Dr. Zhenkun Lei Profile

KEYWORDS: Deformation, Digital image correlation, Materials properties, Algorithm development, Analytical research, Transform theory, Image processing, Engineering, Aerospace engineering, Absorption

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Proceedings Article | 4 November 2024 Paper

Study on 3D-RVE multiphysics model of carbon fiber electrode

Xiaoyu Liu, Junjie Zhong, Xiaochen Wang, Zhenkun Lei, Ruixiang Bai

Proceedings Volume 13420, 1342009 (2024) https://doi.org/10.1117/12.3054954

KEYWORDS: Carbon fibers, Electrodes, 3D modeling, Lithium, Ions, Electrolytes, Porosity, Motion models, Diffusion, Batteries

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Proceedings Article | 17 April 2020 Paper

Comparative study on double-step phase-shifting algorithm for nonlinear phase error compensation

Canlin Zhou, Zhenkun Lei, XiaoLei Li

Proceedings Volume 11455, 114553F (2020) https://doi.org/10.1117/12.2564637

KEYWORDS: Phase shifts, Fringe analysis, Error analysis, Phase shifting, 3D metrology, Phase measurement, Cameras, Calibration

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The phase-shifting method is widely used in fringe projection profilometry (FPP),The digital light projector (DLP) and charge coupled device (CCD) are generally nonlinear devices.The captured fringes do not have a good sinusoidal property,which leads to errors in the retrieved phase map.The methods to calibrate the nonlinear response of a FPP and compensate for the associated error can be classified into active methods(correction before pattern projection) and passive methods(correction after pattern projection).The basic idea of the active method to precisely obtain the input output relation function of the projector. The passive method compensates the error in phase domain by the post-processing algorithms. Huang et. al. presented the double three-step phase shifting algorithm to reduce the nonlinear phase error by projecting two groups of three-step phase-shifting fringe with an initial phase offset of 60 degree.Subsequently,some scholars improved this method. Zheng et.al. presented a method that combined the two wrapped phases to obtain the combination of the wrapped phase,it is simpler than Huang’s method because only one time phase unwrapping procedure is needed. Lei et. al. combined double-step phase-shifting method and multifrequency temporal phase unwrapping algorithm, proposed a multi-frequency inverse-phase method to realize the 3D shape measurement of the complicated objects. Mao proposed a similar approach.The main difference between Lei and Mao is that the operation order of double-step phase-shifting algorithm for error compensation is different. In Mao’s method,error compensation is performed in the wrapped phase map while it is done with the unwrapped phase map in Lei’s method.This paper compares double-step phase-shifting algorithm, its variational algorithm (Zheng's method, Lei’ s method, Mao's method) and phase shift algorithm with twice the number of steps for nonlinear error compensation, our study finds that these algorithms have similar effect in reducing nonlinear phase error. Phase shift algorithm with twice the number of steps is simpler and more direct than double-step phase-shifting algorithm.In variational algorithm, Zheng’s method reduces the number of phase unwrapping by half compared with traditional double-step phase shifting algorithm,Mao’s method is essentially the same as Lei’s method,it was by introducing multi-frequency temporal phase unwrapping algorithm that Lei and Mao's method can measure the complex object. Experimental results are presented to demonstrate the rationality of this analysis.

SPIE Journal Paper | 11 April 2020

Image encryption algorithm based on gradient decomposition and improved logistic map

Guangbiao Ma, Chen Tang, Mingming Chen, Zhenkun Lei

JEI, Vol. 29, Issue 02, 023023, (April 2020) https://doi.org/10.1117/12.10.1117/1.JEI.29.2.023023

KEYWORDS: Image encryption, Image processing, Complex systems, Image restoration, Binary data, Chaos, Image information entropy, Gyrators, Computer security, Matrices

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Proceedings Article | 20 December 2019 Paper

Robust weighted least-squares phase-unwrapping algorithm

Canlin Zhou, Shuchun Si, XiaoLei Li, Zhenkun Lei, YanJie Li

Proceedings Volume 11209, 112091U (2019) https://doi.org/10.1117/12.2547663

KEYWORDS: Reliability, Fringe analysis, Algorithm development, Cameras, Phase measurement, Physics, Mechanics, Phase shifting

