Grating metrology for X-ray and V-UV synchrotron beamlines at SOLEIL

Thomasset, Muriel; Dvorak, Joseph; Brochet, Sylvain; Dennetière, D.; Polack, F.

doi:10.1063/1.5055284

Cited by 9 publications

(14 citation statements)

References 14 publications

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“…For a long time, the preferred tool for grating characterization at synchrotron radiation facilities [4,5,[13][14][15] has been surface-slope-measuring long trace profilers (LTPs), arranged in the Littrow configuration for one dimensional (1D) measurements of the diffraction angle variation. In many cases, LTP metrology is capable of measuring groove density distributions with the required accuracy, but, due to low spatial resolution, fails to measure groove phase coherence, which determines the beamline spectral resolution achievable with the grating.…”

Section: Long Trace Profiler Ltp-ii Based Metrology Of X-ray Vls Diff...mentioning

confidence: 99%

Towards super-resolution interference microscopy metrology of x-ray variable-line-spacing diffraction gratings: recent developments

Rochester¹,

English

Lacey

et al. 2022

Advances in X-Ray/Euv Optics and Components XVII

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We report on recent work towards improving interference microscopy metrology of variable-line-spacing (VLS) x-ray diffraction gratings through a combination of techniques: image reconstruction to correct for distortion and blurring, multi-image super-resolution data acquisition to increase resolution beyond the single-image limit, and image stitching to increase the measurement area. Here, we concentrate on precision characterization and correction for lens distortion (aka geometrical distortion) and provide precise measurements of the effective image pixel distribution. We present and analyze the results of geometrical distortion measurements performed with test samples, including traditional checkerboard test artifacts and binary pseudo-random array (BPRA) standards patterned with two-dimensional uniformly redundant arrays (URA). The URA BPRA standards are also useful for measurement of the instrument transfer function (ITF), a measure of the optical aberrations and limited lateral resolution of the instrument. We also outline other essential elements and the next steps of the project on development of so-called super-resolution interference microscopy, enabling more precise measurements of VLS groove density than previously possible. The global aim of this project is to integrate our metrology technique into the manufacture of high-resolution x-ray gratings.

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Section: Long Trace Profiler Ltp-ii Based Metrology Of X-ray Vls Diff...mentioning

confidence: 99%

Towards super-resolution interference microscopy metrology of x-ray variable-line-spacing diffraction gratings: recent developments

Rochester¹,

English

Lacey

et al. 2022

Advances in X-Ray/Euv Optics and Components XVII

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“…11492 114920D-5 Let us first confirm the sign of the surface slope error contribution to the incidence angle, defined in Eqs. ( 4) and (5). Assuming that the local surface slope error is positive, then the local normal to the surface is rotated counterclockwise (refer to Fig.…”

Section: Experimental Arrangement and Procedures For Measurementsmentioning

confidence: 99%

“…The upgrade has enabled us to reliably characterize the lateral variation of groove density of variable-line-spacing (VLS) x-ray diffraction gratings in the manner discussed, for example, in Refs. [4][5][6].…”

Section: Introductionmentioning

confidence: 99%

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Characterization of groove density variation of VLS gratings with ALS XROL LTP-II in different operation modes

Lacey

Yashchuk

2020

Advances in Metrology for X-Ray and EUV Optics IX

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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.

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“…Several ingenious techniques and methods have been developed for the calibration of the pitches of standard gratings, and some of them can also be applied to the evaluation of a planar VLS grating. Critical-dimension atomic force microscopes or scanning electron microscopes can be used to assess the pitch variation of a grating [ 15 , 16 , 17 , 18 ]. However, it is not practical to measure VLS gratings in the 100 mm class due to the limited measurement throughputs and measurement ranges of these instruments.…”

Section: Introductionmentioning

confidence: 99%

Self-Calibration of a Large-Scale Variable-Line-Spacing Grating for an Absolute Optical Encoder by Differencing Spatially Shifted Phase Maps from a Fizeau Interferometer

Xiong

Yin

Quan

et al. 2022

Sensors

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A new method based on the interferometric pseudo-lateral-shearing method is proposed to evaluate the pitch variation of a large-scale planar variable-line-spacing (VLS) grating. In the method, wavefronts of the first-order diffracted beams from a planar VLS grating are measured by a commercial Fizeau form interferometer. By utilizing the differential wavefront of the first-order diffracted beam before and after the small lateral shift of the VLS grating, the pitch variation of the VLS grating can be evaluated. Meanwhile, additional positioning errors of the grating in the lateral shifting process could degrade the measurement accuracy of the pitch variation. To address the issue, the technique referred to as the reference plane technique is also introduced, where the least squares planes in the wavefronts of the first-order diffracted beams are employed to reduce the influences of the additional positioning errors of the VLS grating. The proposed method can also reduce the influence of the out-of-flatness of the reference flat in the Fizeau interferometer by taking the difference between the measured positive and negative diffracted wavefronts; namely, self-calibration can be accomplished. After the theoretical analysis and simulations, experiments are carried out with a large-scale VLS grating to verify the feasibility of the proposed methods. Furthermore, the evaluated VLS parameters are verified by comparing them with the readout signal of an absolute surface encoder employing the evaluated VLS grating as the scale for measurement.

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Grating metrology for X-ray and V-UV synchrotron beamlines at SOLEIL

Cited by 9 publications

References 14 publications

Towards super-resolution interference microscopy metrology of x-ray variable-line-spacing diffraction gratings: recent developments

Towards super-resolution interference microscopy metrology of x-ray variable-line-spacing diffraction gratings: recent developments

Characterization of groove density variation of VLS gratings with ALS XROL LTP-II in different operation modes

Self-Calibration of a Large-Scale Variable-Line-Spacing Grating for an Absolute Optical Encoder by Differencing Spatially Shifted Phase Maps from a Fizeau Interferometer

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