Digital Holographic PIV for 3D Flow Measurement

2002 ◽  
Author(s):  
Gang Pan ◽  
Hui Meng
Keyword(s):  
Flow Measurement ◽  
Digital Camera ◽  
Speckle Noise ◽  
3D Measurement ◽  
Depth Of Focus ◽  
3D Flow ◽  
Particle Field ◽  
Benchmark Experiment ◽  
Tracer Particles ◽  
Novel Complex

We have developed a simple digital holographic PIV system for 3D measurement of turbulent and multiphase flow. This system records in-line holograms of tracer particles directly on a digital camera and reconstructs the 3D particle field numerically. Using a novel complex amplitude-based method, we are able to overcome the depth of focus problem and the speckle noise problem associated with the low resolution of digital sensors and the in-line holographic setup. In this paper we will give detailed description of our system, and present the preliminary result of the benchmark experiment using a water jet.

scholarly journals 109 3D flow measurement by means of digital holographic velocimetry(2)

2006 ◽  
Vol 2006 (0) ◽  
pp. _109-1_-_109-4_
Author(s):  
Shinya TAKAOKA ◽  
Takahiro YAMAGUCHI ◽  
Shigeru MURATA
Keyword(s):  
Flow Measurement ◽  
3D Flow

scholarly journals Development of a modular, high-speed plenoptic-camera for 3D flow-measurement

2019 ◽  
Vol 27 (9) ◽  
pp. 13400 ◽  
Author(s):  
Zu Puayen Tan ◽  
Kyle Johnson ◽  
Chris Clifford ◽  
Brian S. Thurow
Keyword(s):  
Flow Measurement ◽  
High Speed ◽  
3D Flow ◽  
Plenoptic Camera

Method to Quantify Flow Reduction in Aneurysmal Cavities of Lateral Wall Aneurysms Produced by Stent Implants Used for Flow Diversion

1995 ◽  
Vol 8 (6) ◽  
pp. 197-200
Author(s):  
N. Fujimura ◽  
M. Ohta ◽  
G. Abdo ◽  
H. Ylmaz ◽  
K.-O Lovblad ◽  
...  
Keyword(s):  
Flow Measurement ◽  
Video Recording ◽  
Digital Camera ◽  
Cerebral Aneurysms ◽  
Lateral Wall ◽  
Post Processing ◽  
Processing Methods ◽  
Flow Reduction ◽  
Comparative Examination ◽  
Quantitative Flow

Stent implants placed across the neck of cerebral aneurysms are capable of reducing aneurysmal flow when coils are not used for filling the aneurysms. It is important to evaluate the effects of flow reduction caused by stent implants used for the treatment of cerebral aneurysms. Subtracted vortex centers path line method (SVC method) is one of the image post processing methods employed for quantitative flow measurement. We developed a modified SVC method by employing Cinematic Angiography (25 frames/s) and digital video recording (30 frames/s) with a commercial digital camera. We successfully compared the flow effectiveness using a tubular silicon model with a sidewall aneurysm. The result suggests that our modified SVC method is useful for a comparative examination of the effect of aneurysmal flow reduction caused by stent implants.

An Investigation of Droplet Diffusion in Isotropic Turbulence With Digital Holographic PIV

Volume 3 ◽  
2004 ◽  
Author(s):  
Edwin Malkiel ◽  
Jian Sheng ◽  
David Garber ◽  
Joseph Katz
Keyword(s):  
Time Series ◽  
Isotropic Turbulence ◽  
Diffusion Rate ◽  
Density Ratio ◽  
Digital Camera ◽  
Stokes Number ◽  
Sample Volume ◽  
Tracer Particles ◽  
Fluid Velocities ◽  
Digital Holograms

In-line digital holography is utilized to measure the Lagrangian trajectory of droplets in locally isotropic turbulence. The objective of these measurements is to determine the diffusion rate of these droplets as a function of density ratio between the continuous and dispersed phases, Stokes number and turbulence level relative to the quiescent settling/rise velocity of the droplets. The present experiments are conducted using diesel fuel with diameters of 0.5–2 mm, specific gravity of 0.85 and Stokes number in the 0.2 to 5 range. The droplets are injected into a 50 × 50 × 50 mm sample volume located in the center of a 160 1 tank. The turbulence is generated by four spinning grids, located symmetrically in the corners of the tank. Planar PIV has been used to characterize the turbulence prior to the experiments. A time series of in-line digital holograms is recorded at 2000 frames per second using a 1000×1000 pixel digital camera by back illuminating the sample volume with a collimated laser beam. Numerical reconstruction generates a time series of high-resolution images of the droplets and tracer particles throughout the sample volume. Subsequent analysis is used to obtain the velocity along the droplet trajectory. Lagrangian correlations can then be used for calculating the diffusion rate of these droplets. In a smaller sample volume, with a 15×15 mm cross section, and by using localized seeding, we can also simultaneously measure the droplet velocity along with the velocity of the fluid in the vicinity of this droplet. The results provide statistics on the correlations between the droplet and fluid velocities.

