scholarly journals Step Surface Profile Measurement Based on Fringe Projection Phase-Shifting Using Selective Sampling

Photonics ◽  
2021 ◽  
Vol 8 (12) ◽  
pp. 592
Author(s):  
Songsong Zhang ◽  
Haisong Huang
Keyword(s):  
Measurement Errors ◽  
Surface Profile ◽  
Phase Shifting ◽  
Surface Shape ◽  
Fringe Projection ◽  
Profile Measurement ◽  
Phase Extraction ◽  
Stepped Surfaces ◽  
Selective Sampling ◽  
Extraction Algorithm

Fringe projection is a non-contact optical method that is widely used in the optical precision measurement of complex stepped surfaces. However, the accuracy of the fringe phase extraction employed has a direct impact on the measurement precision of the surface shape. Where phase-shifting measurement is used, the classical equal step phase extraction algorithm can only be used to measure simple and smooth surfaces, and leads to measurement errors on complex stepped surfaces, which affects the accuracy of the phase extraction. In addition, the iterative process lasts for a long time, resulting in a low efficiency. This paper proposes a step-by-step phase-shifting extraction algorithm based on selective sampling to measure the contour of the stepped surface. Firstly, the fringe pattern is sampled at equal intervals to reduce the iterative calculation time. Finally, the accurate measurement phase is calculated by the alternating iteration method. The phase extraction accuracy and iteration times are compared in experimental measurements between classical iterative algorithms such as four-step phase-shifting algorithms and the variable phase shift phase interpolation algorithm based on selective sampling. It is shown that the variable frequency phase-shifting extraction algorithm based on selective sampling has a shorter operation time, smaller error, and higher accuracy than the traditional iterative algorithm in fringe projection measuring complex stepped surfaces.

A New Three-Dimensional Profilometer for Surface Profile Measurement Using Digital Fringe Projection and Phase Shifting

2005 ◽  
Vol 295-296 ◽  
pp. 471-476
Author(s):  
Liang Chia Chen ◽  
S.H. Tsai ◽  
Kuang Chao Fan
Keyword(s):  
High Speed ◽  
Structured Light ◽  
Three Dimensional ◽  
Surface Profile ◽  
Phase Shifting ◽  
Fringe Projection ◽  
Surface Measurement ◽  
Profile Measurement ◽  
Digital Fringe Projection ◽  
Fringe Patterns

The development of a three-dimensional surface profilometer using digital fringe projection technology and phase-shifting principle is presented. Accurate and high-speed three-dimensional profile measurement plays a key role in determining the success of process automation and productivity. By integrating a digital micromirror device (DMD) with the developed system, exclusive advantages in projecting flexible and accurate structured-light patterns onto the object surface to be measured can be obtained. Furthermore, the developed system consists of a specially designed micro-projecting optical unit for generating flexibly optimal structured-light to accommodate requirements in terms of measurement range and resolution. Its wide angle image detection design also improves measurement resolution for detecting deformed fringe patterns. This resolves the problem in capturing effective deformed fringe patterns for phase shifting, especially when a coaxial optical layout of a stereomicroscope is employed. Experimental results verified that the maximum error was within a reasonable range of the measured depth. The developed system and the method can provide a useful and effective tool for 3D full field surface measurement ranging from µm up to cm scale.

scholarly journals Measurement of step surface contour based on variable sampling phase shift interference phase extraction algorithm based on selective sampling

2020 ◽  
Author(s):  
Songsong Zhang ◽  
Haisong Huang ◽  
Qiaoqiao Xiong
Keyword(s):  
Phase Shift ◽  
Iterative Algorithm ◽  
Phase Shifting ◽  
Variable Frequency ◽  
Phase Extraction ◽  
Selective Sampling ◽  
Unknown Phase ◽  
Extraction Algorithm ◽  
Interference Phase ◽  
Frequency Phase

Abstract Variable frequency phase shift interferometry is widely applied in optical precision measurement, with the accuracy of phase extraction’s direct impact on that of phase shift interferometry. In the variable-frequency phase-shift interferometry, the commonly used phase-shifting devices are prone to phase shift errors, because the ordinary equal-step phase extraction algorithm, which can be merely used to measure simple and smooth surface, influences the accuracy of phase extraction resulting in measuring error, and causes inefficiency led by the long time the iterative process lasts for when applied in complex stepped surfaces measurement. As a sort of step-by-step phase-shifting phase extraction algorithm based on selective sampling is used to measure the step surface contour, the interference image is firstly sampled at equal intervals to reduce the iterative calculation, and in view of the fact that the phase calibration of the test system is not required in this algorithm, the measured phase is given by using the alternating iterative method despite the unknown phase and unknown phase shift amount. The phase extraction accuracy and iteration time among traditional iterative algorithm, four-step phase shift algorithm and the variable phase shift phase interpolation algorithm based on selective sampling are compared in the simulation and experiment. It is shown that the variable frequency phase shifting interference phase extraction algorithm based on selective sampling has shorter operation time, less error and higher accuracy than traditional iterative algorithm in measuring complex step surface.