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Proceedings Article | 20 December 2019 Paper

One-shot common-path phase-shifting holography based on micropolarizer camera and large-shearing Wollaston Prism

Canlin Zhou, Shuchun Si, XiaoLei Li, Zhenkun Lei, YanJie Li

Proceedings Volume 11209, 112091W (2019) https://doi.org/10.1117/12.2547690

KEYWORDS: Holograms, Digital holography, Phase shifts, Cameras, Prisms, Holography, Polarization, 3D image reconstruction, Beam splitters, Image processing

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SPIE Journal Paper | 12 February 2019 Open Access

Fully automated extraction of the fringe skeletons in dynamic electronic speckle pattern interferometry using a U-Net convolutional neural network

Biyuan Li, Chen Tang, Tingyue Zheng, Zhenkun Lei

OE, Vol. 58, Issue 02, 023105, (February 2019) https://doi.org/10.1117/12.10.1117/1.OE.58.2.023105

KEYWORDS: Fringe analysis, Speckle pattern, Interferometry, Image processing, Convolutional neural networks, Artificial intelligence, Optical engineering, Network architectures, Lithium, Palladium

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Proceedings Article | 24 July 2018 Paper

Simple tilt compensation algorithm for off-axis digital holography

Canlin Zhou, XiaoLei Li, Shuchun Si, Zhenkun Lei, YanJie Li

Proceedings Volume 10827, 108270Q (2018) https://doi.org/10.1117/12.2500462

KEYWORDS: Holograms, Fourier transforms, Digital holography, Computer simulations, Phase measurement, Microscopes, Fringe analysis

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Proceedings Article | 24 July 2018 Paper

Modified Fourier transform profilometry based on digital time-multiplexing technique

Canlin Zhou, XiaoLei Li, Shuchun Si, Zhenkun Lei, YanJie Li

Proceedings Volume 10827, 108271S (2018) https://doi.org/10.1117/12.2500390

KEYWORDS: Fringe analysis, Fourier transforms, Phase shifting, 3D metrology, Projection systems, Cameras, Digital filtering, Computer simulations, CCD cameras

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Proceedings Article | 21 August 2014 Paper

Calibration of elasto-optic constant in digital gradient sensing method

Zhenkun Lei, Xuan Li, Fangxu Zhang

Proceedings Volume 9233, 92330F (2014) https://doi.org/10.1117/12.2068802

KEYWORDS: Calibration, Polymethylmethacrylate, Speckle, Mechanical sensors, Digital image correlation, Charge-coupled devices, Mechanics, Optical testing, Image processing, Image acquisition

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Proceedings Article | 21 August 2014 Paper

FPGA implementation of 3D-displacement measurement based on 2D-DIC and FPP

Zhenkun Lei, Fangxu Zhang, Xuan Li

Proceedings Volume 9233, 923304 (2014) https://doi.org/10.1117/12.2069992

KEYWORDS: Field programmable gate arrays, Fringe analysis, Ions, Cameras, 3D metrology, Projection systems, Digital image correlation, Computer programming, 3D image processing, LabVIEW

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Proceedings Article | 10 February 2005 Paper

A method with exact phase-shifting values and its experimental techniques in shadow moiré topography

Hai Yun, Dazhen Yun, Zhenkun Lei

Proceedings Volume 5638, (2005) https://doi.org/10.1117/12.575090

KEYWORDS: Phase shifts, Optical spheres, Moire patterns, Light sources, Neptunium, Virtual reality, 3D modeling, Image processing, Cameras, 3D image processing

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Proceedings Article | 30 December 2004 Paper

Origin mechanism of residual stresses in porous silicon film

Zhenkun Lei, Yilan Kang, Ming Hu, Yu Qiu, Hao Cen

Proceedings Volume 5641, (2004) https://doi.org/10.1117/12.574579

KEYWORDS: Picosecond phenomena, Silicon, Capillaries, Silicon films, Interfaces, X-ray diffraction, Liquids, Atomic force microscopy, Micro raman spectroscopy, Oxidation

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