Multi-perspective measurement of yarn hairiness using mirrored images

2016 ◽  
Vol 88 (6) ◽  
pp. 621-629 ◽  
Author(s):  
Lei Wang ◽  
Bugao Xu ◽  
Weidong Gao
Keyword(s):  
3D Model ◽  
Three Dimensional ◽  
Digital Camera ◽  
3D Measurement ◽  
Multiple Perspectives ◽  
Multiple Images ◽  
Image Processing Techniques ◽  
Yarn Hairiness ◽  
Processing Techniques ◽  
Planar Mirrors

Most photoelectric and imaging methods for yarn hairiness measurements often provide underestimated data of hairy fibers measured from light projection, which ignores the spatial orientations and shapes of protruding fibers. In this project, a three-dimensional (3D) system was developed to detect hairy fibers from multiple perspectives and to reconstruct a 3D model for the yarn that permits fibers to be traced spatially. The system utilized two angled planar mirrors to view a yarn from five different perspectives simultaneously, and a digital camera to capture the multiple images in one panoramic picture. The image-processing techniques were used to dissect the panoramic picture into five sub-images containing separate views of the yarn, and to segment the sub-images to obtain yarn silhouettes showing the edges of the yarn and hairy fibers. A 3D model of the yarn could be built by merging the five silhouettes with the angles defined by the scene geometry of the dual mirrors. From the 3D model, hairy fibers protruding from the yarn core could be traced in the space for accurate length measurements. The system represents a simple and practical solution for the 3D measurement of yarn hairiness.

3D Modeling of Submarine Based on Digital Close Range Photogrammetry

2012 ◽  
Vol 256-259 ◽  
pp. 2324-2327
Author(s):  
Ying Jun Sun ◽  
Xin Guo Cui ◽  
Zun Yi Xu
Keyword(s):  
Control System ◽  
Active Control ◽  
Production Efficiency ◽  
Digital Camera ◽  
3D Measurement ◽  
Intersection Angle ◽  
Large Intersection ◽  
Close Range ◽  
Active Control System ◽  
Angle Of View

A new method to realize 3D measurement and modeling based on Active Control System was put forward in the paper. The Active Control System included two parts: one was for the calibration of digital camera, and the other was for the six-freedom control of digital camera. This method enlarged the intersection angle and improves the intersection precision by multi-baseline photography; enlarges the angle of view by panning photography, and resolves the difficulty of matching for images with large intersection angle. The experiments proved that this method can acquire the high accuracy and improves the production efficiency.

scholarly journals 1109 3D flow measurement by means of DHPIV with a gradient-based method

2005 ◽  
Vol 2005.80 (0) ◽  
pp. _11-17_-_11-18_
Author(s):  
Takahiro YAMAGUCHI ◽  
Shigeru MURATA ◽  
Takafumi MORIHARA
Keyword(s):  
Flow Measurement ◽  
3D Flow ◽  
Gradient Based

scholarly journals Multiple Laser Stripe Scanning Profilometry Based on Microelectromechanical Systems Scanning Mirror Projection

Micromachines ◽  
2019 ◽  
Vol 10 (1) ◽  
pp. 57 ◽  
Author(s):  
Gailing Hu ◽  
Xiang Zhou ◽  
Guanliang Zhang ◽  
Chunwei Zhang ◽  
Dong Li ◽  
...  
Keyword(s):  
Microelectromechanical Systems ◽  
Speckle Noise ◽  
Measurement Technology ◽  
3D Measurement ◽  
High Quality ◽  
Full Field ◽  
Scanning Mirror ◽  
Laser Stripe ◽  
Measurement Efficiency ◽  
Mechanical Movement

In traditional laser-based 3D measurement technology, the width of the laser stripe is uncontrollable and uneven. In addition, speckle noise in the image and the noise caused by mechanical movement may reduce the accuracy of the scanning results. This work proposes a new multiple laser stripe scanning profilometry (MLSSP) based on microelectromechanical systems (MEMS) scanning mirror which can project high quality movable laser stripe. It can implement full-field scanning in a short time and does not need to move the measured object or camera. Compared with the traditional laser stripe, the brightness, width and position of the new multiple laser stripes projected by MEMS scanning mirror can be controlled by programming. In addition, the new laser strip can generate high-quality images and the noise caused by mechanical movement is completely eliminated. The experimental results show that the speckle noise is less and the light intensity distribution is more even. Furthermore, the number of pictures needed to be captured is significantly reduced to 1 / N ( N is the number of multiple laser stripes projected by MEMS scanning mirror) and the measurement efficiency is increased by N times, improving the efficiency and accuracy of 3D measurement.

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