Automated High-Dynamic-Range Three-Dimensional Optical Metrology Technique

2014 ◽  
Author(s):  
Laura Ekstrand ◽  
Song Zhang
Keyword(s):  
Exposure Time ◽  
Measurement System ◽  
High Speed ◽  
Manufacturing Industry ◽  
Dynamic Range ◽  
Three Dimensional ◽  
Optical Metrology ◽  
High Contrast ◽  
Accuracy Measurement ◽  
3D Surfaces

Measuring three-dimensional (3D) surfaces with extremely high contrast (e.g., partially shiny surfaces) is extremely difficult with optical metrology methods. Conventional techniques, which involve measurement from multiple angles or camera aperture adjustments, pose issues for high accuracy measurement in the manufacturing industry because they are difficult to automate and often induce undesirable vibrations in the calibrated measurement system. This paper presents a framework for optically capturing high-contrast 3D surfaces via flexible exposure time variation. This technique leverages the binary defocusing technique that was recently developed at Iowa State University to allow digital fringe projection with a camera exposure time far shorter than the projector’s projection period. Since the camera exposure time can be rapidly adjusted in software, the proposed technique could be automated without mechanical adjustments to the measurement system. Moreover, the exposure times are sufficiently short as to be efficiently packed into a projection period, giving this technique the potential for high speed applications. Experimental results will be presented to demonstrate the success of the proposed method.

Servo Design for a 3-D Laser-Tracking Measurement System

1996 ◽  
Vol 118 (3) ◽  
pp. 476-481 ◽  
Author(s):  
Jia-Yush Yen ◽  
Chao-Si Jeng ◽  
Kuang-Chau Fan
Keyword(s):  
Measurement System ◽  
High Speed ◽  
Optimization Technique ◽  
Three Dimensional ◽  
Laser Beams ◽  
Measurement Point ◽  
Position Measurement ◽  
Laser Tracking ◽  
Accuracy Measurement ◽  
Highly Nonlinear

This paper addresses the servo design for a real-time, laser-tracking, three-dimensional (3-D), position measurement system. The 3-D measurement system uses two sets of tracking mirrors to shine laser beams toward the measurement point. By examining the angles of these mirrors, one can calculate the position of this point. The servo loop in the measurement system corrects the mirror orientations by continuously checking and compensating the offset between the out going laser beam and the beam reflected from a retro-reflector attached to the measurement point. To achieve high speed and high accuracy measurement, the tracking servo system has to compensate for the highly nonlinear nature of the system and maintain the laser beams close to the measurement point. This paper derives the relationship between the tracking angle rotations and the measured beam offsets. By including this relationship in the system model, the linear H∞ optimization technique can be applied for controller synthesis. All the design specifications are then directly implemented.

Quantification of Facial Motion for Objective Evaluation Using a High-Speed Three-Dimensional Face Measurement System-A Pilot Study

2006 ◽  
Vol 27 (7) ◽  
pp. 1023-1029 ◽  
Author(s):  
Seiichi Nakata ◽  
Yukio Sato ◽  
Pujitha Gunaratne ◽  
Yoshiro Suzuki ◽  
Saiko Sugiura ◽  
...  
Keyword(s):  
Pilot Study ◽  
Measurement System ◽  
High Speed ◽  
Three Dimensional ◽  
Objective Evaluation ◽  
Facial Motion ◽  
System A ◽  
Dimensional Face

Applications of High-Precise Three-Dimensional Measurement System

2011 ◽  
Vol 222 ◽  
pp. 62-65 ◽  
Author(s):  
Takeshi Hashimoto ◽  
Mitsuo Kaneko ◽  
András Rövid ◽  
Hiroaki Ohta ◽  
Akira Fukuda ◽  
...  
Keyword(s):  
Global Warming ◽  
Measurement System ◽  
Measurement Accuracy ◽  
Three Dimensional ◽  
Long Distance ◽  
Accuracy Measurement ◽  
Close Relationship ◽  
Three Dimensional Measurement ◽  
High Accuracy Measurement ◽  
Moving Speed

To reveal the influence of global warming on glaciers, highly accurate observations of glacier movement must continue every year. It is thought that there is a close relationship between glacier moving speed and global warming. Thus, there have been precise, detailed observations of the movement of the Perito Moreno glacier in Patagonia of the Argentine Republic over the past five years. The measurement method of using GPS and an optical measuring instrument is generally used to monitor glacier movement, but the measurement accuracy attained is not optimal because of the huge size of the glacier. The measurement system used for the Perito Moreno observations, however, could realize high accuracy measurement over long distance. The measurement system is based on the principle of stereo measurement using cameras. This paper describes the results of the Perito Moreno glacier observations of this year and considers the effectiveness of glacier observation using cameras.