scholarly journals Fringe projection profilometry for recovering 2.5D shape of ancient coins

ACTA IMEKO ◽  
2021 ◽  
Vol 10 (1) ◽  
pp. 142
Author(s):  
Giuseppe Schirripa Spagnolo ◽  
Lorenzo Cozzella ◽  
Fabio Leccese
Keyword(s):  
Cultural Heritage ◽  
Good Accuracy ◽  
Three Dimensional ◽  
Surface Profile ◽  
Fringe Projection ◽  
Profile Measurement ◽  
Dimensional Model ◽  
Three Dimensional Model ◽  
Cultural Heritage Objects ◽  
Physical Access

<p class="Abstract">The relief of form is undoubtedly one of the most topical topics in the field of cultural heritage. Physical access to historic and artistic manufactures can be limited by a lot of factors. For example, the access to the collection of the ancient coins is difficult, especially for students. Indeed, for coins digital archive of high-quality three-dimensional model and remote fruition is of great interest. The use of projected fringes for the measurement of surface profile is a well-developed technique. In this paper, we present a surface profile measurement system for small objects of cultural heritage where it is important not only to detect the shape with good accuracy but also to capture and archive the signs due to ageing. The illustrated equipment is simple, reliable, and cheap. Furthermore, some examples of acquisitions are presented to demonstrate the potentiality of the proposed scheme for recovering 2.5D shape of cultural heritage objects.</p>

A Fast Phase Extraction Algorithm with One-Step π Phase-Shifting

2016 ◽  
Vol 36 (6) ◽  
pp. 0612003
Author(s):  
朱荣刚 Zhu Ronggang ◽  
朱日宏 Zhu Rihong ◽  
何勇 He Yong
Keyword(s):  
Phase Shifting ◽  
Phase Extraction ◽  
Fast Phase ◽  
Extraction Algorithm ◽  
One Step

Microscopic Surface Measurement Using Phase Shifting Method

2015 ◽  
Vol 771 ◽  
pp. 200-203 ◽  
Author(s):  
Suprijanto ◽  
Naila Zahra ◽  
E. Juliastuti
Keyword(s):  
Surface Profile ◽  
Skin Surface ◽  
Phase Shifting ◽  
Phase Image ◽  
Accurate Information ◽  
Profile Measurement ◽  
Imaging Device ◽  
Skin Imaging ◽  
Digital Microscope ◽  
Phase Shifting Method

Accurate information of microscopic topography is very important for efficacy assessment of a surface texture of skin health. Due to the limitations of the direct visual assessment of skin microscopic topography, an optical dermastocopy is very common to be used as skin imaging device to magnify skin topography based on a white light reflection. The limitation of this method is its poor spatial resolution to quantify skin topography. In this work, microscopic skin imaging based on phase shifting method is configured using a DLP pico-projector with LED illumination and a handheld digital microscope. As illuminator for the digital microscope, the DLP projector is programmed to generate patterned light on skin surface. Image processing is required in providing accurate information of surface topography. The first step, a wrapped phase shifting must be extracted from acquired intensity images. The second step is obtaining unwrapped phase image, which is a critical process because it must be recovered from wrapped phase shifting that containednoise. Finally, phase offset due to multiples of 2π during phase unwrapping must be removed. Early experiments on simple object are carried out to test the level of distortion of fringe in several variations of contrast and also to test the performance of the system on several frequency variations. The test results indicate the depth proportion obtained from absolute phase image has the same trend as the proportion of direct measurement. Implementation on the skin surface profile performed on three test areas: the back of the hand and knuckle creases. Based on quantitative and qualitative analysis,our proposed scheme of skin imaging based on phase shifting is promising for surface profile measurement and imaging of the skin.

High-efficiency iterative phase extraction algorithm based on selective sampling

2016 ◽  
Vol 37 (1) ◽  
pp. 64-68
Author(s):  
Zhang Chen-hao ◽  
Wan Xin-jun ◽  
Yang Bo ◽  
Xie Shu-ping ◽  
Yue Lin
Keyword(s):  
High Efficiency ◽  
Phase Extraction ◽  
Selective Sampling ◽  
Extraction Algorithm
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