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7th Asia Pacific Conference on Optics Manufacture (APCOM)

作者： Chang, Lin He, Tingting Yu, Yingjie Shanghai Univ Sch Mechatron Engn & Automat Shanghai Peoples R China

ISBN: (数字)9781510652095

ISBN: (纸本)9781510652095;9781510652088

The surface morphologies and thickness variation are the basic characteristics of a transparent parallel plate with multiple surfaces. Measurements of these profiles are greatly significant for the evaluation of surface quality. The measurement accuracy of phase-shifting interferometry can reach the nanometer level, which is an effective method for high-precision measurements of ultra-smooth surfaces. However, each measured surface will give its own harmonic to the captured interferograms, resulting in the information of harmonics mixed. Thus the surface topology information can not be detected directly, which can cause problems of the wavefront reconstruction of the measured surface. To solve this problem, separating the mixed harmonics is necessary. The fundamental difference in harmonics lies in their frequency. Therefore, determining these differences of harmonics by frequency is a preliminary method of phase demodulation.

关键词： Least Squares Multi-Surface Measurement phase-shifting algorithm Frequency Estimation

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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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Use of an interferential objective and synthetic wavelength in evaluation of biological samples

Use of an interferential objective and synthetic wavelength ...

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Optical Technology and Measurement for Industrial Applications Conference

作者： Martinez-Garcia, Amalia Hernandez-Gutierrez, Ivan Antonio Rayas-Alvarez, Juan Karen Reyes, Ana Ctr Invest Opt AC Loma Bosque 115 Guanajuato 37150 Mexico

ISBN: (数字)9781510660687

ISBN: (纸本)9781510660687

Red blood cell (RBC) anomalies are significant symptoms for identification of health disorders and several blood diseases, which involve the modification of the parameters and biophysical characteristics of such cells. An optical system was implemented using a Mirau interferential objective to evaluate the micro-topography of Red Blood Cells in Papanicolaou test (PAP). The phase-shifting algorithm called 8-Bell6 was applied to evaluate the phase map. The phase ambiguity is removed by using three light-emitting diodes (LEDs) emitting at three different wavelengths: 459.7, 512.8 and 637 nm. The micro-topography is evaluated for one of the RBC observed in the sample. Profiles of two perpendicular diameters to each other are showed. The relative error for measurements made with this optical system is 2.9%.

关键词： Mirau objective red blood cells synthetic wavelength phase-shifting algorithm interference microscopy optical metrology

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Development of surface reconstruction algorithms for optical interferometric measurement

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Frontiers of Mechanical Engineering 2021年第1期16卷 1-31页

作者： Dongxu WU Fengzhou FANG Centre of Micro/Nano Manufacturing Technology(MNMT-Dublin) University College DublinDublin 4Ireland School of Control Engineering Northeastern University at QinhuangdaoQinhuangdao 066004China State Key Laboratory of Precision Measuring Technology and Instruments Centre of Micro/Nano Manufacturing Technology(MNMT)Tianjin UniversityTianjin 300072China

Optical interferometry is a powerful tool for measuring and characterizing areal surface topography in precision manufacturing.A variety of instruments based on optical interferometry have been developed to meet the measurement needs in various applications,but the existing techniques are simply not enough to meet the ever-increasing requirements in terms of accuracy,speed,robustness,and dynamic range,especially in on-line or on-machine *** paper provides an in-depth perspective of surface topography reconstruction for optical interferometric ***,configurations,and applications of typical optical interferometers with different capabilities and limitations are *** background and recent advances of fringe analysis algorithms,including coherence peak sensing and phase-shifting algorithm,are *** new developments in measurement accuracy and repeatability,noise resistance,self-calibration ability,and computational efficiency are *** paper also presents the new challenges that optical interferometry techniques are facing in surface topography *** address these challenges,advanced techniques in image stitching,on-machine measurement,intelligent sampling,parallel computing,and deep learning are explored to improve the functional performance of optical interferometry in future manufacturing metrology.

