When applying phase-stepping interferometry to measure wavefront with aberration, distortion is caused by various factors and the main one is phase-shifting error from phaseshifter. In this paper, the calculation the...
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ISBN:
(纸本)9780819483850
When applying phase-stepping interferometry to measure wavefront with aberration, distortion is caused by various factors and the main one is phase-shifting error from phaseshifter. In this paper, the calculation theory and consequence in measurement error of the phase shift algorithm are discussed. These algorithms include traditional three-phasealgorithm, traditional four-phasealgorithm, traditional five-phasealgorithm, carre algorithm, new compensating four-phasealgorithm and new compensating five-phasealgorithm. According to the theory analysis and computer stimulation, these methods are compared through introduce phase-shifting error, wavefront aberration and Gauss noise, the results show the new compensating five-phasealgorithm is immune to phase-shifting error, and its result is insensitive to Gauss noise, it can improve measurement accuracy effectively.
Based on the polynomial theory, the error propagation characteristics of the widely used N-step discrete Fourier transform (N-DFT) phase-shiftalgorithm were analyzed via theoretical analysis, under the effect of Gamm...
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Based on the polynomial theory, the error propagation characteristics of the widely used N-step discrete Fourier transform (N-DFT) phase-shiftalgorithm were analyzed via theoretical analysis, under the effect of Gamma distortion and phase detuning. The results showed that the N-DFT algorithm could not simultaneously suppress both types of error. A robust linear phase-shift (RLPS) algorithm was designed, the performance of the RLPS and 8-DFT algorithms in terms of spectral response, detuning robustness, and GS/N\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${G}_{S/N}$$\end{document} was briefly analysis by Manuel Servin method. The Simulation analysis and comparison of the results show that the RLPS algorithm could suppress both types of error simultaneously, which exhibited better stability and accuracy than N-DFT and exponential algorithms, particularly in gradient measurement stability, peak-to-valley (PV) and root-mean-square (RMS) error suppression. Moreover, a physical experiment apparatus was built to test unidirectionally inclined plane mirror and concave mirror using the RLPS, N-DFT, and exponential algorithms. The results showed that the RLPS algorithm could significantly improve the measurement stability and accuracy in the presence of detuning and without screen Gamma calibration.
When applying phase-stepping interferometry to measure wavefront with aberration,distortion is caused by various factors and the main one is phase-shifting error from phase *** this paper,the calculation theory and co...
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When applying phase-stepping interferometry to measure wavefront with aberration,distortion is caused by various factors and the main one is phase-shifting error from phase *** this paper,the calculation theory and consequence in measurement error of the phase shift algorithm are *** algorithms include traditional three-phasealgorithm,traditional four-phasealgorithm,traditional five-phasealgorithm,carre algorithm,new compensating four-phasealgorithm and new compensating five-phase *** to the theory analysis and computer stimulation,these methods are compared through introduce phase-shifting error,wavefront aberration and Gauss noise,the results show the new compensating five-phasealgorithm is immune to phase-shifting error,and its result is insensitive to Gauss noise,it can improve measurement accuracy effectively.
A new fiber-optic current sensor (FOCS) is described which employs phaseshifting algorithms to process the optical signal. In this approach the sensing element consists of a coil low birefringence fiber placed betwee...
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ISBN:
(纸本)9780819469304
A new fiber-optic current sensor (FOCS) is described which employs phaseshifting algorithms to process the optical signal. In this approach the sensing element consists of a coil low birefringence fiber placed between one polarizer and four analyzers. In the polarimeter layout, the output light from the current sensing element is divided into four beams through three nonpolarizing beamsplitters, and in each beam path is placed an analyzer and a detector. This paper discusses the characteristics of the optical current sensors, specifically for relaying applications were measurement of fault current is required. The design of the sensor, results and shiftalgorithms for electrical current characterization will be presented.
A four-frame phaseshift method and an associated algorithm using unequal phase steps are presented. The unique advantage of this method is that it becomes insensitive to phaseshifter nonlinearity because of the perf...
