Systematic error control for deflectometry with iterative reconstruction

Wang, Ruiyang; Li, Dahai; Zhang, Xinwei

doi:10.1016/j.measurement.2020.108393

Cited by 21 publications

(6 citation statements)

References 23 publications

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“…where x e , y e , and z e are the coordinates of the entrance pupil center, which are the coordinates of the camera, α 2 = α 1 and β 2 = β 1 . After obtaining the camera coordinates, the reflection points coordinates can be solved using an iterative reconstruction strategy [28].…”

Section: Entrance Pupil Calibration Methods (Epcm)mentioning

confidence: 99%

Comparison of Camera Calibration and Measurement Accuracy Techniques for Phase Measuring Deflectometry

Zhang

et al. 2021

Applied Sciences

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Phase measuring deflectometry (PMD) is a competitive method for specular surface measurement that offers the advantages of a high dynamic range, non-contact process, and full field measurement; furthermore, it can also achieve high accuracy. Camera calibration is a crucial step for PMD. As a result, a method based on the calibration of the entrance pupil center is introduced in this paper. Then, our proposed approach is compared with the most popular photogrammetric method based on Zhang’s technique (PM) and Huang’s modal phase measuring deflectometry (MPMD). The calibration procedures of these three methods are described, and the measurement errors introduced by the perturbations of degrees of freedom in the PMD system are analyzed using a ray tracing technique. In the experiment, a planar window glass and an optical planar element are separately measured, and the measurement results of the use of the three methods are compared. The experimental results for the optical planar element (removing the first 6 terms of the Zernike polynomial) show that our method’s measurement accuracy reached 13.71 nm RMS and 80.50 nm PV, which is comparable to accuracy values for the interferometer.

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Section: Entrance Pupil Calibration Methods (Epcm)mentioning

confidence: 99%

Comparison of Camera Calibration and Measurement Accuracy Techniques for Phase Measuring Deflectometry

Zhang

et al. 2021

Applied Sciences

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“…A long error propagation chain from reconstruction to stitching can adversely affect stitching accuracy [26,27]. In this paper, the stitching-reconstructing strategy is employed for sub-aperture stitching.…”

Section: Sub-aperture Stitching Of Transparent Elementsmentioning

confidence: 99%

Integrated form-position measurement of large-aperture transparent elements based on stereoscopic phase measuring deflectometry

Chen,

Yang,

Lang

et al. 2024

Surf. Topogr.: Metrol. Prop.

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In the field of ultra-precision manufacturing and measurement, sub-aperture stitching is a widely employed technique for the measurement of complex optical components. Those influencing factors like system errors and numerical bias introduce notable stitching errors in the overlapped areas between sub-apertures, consequently degrading measurement accuracy. In addition, the surfaces forms, refractive indices, and positions are difficult to be specified simultaneously. In this paper, an integrated measurement method based on the stereo deflectometry is proposed, which can measure the surface form, refractive index, and relative position of large-aperture transparent components together. This method utilizes a Gaussian process regression model to decouple and predict the refractive index and relative positions of the upper and lower surfaces. Then, a robust sub-aperture stitching technique with an adaptive distance function is employed to correct the positioning errors of sub-apertures. The feasibility and effectiveness of this method are demonstrated. The final stitched surface results exhibit a measurement error of 320 nm and a thickness deviation of 28 µm.

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“…The reference surface is used as RP to calculate the slopes. The iterative reconstruction strategy is able to eliminate the limitation of the reference surface [26][27][28][29][30][31]. Specifically, Huang et al [26] improved the Southwell grid model by iteratively compensating higher-order terms.…”

Section: Introductionmentioning

confidence: 99%

“…The Delaunay triangulation is used to represent the shape of the SUT, and the Möller-Trumbore algorithm is used to find RP. Recently, Wang et al [31] proposed a new iteration strategy, which establishes a linear relation between the reconstructed surface and RP to iteratively correct the RP.…”

Section: Introductionmentioning

confidence: 99%

A deep learning-based approach to solve the height-slope ambiguity in phase measuring deflectometry

Fan¹,

Ma²,

Li³

et al. 2023

Meas. Sci. Technol.

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Phase measuring deflectometry (PMD) shows excellent performance in measuring the shape of specular surfaces. However, the existing height-slope ambiguity affects the measurement of PMD. In this paper, we propose a deep learning-based method to solve the ambiguity and reconstruct the specular surface. A neural network was built to reconstruct the surface. A set of simulation surfaces were generated using two-dimensional Legendre polynomials to train and test the network. A spherical-shaped surface was reconstructed in a simulation to evaluate the validity of the proposed method and compare our method to the state-of-the-art method. Experimental results demonstrate a 35.88% improvement in this method’s accuracy. Our method provides a great improvement in measurement accuracy.

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Systematic error control for deflectometry with iterative reconstruction

Cited by 21 publications

References 23 publications

Comparison of Camera Calibration and Measurement Accuracy Techniques for Phase Measuring Deflectometry

Comparison of Camera Calibration and Measurement Accuracy Techniques for Phase Measuring Deflectometry

Integrated form-position measurement of large-aperture transparent elements based on stereoscopic phase measuring deflectometry

A deep learning-based approach to solve the height-slope ambiguity in phase measuring deflectometry

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