关键词： surface topography measurement optical interferometry coherence envelope phase-shifting algorithm

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End-to-End algorithm for Absolute phase Retrieval 12

End-to-End Algorithm for Absolute Phase Retrieval

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12th International Conference on Information Optics and Photonics (CIOP)

作者： Lu, Jin Li, Yuan Xu, Jian Wang, Fu P. Sun, Xiao G. XIAN Univ Posts & Telecommun Sch Commun & Informat Engn 618 Changan West St Xian 710121 Shaanxi Peoples R China XIAN Univ Posts & Telecommun Res Inst Ind Internet 618 Changan West St Xian 710121 Shaanxi Peoples R China Yangzhou Univ Coll Mech Engn 88 Daxue South Rd Yangzhou 225127 Jiangsu Peoples R China

ISBN: (数字)9781510649903

ISBN: (纸本)9781510649903;9781510649897

Absolute phase plays a very important role for many applications. At present, various techniques have been exhaustively developed for absolute phase recovery. There are three major categories: spatial phase unwrapping, temporal phase unwrapping and deep learning techniques. Analyzing from these methods, a commonality is limited into the procedure of absolute phase recovery. Namely, the conventional algorithms yield to calculate wrapped phase, fringe order and absolute phase in turn. There is a closer dependency between the accuracy of the previous results and the next ones. So more serious errors could accumulate from this computation procedure, meanwhile the recovery speed is decreased. For this reason, we present an end-to-end method to obtain the absolute phase maps by projecting only two-step specially intensity-coded fringe patterns. Unlike the above-mentioned techniques, we can not only compute the wrapped phases from two fringe images, but also decode the corresponding fringe orders simultaneously from two fringe images without any additional patterns. The presented method breaks the limitation and simplifies the procedure of phase unwrapping. Simulations have been carried out to validate the feasibility of the proposed method.

关键词： Digital fringe projection profilometry phase-shifting algorithm phase unwrapping absolute phase recovery

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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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Absolute phase measurement method with few-patterns

Absolute phase measurement method with few-patterns

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Conference on AOPC - Optical Sensing and Imaging Technology

作者： Qi, Xingyang Zhou, Canlin Ding, Yanping Si, Shuchun Li, Hui Shandong Univ Sch Phys Jinan 250100 Peoples R China

ISBN: (纸本)9781510650060;9781510650053

To unwrap the wrapping phase from phase measuring profilometry in 3D surface measurement, many spatial and temporal phase retrieval methods have been presented. However, spatial phase retrieval method often leads to errors because of discontinuous morphology, noise and fringe undersampling. Temporal phase retrieval method can solve this problem. But the method needs multiple frames of fringe images which would take much time. We proposed a novel absolute phase measurement method with few-patterns to overcome this problem. 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 determine the wrapped phase, divide the region, and correct the surface reflectivity of the tested object, a frame of half-period gray-coded pattern is 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. The result shows that our half-period gray-level coding (HGC) method is robust and efficient.

关键词： phase-shifting algorithm phase measuring profilometry absolute phase measurement 3D shape measurement wrapped phase half-period gray-level

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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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Fringe projection decamouflaging

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OPTICS AND LASERS IN ENGINEERING 2020年 134卷 106201-106201页

作者： Deng, Ji Li, Jian Ding, Shumeng Feng, Hao Xiao, Yu Han, Wenzhong Zeng, Zhoumo Tianjin Univ Sch Precis Instrument & Opto Elect 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

Unveiling the cheating mask of camouflage is of great significance in scientific and military research, but the acquisition of detailed information about camouflaged objects remains extremely difficult. This paper presents a fringe projection decamouflaging (FPDC) approach that can provide the position, outer rim profile, and shadow information about well-camouflaged objects in a complex scenario. FPDC requires no expensive instruments, just one camera and one projector for monitoring. A bionic detection field, namely, a phase-jump field, is established to detect the intrusion of camouflaged objects. Based on local variations in this field, multiple-parameter decamouflaging is achieved for the first time. Simulations and experiments show the superiority of this technique, which has potential applications in counterespionage, discovery of wild animals, and search-and-rescue.

关键词： Decamouflaging phase-jump field phase-shifting algorithm

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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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