scholarly journals Measurement of energy spectrum by using 100 eyes Tomographic PIV

2021 ◽  
Vol 1 (1) ◽  
Author(s):  
Yuki Harada ◽  
Kazuto Saiga ◽  
Jun Sakakibara
Keyword(s):  
Energy Spectrum ◽  
Flow Field ◽  
High Speed ◽  
Dynamic Range ◽  
Three Dimensional ◽  
Turbulent Pipe Flow ◽  
Wave Number ◽  
Reference Curve ◽  
Tomographic Piv ◽  
Particle Images

PIV is one of the methods to measure velocity in a flow field, but its dynamic velocity range is narrower than other flow velocimeter. This disadvantage is particularly apparent in measurements of spectrum in turbulent boundary layers, where the higher wave number side of the spectrum cannot be measured with high accuracy. In this study, we captured images of the same particle in the flow field from many different direction simultaneously, and reduced the measurement error of the particle displacement by averaging the acquired particle positions, so called ‘Multiple Eye PIV’ [Maekawa, A., Sakakibara, J., 2018, Meas. Sci. Tech., 29, 064011]. We applied this method to obtain the energy spectrum in a turbulent pipe flow aiming for resolving higher wave number. Particle images were captured by a single high-speed CMOS camera (Fastcam Nova S6, 6000 fps, Photron) through a mirror array consists of 110 flat mirrors arranged in the shape of an axisymmetric ellipsoid (Fig.1), as shown in Fig.2. The images were evaluated by Tomographic PIV method to resolve three-dimensional velocity field. Fig.3 shows energy spectrum in a pipe measured by Tomographic-PIV with number of mirrors, N, up to 100 in addition to the 2D2C-PIV with a single mirror. Although the spectrum curve for the result of Tomographic-PIV begins to depart from the reference curve at wavenumber beyond 10-1 , such wavenumber grows as N increases, and consequently the plateau of the curve appeared at lower energy. Such a downward shift of the plateau is expected due to the improvement of the dynamic velocityrange, which is approximately one order in energy, i.e. three times in velocity, found between N=4 and 100. Note that the cases of N=4 and 40 loses the dynamic range against the 2C2D-PIV case. From the above, we can summarize that the advantage of Multiple Eye PIV over the 2C2D-PIV is effective when the number of mirrors is more than 40. In this experiment, the issue is that particles images flickered. In order to resolve this issue, we tried to use fluorescent particles, and obtained a clear particle images in the following experiment. We are now analyzing whether the energy spectrum can be measured with higher accuracy due to improved resolution of the particles.

Error Analysis of the ATOS 3D Optical Scanner in Vehicle Measurement

2013 ◽  
Vol 365-366 ◽  
pp. 654-657
Author(s):  
Xue Dong Xie ◽  
Wei Ling Zhao
Keyword(s):  
Measurement System ◽  
Reference Point ◽  
High Speed ◽  
Three Dimensional ◽  
High Accuracy ◽  
Actual Measurement ◽  
Optical Scanning ◽  
Optical Scanner ◽  
Actual Use ◽  
Multiple Scan

ATOS three-dimensional optical scanner is one of the most advanced technologically three-dimensional optical scanning devices. It can automatically put together the multiple scan view image by the reference point of the measurement system, with high accuracy, high speed Etc. It is widely used in automobiles. The paper combines with the experience in vehicle measurements, analysis the error cause in the actual use, points out ways to reduce or eliminate error. It has the great application value to actual measurement.

Method of Detection for Complex Surfaces Based on Industrial Close-Range Photogrammetry

2013 ◽  
Vol 787 ◽  
pp. 944-946
Author(s):  
Li Zhong Wang ◽  
Dong Dong Zhang ◽  
Jin Liang ◽  
Xiao Bo Liao
Keyword(s):  
Measurement System ◽  
Rapid Detection ◽  
Manufacturing Industry ◽  
Detection Method ◽  
Optical Measurement ◽  
Three Dimensional ◽  
Complex Surface ◽  
Close Range Photogrammetry ◽  
Close Range ◽  
Measurement Principle

The rapid detection of the large complex surface was researched with the development of China's manufacturing industry. A industrial close-range photogrammetry new detection Method was put forward based on the analysis of three-dimensional optical measurement principle. The experiment results verify that the accuracy of the three-dimensional optical measurement system independently developed by Xi'an Jiao Tong University meets the Engineering requirements. The main characteristics of large workpiece can be clearly measured and the detection method can be easily used at the production site.

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