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A four-frame phaseshift method and an associated algorithm using unequal phase steps are presented. The unique advantage of this method is that it becomes insensitive to phaseshifter nonlinearity because of the performance of a special procedure, in which the phaseshifts are shared out between the reference beam and the object beam. By this means, any phaseshifter can work as long as one phaseshift is accurately known. On the basis of the technique, a simple calibration method for the linear phaseshifter is suggested. The influences of phaseshifter miscalibration, detector nonlinearity and random noise on the algorithm are investigated, and the optimal phaseshifts are given.
Time-of-flight (Tof) range imaging is a new suitable choice for measurement and modeling in many different applications such as robotics, machine vision, medical imaging, multimedia and so forth. But due to the techno...
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ISBN:
(纸本)9781479921805
Time-of-flight (Tof) range imaging is a new suitable choice for measurement and modeling in many different applications such as robotics, machine vision, medical imaging, multimedia and so forth. But due to the technology's relatively new appearance on the market the knowledge of its capabilities is very low. This paper presents an uncertainty analysis for optical Tof sensors based on a four-phase-shiftalgorithm for range value calculation. The measurement uncertainty indicates the interval of the values that the quantity to be measured (in this paper range information) may assume, after all systematic biases have been corrected. The uncertainty analysis is evaluated by simulation. At the end of the paper the results are discussed.
A multiparty quantum key distribution protocol is proposed in this paper. The distributor uses a phaseshift operation to encode the key sequence into some EPR sequences. The participants perform a phaseshift operati...
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A multiparty quantum key distribution protocol is proposed in this paper. The distributor uses a phaseshift operation to encode the key sequence into some EPR sequences. The participants perform a phaseshift operation on the particles from Bell states according to their private keys, and t out of n participants can use the Lagrange interpolation to recover the EPR sequences. Furthermore, two cooperating participants, one from each of the two disjoint groups, can always reconstruct the original key sequence by only a single-photon measurement. Performance analysis shows that the proposed protocol is simpler and more efficient than the existing schemes.
During the last years, time-of-flight (TOF) sensors achieved a significant impact onto research fields in machine vision. In comparison to other common 3-D sensing devices, they combine the advantages of active sensor...
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During the last years, time-of-flight (TOF) sensors achieved a significant impact onto research fields in machine vision. In comparison to other common 3-D sensing devices, they combine the advantages of active sensors providing accurate distance measurements and camera-based systems recording a 2-D matrix at a high frame rate. In this paper, a new approach is presented which increases the range calculation time by a factor of four. Experimental results show that the proposed algorithm is well suited for real-time processing of the range images of continuous wave TOF cameras.
Registered depth and intensity data at a high frame rate, a compact design, low weight, and a reduced power consumption have motivated the increasing usage of lock-in time-of-flight (TOF) cameras in research areas suc...
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Registered depth and intensity data at a high frame rate, a compact design, low weight, and a reduced power consumption have motivated the increasing usage of lock-in time-of-flight (TOF) cameras in research areas such as computer graphics, machine vision, and robotics. The state-of-the-art practice is to use continuous wave modulation with square waves for TOF cameras. Square waves can be easily generated digitally with a high accuracy and stability using programmable logic devices. In this paper, a modulation method based on sine waves is proposed, which significantly reduces the depth distortion offset (wiggling effect) of lock-in TOF cameras. Furthermore, a model for the noise distribution in the depth image is derived. This model can predict the performance of the proposed modulation method for each pixel in real time.
Camera calibration is the most essential and usually the first step in computer vision applications. The results highly depend on the accuracy of the feature extraction. Conventional feature extraction methods suffer ...
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Camera calibration is the most essential and usually the first step in computer vision applications. The results highly depend on the accuracy of the feature extraction. Conventional feature extraction methods suffer from perspective and lens distortion. In this paper, a novel feature extraction method is proposed by using fringe patterns groups as calibration target. Each group comprises six sinusoidal, in which, three are used for calculating vertical phases and the other three for horizontal phases. A three-step phase shift algorithm is used for wrapped phase calculation. Then, feature points are detected with a 2D phase-difference pulse detection method and refinement is done by simple interpolation. Finally, camera calibration is done by using these features as control points, experimental results indicated the proposed method accurate and robust. (C) 2013 Elsevier GmbH. All rights reserved.
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