Distortion correction of a microscopy lens system for deformation measurements based on speckle pattern and grating

Qian, Wenjie; Li, Jian; Zhu, Jianguo; Hao, Wenfeng; Chen, Lei

doi:10.1016/j.optlaseng.2019.105804

Cited by 14 publications

(1 citation statement)

References 29 publications

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“…Although the distortion has a negligible effect on the surface roughness measurements, it can cause a significant misrepresentation of the SUT topography in both height and special frequency (PSD) domains (see, for example, Refs. [18][19][20][21][22][23][24][25] and references therein).…”

Section: Microscope's Geometrical Distortion and Itf Calibrationmentioning

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: Microscope's Geometrical Distortion and Itf Calibrationmentioning

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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show abstract

High-precision and Arbitrary Arranged Projection Moiré System Based on an Iterative Calculation Model and the Self-calibration Method

2021

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A Robot-Assisted Microscopy System for Digital Image Correlation in Fatigue Crack Growth Testing

2023

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Background Digital image correlation (DIC) with microscopes has become an important experimental tool in fracture mechanics to study local effects such as the plastic zone, crack closure, crack deflection or crack branching. High-resolution light microscopes provide 2D images but the field of view is limited to a small area and very sensitive to its alignment. A flexible positioning system is therefore needed to collect such DIC data during the entire fatigue crack growth process. Objective We present in our paper a new experimental setup for local high-resolution 2D DIC measurements at any location and at any time during fatigue crack growth experiments with a non-fixed DIC microscopy system. Methods We use a robot to move the 2D DIC microscope to any location on the surface of the specimen. Optical and tactile methods automatically adjust the system and ensure highest image quality as well as accurate alignment. In addition, an advanced repositioning method reduces out-of-plane motion effects. Results The robot is able to achieve a repositioning accuracy of less than 0.06 mm in vector space, resulting in very low Von Mises strain scattering of 0.07 to 0.09% in the DIC evaluation. The system minimizes systematic errors caused by translation and rotational deviations. Effects such as crack deflection, crack branching or the plastic zone of a fatigue crack can be investigated with a field of view of 10.2 x 6.4 mm2. Conclusions The robot supported DIC system generates up to 8000 high-quality DIC images in an experiment that enables the application of digital evaluation algorithms. Redundant information create confidence in the results as all revealed effects are comprehensible. This increases the information content of a single fatigue crack growth test and accelerates knowledge generation.

show abstract

Distortion correction of a microscopy lens system for deformation measurements based on speckle pattern and grating

Cited by 14 publications

References 29 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

High-precision and Arbitrary Arranged Projection Moiré System Based on an Iterative Calculation Model and the Self-calibration Method

A Robot-Assisted Microscopy System for Digital Image Correlation in Fatigue Crack Growth Testing

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