Profile measurement taken with liquid-crystal gratings

Kakunai, Satoshi; Sakamoto, Tohru; Iwata, Koichi

doi:10.1364/ao.38.002824

Cited by 71 publications

(33 citation statements)

References 7 publications

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“…Because the commercial DLP projector is typically a nonlinear device, the nonlinearity could introduce periodic phase error in the conventional fringe patterns if it is not handled properly. Numerous approaches have been proposed to either actively [15,16] or passively [17][18][19][20] correct the errors caused by nonlinear gamma. In this research, we used a technique introduced in [16] to actively deform the projected fringe patterns.…”

Section: B Phase Error Determinationmentioning

confidence: 99%

Phase error compensation for three-dimensional shape measurement with projector defocusing

et al. 2011

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This paper analyzes the phase error for a three-dimensional (3D) shape measurement system that utilizes our recently proposed projector defocusing technique. This technique generates seemingly sinusoidal structured patterns by defocusing binary structured patterns and then uses these patterns to perform 3D shape measurement by fringe analysis. However, significant errors may still exist if an object is within a certain depth range, where the defocused fringe patterns retain binary structure. In this research, we experimentally studied a large depth range of defocused fringe patterns, from near-binary to near-sinusoidal, and analyzed the associated phase errors. We established a mathematical phase error function in terms of the wrapped phase and the depth z. Finally, we calibrated and used the mathematical function to compensate for the phase error at arbitrary depth ranges within the calibration volume. Experimental results will be presented to demonstrate the success of this proposed technique. Disciplines Computer-Aided Engineering and Design | Mechanical Engineering CommentsThis article is from Applied Optics 50 (2011) This paper analyzes the phase error for a three-dimensional (3D) shape measurement system that utilizes our recently proposed projector defocusing technique. This technique generates seemingly sinusoidal structured patterns by defocusing binary structured patterns and then uses these patterns to perform 3D shape measurement by fringe analysis. However, significant errors may still exist if an object is within a certain depth range, where the defocused fringe patterns retain binary structure. In this research, we experimentally studied a large depth range of defocused fringe patterns, from near-binary to near-sinusoidal, and analyzed the associated phase errors. We established a mathematical phase error function in terms of the wrapped phase and the depth z. Finally, we calibrated and used the mathematical function to compensate for the phase error at arbitrary depth ranges within the calibration volume. Experimental results will be presented to demonstrate the success of this proposed technique.

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Section: B Phase Error Determinationmentioning

confidence: 99%

Phase error compensation for three-dimensional shape measurement with projector defocusing

et al. 2011

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“…Unlike a structured light system using a binary coding method, the DFP system requires calibrating for the nonlinearity of the projection and compensating for the errors associated with it. Even though nonlinearity correction is relatively mature with many methods developed, [19][20][21][22][23][24] our research found that the nonlinearity of the projector actually changes over time; this complicates the problem since a regular nonlinearity calibration is usually sufficient. 5 Nevertheless, good quality phase can be obtained after applying a proper nonlinear gamma correction algorithm.…”

Section: Projector Nonlinear Gamma Correctionmentioning

confidence: 91%

Toward superfast three-dimensional optical metrology with digital micromirror device platforms

Bell

Zhang

2014

Opt. Eng

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Decade-long research efforts toward superfast three-dimensional (3-D) shape measurement leveraging the digital micromirror device (DMD) platforms are summarized. Specifically, we will present the following technologies: (1) high-resolution real-time 3-D shape measurement technology that achieves 30 Hz simultaneous 3-D shape acquisition, reconstruction, and display with more than 300,000 points per frame; (2) superfast 3-D optical metrology technology that achieves 3-D measurement at a rate of tens of kilohertz utilizing the binary defocusing method we invented; and (3) the improvement of the binary defocusing technology for superfast and high-accuracy 3-D optical metrology using the DMD platforms. Both principles and experimental results are presented. Abstract. Decade-long research efforts toward superfast three-dimensional (3-D) shape measurement leveraging the digital micromirror device (DMD) platforms are summarized. Specifically, we will present the following technologies: (1) high-resolution real-time 3-D shape measurement technology that achieves 30 Hz simultaneous 3-D shape acquisition, reconstruction, and display with more than 300,000 points per frame; (2) superfast 3-D optical metrology technology that achieves 3-D measurement at a rate of tens of kilohertz utilizing the binary defocusing method we invented; and (3) the improvement of the binary defocusing technology for superfast and high-accuracy 3-D optical metrology using the DMD platforms. Both principles and experimental results are presented.

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“…Overall, these methods can be classified into two categories: actively modifying the fringe patterns before their projection, 10 or passively compensating the phase error after the fringe patterns are captured. [11][12][13][14][15][16][17][18][19][20][21][22][23] The majority research focused on estimating the gamma coefficients of the projector through different algorithms from the captured fringe patterns, and some by directly calibrating the gamma of the projector. Both active and passive methods have been proved successful in substantially reducing the nonlinearity error caused by the projector.…”

Section: Introductionmentioning

confidence: 99%

Active versus passive projector nonlinear gamma compensation method for high-quality fringe pattern generation

Zhang

2014

SPIE Proceedings

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This paper presents our comparing study on active and passive methods for compensating the phase error induced by the projector nonlinear gamma effect. The active method modifies the fringe patterns before their projection; and the passive method, in contrast, compensates for the phase error after capturing fringe patterns. Our study finds that the active method tends to provides more consistent high-quality fringe patterns regardless the amount of projector's defocusing; yet the effectiveness of the passive method is sensitive to the measurement conditions, albeit the passive method could provide equally good quality phase under the optimal calibration condition. Experimental results will be presented to compare these two different methods. KeywordsNonlinear gamma, phase error, structured light, phase shifting, projector defocusing Copyright 2014 Society of Photo-Optical Instrumentation Engineers. One print or electronic copy may be made for personal use only. Systematic electronic or print reproduction and distribution, duplication of any material in this paper for a fee or for commercial purposes, or modification of the content of the paper are prohibited. ABSTRACTThis paper presents our comparing study on active and passive methods for compensating the phase error induced by the projector nonlinear gamma effect. The active method modifies the fringe patterns before their projection; and the passive method, in contrast, compensates for the phase error after capturing fringe patterns. Our study finds that the active method tends to provides more consistent high-quality fringe patterns regardless the amount of projector's defocusing; yet the effectiveness of the passive method is sensitive to the measurement conditions, albeit the passive method could provide equally good quality phase under the optimal calibration condition. Experimental results will be presented to compare these two different methods.

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Profile measurement taken with liquid-crystal gratings

Cited by 71 publications

References 7 publications

Phase error compensation for three-dimensional shape measurement with projector defocusing

Phase error compensation for three-dimensional shape measurement with projector defocusing

Toward superfast three-dimensional optical metrology with digital micromirror device platforms

Active versus passive projector nonlinear gamma compensation method for high-quality fringe pattern generation

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