Systematic bias compensation for a moire fringe projection system

2005 ◽  
Author(s):  
D. Purcell ◽  
A. Samara ◽  
A. Davies ◽  
F. Farahi
Keyword(s):  
Fringe Projection ◽  
Systematic Bias ◽  
Projection System ◽  
Moire Fringe ◽  
Moiré Fringe ◽  
Bias Compensation

Measurement of scapular kinematics with the moiré fringe projection technique

2010 ◽  
Vol 43 (6) ◽  
pp. 1215-1219 ◽  
Author(s):  
Pollyanna F. Gomes ◽  
Meinhard Sesselmann ◽  
Christina D.C.M. Faria ◽  
Priscila A. Araújo ◽  
Luci F. Teixeira-Salmela
Keyword(s):  
Fringe Projection ◽  
Projection Technique ◽  
Scapular Kinematics ◽  
Moire Fringe ◽  
Moiré Fringe

scholarly journals Application of Moiré Fringe Projection Method Development for Teeth Deformation Analysis

2016 ◽  
Author(s):  
Jose Luis Valin Rivera ◽  
Edison Gonçalves ◽  
Paulo Vinícius Soares ◽  
Giovana Milito ◽  
Matsuyoshi Mori ◽  
...  
Keyword(s):  
Projection Method ◽  
Method Development ◽  
Fringe Projection ◽  
Deformation Analysis ◽  
Moire Fringe ◽  
Moiré Fringe

Effective wavelength calibration for moiré fringe projection

2006 ◽  
Vol 45 (34) ◽  
pp. 8629 ◽  
Author(s):  
Daryl Purcell ◽  
Angela Davies ◽  
Faramarz Farahi
Keyword(s):  
Fringe Projection ◽  
Effective Wavelength ◽  
Wavelength Calibration ◽  
Moire Fringe ◽  
Moiré Fringe

Simulation and Contrast Analysis of tem Images of Cracks

1990 ◽  
Vol 48 (1) ◽  
pp. 578-579
Author(s):  
D. Goyal ◽  
A. H. King
Keyword(s):  
Displacement Vector ◽  
Crack Tip ◽  
Perfect Crystal ◽  
Operating Conditions ◽  
Displacement Fields ◽  
Fringe Contrast ◽  
Orthogonal Geometry ◽  
Moire Fringe ◽  
Moiré Fringe

TEM images of cracks have been found to give rise to a moiré fringe type of contrast. It is apparent that the moire fringe contrast is observed because of the presence of a fault in a perfect crystal, and is characteristic of the fault geometry and the diffracting conditions in the TEM. Various studies have reported that the moire fringe contrast observed due to the presence of a crack in an otherwise perfect crystal is distinctive of the mode of crack. This paper describes a technique to study the geometry and mode of the cracks by comparing the images they produce in the TEM because of the effect that their displacement fields have on the diffraction of electrons by the crystal (containing a crack) with the corresponding theoretical images. In order to formulate a means of matching experimental images with theoretical ones, displacement fields of dislocations present (if any) in the vicinity of the crack are not considered, only the effect of the displacement field of the crack is considered.The theoretical images are obtained using a computer program based on the two beam approximation of the dynamical theory of diffraction contrast for an imperfect crystal. The procedures for the determination of the various parameters involved in these computations have been well documented. There are three basic modes of crack. Preliminary studies were carried out considering the simplest form of crack geometries, i. e., mode I, II, III and the mixed modes, with orthogonal crack geometries. It was found that the contrast obtained from each mode is very distinct. The effect of variation of operating conditions such as diffracting vector (), the deviation parameter (ω), the electron beam direction () and the displacement vector were studied. It has been found that any small change in the above parameters can result in a drastic change in the contrast. The most important parameter for the matching of the theoretical and the experimental images was found to be the determination of the geometry of the crack under consideration. In order to be able to simulate the crack image shown in Figure 1, the crack geometry was modified from a orthogonal geometry to one with a crack tip inclined to the original crack front. The variation in the crack tip direction resulted in the variation of the displacement vector also. Figure 1 is a cross-sectional micrograph of a silicon wafer with a chromium film on top, showing a crack in the silicon.

scholarly journals Absolute Phase Retrieval Using One Coded Pattern and Geometric Constraints of Fringe Projection System

2018 ◽  
Vol 8 (12) ◽  
pp. 2673 ◽  
Author(s):  
Xu Yang ◽  
Chunnian Zeng ◽  
Jie Luo ◽  
Yu Lei ◽  
Bo Tao ◽  
...  
Keyword(s):  
Phase Shift ◽  
Phase Retrieval ◽  
Code Word ◽  
Geometric Constraints ◽  
Fringe Projection ◽  
Average Intensity ◽  
Fringe Order ◽  
Projection System ◽  
Absolute Phase ◽  
Three Phase

Fringe projection technologies have been widely used for three-dimensional (3D) shape measurement. One of the critical issues is absolute phase recovery, especially for measuring multiple isolated objects. This paper proposes a method for absolute phase retrieval using only one coded pattern. A total of four patterns including one coded pattern and three phase-shift patterns are projected, captured, and processed. The wrapped phase, as well as average intensity and intensity modulation, are calculated from three phase-shift patterns. A code word encrypted into the coded pattern can be calculated using the average intensity and intensity modulation. Based on geometric constraints of fringe projection system, the minimum fringe order map can be created, upon which the fringe order can be calculated from the code word. Compared with the conventional method, the measurement depth range is significantly improved. Finally, the wrapped phase can be unwrapped for absolute phase map. Since only four patterns are required, the proposed method is suitable for real-time measurement. Simulations and experiments have been conducted, and their results have verified the proposed method.

An automatic high-speed scanner for moiré fringe techniques

1972 ◽  
Vol 7 (2) ◽  
pp. 151-156 ◽  
Author(s):  
D J Hitchings ◽  
A R Luxmoore
Keyword(s):  
High Speed ◽  
Peak Detection ◽  
Optical Signal ◽  
Single Line ◽  
Scanning System ◽  
Moiré Fringes ◽  
Moire Fringe ◽  
Scanning Line ◽  
Moiré Fringe

A high-speed scanning system has been developed to locate the centres of moiré fringes along any single line. The system comprises a rotating-mirror scanner for conversion of an optical signal to electrical; this conversion is followed by peak detection, storage, and print-out electronics. Up to 20 fringes can be scanned in 1 ms. The results are printed in terms of fringe separations along the scanning line.

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