A simple single camera 3C3D velocity measurement technique without errors due to depth of correlation and spatial averaging for microfluidics

Cierpka, Christian; Segura, Rodrigo; Hain, Rainer; Kähler, Christian J.

doi:10.1088/0957-0233/21/4/045401

Cited by 124 publications

(118 citation statements)

References 30 publications

(47 reference statements)

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“…The 4-pixel size for the out-of-plane particles at the edge of the measurement volume, i.e. for z 0 = 7.0 mm, is in accordance to both the simplified thin lens equation suggested by Cierpka et al (2010) and the approximate expression for the blur circle as discussed in Scarano (2013).…”

Section: Tomographic Piv Configurationsupporting

confidence: 77%

Dynamic pitching effect on a laminar separation bubble

et al. 2015

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Section: Tomographic Piv Configurationsupporting

confidence: 77%

Dynamic pitching effect on a laminar separation bubble

et al. 2015

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“…Nobach et al (2005) investigated different subpixel interpolation schemes for the detection of the particle center and concluded that most higher order schemes and especially a Gaussian interpolation give reliable results when the particle image diameter is larger than 2.5 pixels. For the investigation here, a wavelet-based algorithm was used (Cierpka et al 2010), since this algorithm works much faster than a Gaussian fit and gives reliable results in a wide range of particle image sizes. Even if the intensity distribution of the particle images does not resembles a Gaussian nicely, adequate detection algorithms can be found and the rms error of the detection of the center is the only limitation for the spatial resolution for PTV.…”

Section: Particle Tracking Velocimetry: Resolution Limitmentioning

confidence: 99%

On the resolution limit of digital particle image velocimetry

2012

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This work analyzes the spatial resolution that can be achieved by digital particle image velocimetry (DPIV) as a function of the tracer particles and the imaging and recording system. As the in-plane resolution for window-correlation evaluation is related by the interrogation window size, it was assumed in the past that single-pixel ensemble-correlation increases the spatial resolution up to the pixel limit. However, it is shown that the determining factor limiting the resolution of single-pixel ensemblecorrelation are the size of the particle images, which is dependent on the size of the particles, the magnification, the f-number of the imaging system, and the optical aberrations. Furthermore, since the minimum detectable particle image size is determined by the pixel size of the camera sensor in DPIV, this quantity is also considered in this analysis. It is shown that the optimal magnification that results in the best possible spatial resolution can be estimated from the particle size, the lens properties, and the pixel size of the camera. Thus, the information provided in this paper allows for the optimization of the camera and objective lens choices as well as the working distance for a given setup. Furthermore, the possibility of increasing the spatial resolution by means of particle tracking velocimetry (PTV) is discussed in detail. It is shown that this technique allows to increase the spatial resolution to the subpixel limit for averaged flow fields. In addition, PTV evaluation methods do not show bias errors that are typical for correlation-based approaches. Therefore, this technique is best suited for the estimation of velocity profiles.

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“…6). Cierpka et al (2010) investigated the laminar flow in a channel with a square cross section of 500 9 500 lm 2 at Re = 23. The cylindrical lens used had a focal length of f cyl = 150 mm.…”

Section: Imaging Based On Aberrations (Astigmatism)mentioning

confidence: 99%

Particle imaging techniques for volumetric three-component (3D3C) velocity measurements in microfluidics

Cierpka

Kähler

2011

J Vis

125

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The reliable measurement of the 3D3C velocity field in microfluidic devices becomes more and more important for future optimization and developments for lab-on-a-chip applications or point-of-care medical diagnosis systems. In the past years, different particle-based imaging methods, such as confocal scanning microscopy, holography, stereoscopic and tomographic imaging or approaches based on defocused particle images or optical aberrations have been developed and applied successfully to measure velocity fields in microfluidic systems. The benefits and drawbacks of these methods will be discussed in detail as the proper understanding of the measurement principle is essential to select the most appropriate technique for a desired measurement application. Once an imaging method is chosen, the velocity can be estimated by correlation-based methods or tracking approaches. The advantages and disadvantages of both methods and the importance of image preprocessing will also be discussed in detail.

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A simple single camera 3C3D velocity measurement technique without errors due to depth of correlation and spatial averaging for microfluidics

Cited by 124 publications

References 30 publications

Dynamic pitching effect on a laminar separation bubble

Dynamic pitching effect on a laminar separation bubble

On the resolution limit of digital particle image velocimetry

Particle imaging techniques for volumetric three-component (3D3C) velocity measurements in microfluidics

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