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High-dynamic-range 3D shape measurement based on time domain superposition

MEASUREMENT SCIENCE AND TECHNOLOGY 2019年第6期30卷 065004-065004页

作者： Zhang, Liang Chen, Qian Zuo, Chao Tao, Tianyang Zhang, Yuzhen Feng, Shijie Nanjing Univ Sci & Technol Jiangsu Key Lab Spectral Imaging & Intelligent Se Nanjing 210094 Jiangsu Peoples R China Nanjing Univ Sci & Technol Smart Computat Imaging SCI Lab Nanjing 210094 Jiangsu Peoples R China

Fringe projection is a widely used approach for 3D shape measurements. However, it is ineffective for scenarios with a wide range of reflectivity. In this paper, we propose a technique that can measure high-dynamic-range surfaces without changing camera exposure or projected light intensity. With the strategy of time domain superposition, we can use noisy fringe images to recover phase and geometric shapes accurately for low-reflection and high-reflection regions. The measurement accuracy of low-reflection regions obtained by the proposed method is about three times higher than that of the traditional phase-shifting method. Both simulations and experiments are performed to verify the proposed method.

关键词： fringe projection profilometry phase-shifting algorithm high dynamic range 3D reconstruction time domain superposition

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Fast and robust online three-dimensional measurement based on feature correspondence

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OPTICAL ENGINEERING 2021年第7期60卷 074101-074101页

作者： Wu, Haitao Cao, Yiping An, Haihua Li, Yang Li, Hongmei Xu, Cai Sichuan Univ Dept Optoelect Chengdu Sichuan Peoples R China East China Univ Technol Sch Sci Nanchang Jiangxi Peoples R China Chengdu Normal Univ Coll Phys & Engn Chengdu Sichuan Peoples R China

Online three-dimensional (3D) measurement plays an important role in industry. When phase-shifting profilometry is employed in online 3D measurement, pixel matching is an important step to keep objects at the same coordinate value. However, the correlation operation and marker feature matching algorithms may take a long time, increasing the complexity. So a fast and robust online 3D measurement based on feature correspondence is proposed. In this method, only one frame of the sinusoidal fringe pattern is projected onto the measured object, and image correction technique is employed to rectify pixel size. Then five frames of deformed patterns with equivalent displacement are captured by the camera, and the corresponding modulation patterns are extracted. The oriented fast and rotated brief feature algorithm is used to extract the matching pair of feature points, and the improved grid-based motion statistical feature algorithm can better eliminate the false match to achieve pixel matching. In this way, five frames of deformed patterns with an equivalent shifted-phase can be extracted. Finally, the 3D shape of the measured object is reconstructed by the five-step equivalent phase-shifting algorithm. Experimental results verify the effectiveness and feasibility of the proposed method. (C) 2021 Society of Photo-Optical Instrumentation Engineers (SPIE)

关键词： three-dimensional measurement online measurement pixel matching modulation feature correspondence phase-shifting algorithm

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Quantum imaging beyond the standard-quantum limit and phase distillation

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NEW JOURNAL OF PHYSICS 2024年第2期26卷 023018页

作者： Schaffrath, Simon Derr, Daniel Graefe, Markus Giese, Enno Tech Univ Darmstadt Inst Angew Phys Fachbereich Phys Schlossgartenstr 7 D-64289 Darmstadt Germany Fraunhofer Inst Appl Opt & Precis Engn IOF Albert Einstein Str 7 D-07745 Jena Germany Leibniz Univ Hannover Inst Quantenoptik Welfengarten 1 D-30167 Hannover Germany

Quantum sensing using non-linear interferometers (NLIs) offers the possibility of bicolour imaging, using light that never interacted with the object of interest, and provides a way to achieve phase supersensitivity, i.e. a Heisenberg-type scaling of the phase uncertainty. Such a scaling behaviour is extremely susceptible to noise and only arises at specific phases that define the optimal working point (WP) of the device. While phase-shifting algorithms are to some degree robust against the deleterious effects induced by noise they extract an image by tuning the interferometer phase over a broad range, implying an operation beyond the WP. In our theoretical study, we investigate both the spontaneous and the high-gain regime of operation of an NLI. In fact, in the spontaneous regime using a distillation technique and operating at the WP leads to a qualitatively similar behaviour. In the high-gain regime, however, typical distillation techniques inherently forbid a scaling better than the standard-quantum limit, as a consequence of the photon statistics of squeezed vacuum. In contrast, an operation at the WP still may lead to a sensitivity below shot noise, even in the presence of noise. Therefore, this procedure opens the perspective of bicolour imaging with a better than shot-noise phase uncertainty by working in the vicinity of the WP. Our results transfer quantum imaging distillation in a noisy environment to the high-gain regime with the ultimate goal of harnessing its full potential by combining bicolour imaging and phase supersensitivity.

