x-ray mirrors as a result of stochastic polishing process

Modeling of surface metrology of state-of-the-art x-ray mirrors as a result of stochastic polishing process

High precision tilt stage as a key element to a universal test mirror for characterization and calibration of slope measuring instruments

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