关键词： quantum imaging quantum metrology supersensitivity squeezing phase-shifting algorithm non-linear interferometer standard quantum limit

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(3 N+1)-frame phase retrieval for double-grating Ronchi lateral shearing interferometry

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OPTICS AND LASERS IN ENGINEERING 2022年 158卷

作者： Lu, Yunjun Tang, Feng Su, Rong Li, Zhongliang Guo, Fudong Feng, Peng Wang, Xiangzhao Chinese Acad Sci Shanghai Inst Opt & Fine Mech Shanghai 201800 Peoples R China Univ Chinese Acad Sci Ctr Mat Sci & Optoelect Engn Beijing 100049 Peoples R China

Accurate wavefront measurement using double-grating Ronchi lateral shearing interferometry significantly relies on the accuracy of shear-phase retrieval. Traditional methods cannot effectively suppress the interferences of unwanted diffractions generated by the Ronchi grating at the image plane. In this paper, we propose a method that uses 3 N + 1 shear interferograms to retrieve the shear phase, where N is a positive integer. The selection of N depends on the number of the diffraction orders existing in the shearogram. According to the numerical aperture of the optical system under test and the period of image grating, the interferograms corresponding to the specific 3 N + 1 phase shifts are obtained, from which the shear phase is calculated. For validation, the frequency response of the proposed algorithm is characterized, and the improved accuracy of wavefront measurement is demonstrated by comparisons with the existing 8-frame, 10-frame and 13-frame methods.

关键词： Ronchi lateral shearing interferometry Wavefront metrology phase retrieval phase-shifting algorithm Frequency transfer function

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phase reconstruction by phase shift estimation with reliable parameter minimization

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METROLOGIA 2024年第5期61卷

作者： Zhang, Yu Liu, Bao Northeast Elect Power Univ Inst Mat Phys Coll Sci Jilin 132012 Peoples R China Chinese Acad Sci Changchun Inst Opt Fine Mech & Phys Changchun 130022 Peoples R China

Achieving a balance between accuracy and speed in phase reconstruction is a challenging problem. In phase-shifting interferometry, increasing the speed by reducing the number of phase shifts while maintaining high accuracy is highly desirable. We propose an accurate and efficient two-step phase reconstruction method utilizing random phase shift. This method directly estimates the phase shift through reliable parameter minimization, allowing for easy and precise phase reconstruction. Simulations and experiments demonstrate the superior performance of our method across various scenarios, outperforming well-known two-step phase-shifting algorithms. We expect this paper to provide a general and powerful tool for phase reconstruction.

关键词： phase-shifting algorithm reliable parameter minimization phase shift accuracy

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Development of two-frame shadow moire profilometry by iterative self-tuning technique

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OPTICAL ENGINEERING 2018年第11期57卷 114101-114101页

作者： Du, Hubing Zhang, Shaofeng Zhao, Zixin Yu, Jianhong Liu, Haitao Xian Technol Univ Sch Mechatron Engn Xian Shaanxi Peoples R China Xi An Jiao Tong Univ State Key Lab Mfg Syst Engn Xian Shaanxi Peoples R China

Shadow moire fringes have a complex intensity distribution, which makes the existing arcsine function or arccosine function that is used in random phase-shift extraction algorithms unstable in applications. We propose a high-precision algorithm to determine the random phase shift in a robust way. The idea consists of constructing three consecutive fringe patterns by the addition of two background terms suppressed fringe patterns. Then, an iterative self-tuning phase-shifting algorithm is developed to extract the measurement phase in a pointwise manner. Due to the use of an iterative procedure and tangent function, the present method can evaluate the phase shift accurately and robustly and can be implemented easily in many applications. In addition, the proposed method provides a solution for the development of the two-frame random shadow moire technique. We present simulation and optical experiments to demonstrate the correctness of the proposed method. The results show that the proposed method performs better than other methods. (C) 2018 Society of Photo-Optical Instrumentation Engineers (SPIE).

关键词： phase-shifting algorithm shadow moire phase phase-shifting

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Novel absolute phase measurement method with few-patterns

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OPTICS AND LASERS IN ENGINEERING 2022年 154卷 107031-107031页

作者： Pai, Wenyan Liang, Jin Zhang, MingKai Tang, Zhengzong Li, Leigang Xi An Jiao Tong Univ State Key Lab Mfg Syst Engn Xian Peoples R China XTOP 3D Technol Shenzhen Co Ltd Innovat Lab Shenzhen Peoples R China

The temporal phase unwrapping method can obtain the absolute phase of an object with large discontinuities and isolated objects in phase measuring profilometry. But it needs many frames fringe patterns, which may consume a significant amount of time in 3D surface measurement. In the light of this problem, we proposed a novel absolute phase measurement method with few-patterns. The proposed method combines an object reflectivity correction and a half-period gray-coded phase unwrapping algorithm. One group of precoded three-step phase shifting fringe patterns are used to calculate the wrapped phase, divide the whole measurement region into many sub-regions, correct the surface reflectivity of the tested object. A frame of half-period gray-coded pattern and the index number of the sub-region are used to determine the fringe order. The proposed method can obtain a large number of codewords for fringe order without decreasing the intensity level for each stair. To verify the effectiveness of the proposed method, we measured two isolated masks and compared the result with Chen's method [1] . The result shows that the accuracy of our method is similar to Chen's method, but our method has two images less than Chen's method, which improves the measurement speed. Then we measured two complex isolated sculptures. The result shows that our method is also effective for complex surfaces.

关键词： phase-shifting algorithm 3D shape measurement Wrapped phase Half-period Gray-level phase unwrapping

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High-speed high-accuracy three-dimensional shape measurement using digital binary defocusing method versus sinusoidal method

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OPTICAL ENGINEERING 2017年第7期56卷 074102-074102页

作者： Hyun, Jae-Sang Li, Beiwen Zhang, Song Purdue Univ Sch Mech Engn W Lafayette IN 47907 USA

This paper presents our research findings on high-speed high-accuracy three-dimensional shape measurement using digital light processing (DLP) technologies. In particular, we compare two different sinusoidal fringe generation techniques using the DLP projection devices: direct projection of computer-generated 8-bit sinusoidal patterns (a.k.a., the sinusoidal method), and the creation of sinusoidal patterns by defocusing binary patterns (a.k.a., the binary defocusing method). This paper mainly examines their performance on high-accuracy measurement applications under precisely controlled settings. Two different projection systems were tested in this study: a commercially available inexpensive projector and the DLP development kit. Experimental results demonstrated that the binary defocusing method always outperforms the sinusoidal method if a sufficient number of phase-shifted fringe patterns can be used. (C) 2017 Society of Photo-Optical Instrumentation Engineers (SPIE)

关键词： high three-dimensional optical metrology binary defocusing method phase-shifting algorithm fringe analysis structured light

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Reconstruction-free fast depth segmentation via temporal orthogonal frequency fringe patterns

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OPTICS AND LASER TECHNOLOGY 2021年 137卷 106803-106803页

作者： Deng, Ji Li, Jian Feng, Hao Xiao, Yu Ding, Shumeng Han, Wenzhong Zeng, Zhoumo Tianjin Univ Sch Precis Instrument & Optoelect Engn State Key Lab Precis Measurement Technol & Instru 92 Weijin Rd Tianjin 300072 Peoples R China North China Inst Aerosp Engn Sch Mech & Elect Engn 133 Aimin East Rd Langfang 065000 Peoples R China

In many machine vision techniques, depth segmentation is a central process to segment targeted objects with abruptly changing depth into different regions for 3D data analysis. However, current techniques are limited by data-acquisition speed, computational cost, and the precision of segmentation. To overcome these challenges, this paper proposes a dynamic depth-segmentation technique that allows the segmentation of target objects into isolated depth regions without requiring three-dimensional reconstruction and background removal. Taking full advantage of the merits of the phase-shifting algorithm, singular-points theory about depth segmentation is summarized and applied to extract the segmenting lines as the markers for depth segmentation. Meanwhile, by using the proposed temporal orthogonal frequency scheme, the dynamic performance and the high-frequency components of the measured objects are both guaranteed during the computing process. Finally, a low-cost morphology-based optimization is created to solve the over-segmentation problem and enlarge the measurable dynamic range. The simulation result demonstrates the segmentation accuracy of this technique. Experimental results on objects of differing status show that the proposed approach provides satisfactory omnidirectional depth-segmentation results with high accuracy and fidelity.

关键词： Depth segmentation phase-shifting algorithm Singular-points theory Reconstruction-free

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Precision Interferometric Thickness Profiling of a Transparent Plate Using a phase-Extraction algorithm Suppressing Refractive-Index Dispersion

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TRANSACTIONS OF THE KOREAN SOCIETY OF MECHANICAL ENGINEERS A 2022年第5期46卷 435-443页

作者： Jeon, Jurim Kim, Sungtae Kim, Yangjin Pusan Natl Univ Sch Mech Engn Busan South Korea

Wavelength tuning interferometry has been widely used to measure the optical thickness variation of a transparent plate. In the wavelength tuning technique, interference signals can be distinguished by detecting the modulation frequencies of interference signals. Because the modulation frequencies are proportional to the optical path difference, the necessary information about the optical thickness can be obtained via wavelength tuning. However, the refractive-index dispersion of the transparent plate and nonlinearity of the wavelength-tuning can result in a modulation frequency shift. In this study, a novel 21-sample phase-shifting algorithm that can suppress the effects of the refractive index dispersion and nonlinearity was derived using a Fourier analysis in the frequency domain. The characteristics of the proposed algorithm were visualized in the frequency domain using a Fourier transform. Finally, the optical thickness variation was measured by the 21-sample algorithm and Fizeau interferometer.

关键词： Nonlinear Error phase-shifting algorithm Refractive-Index Dispersion Thickness Wavelength Tuning Interferometer

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