Volumetric particle image velocimetry with a single plenoptic camera

Fahringer, Timothy W.; Lynch, Kyle P.; Thurow, Brian S.

doi:10.1088/0957-0233/26/11/115201

Cited by 146 publications

(117 citation statements)

References 34 publications

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“…A plenoptic camera uses an array of microlenses placed in front of a high-resolution image sensor to capture both the spatial and angular information of the light rays. This light-field image can be used to computationally refocus at any desired plane after the data have been recorded as illustrated in figure 2 (for more details on this methodology, refer [35]). The aims of this study are twofold: (i) introduce and validate plenoptic PIV as an alternative novel solution to measure unsteady three-dimensional flow fields in biological flow applications and (ii) apply this technique to quantify the three-dimensional flow field within the native sinus and neo-sinus using plenoptic PIV in two different THV models-the SAPIEN XT and a transparent THV model.…”

Section: Introductionmentioning

confidence: 99%

Three-dimensional extent of flow stagnation in transcatheter heart valves

Raghav

Clifford

Midha

et al. 2019

J. R. Soc. Interface.

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The recent unexpected discovery of thrombosis in transcatheter heart valves (THVs) has led to increased concerns of long-term valve durability. Based on the clinical evidence combined with Virchow's triad, the primary hypothesis is that low-velocity blood flow around the valve could be a primary cause for thrombosis. However, due to limited optical access in such unsteady three-dimensional biomedical flows, measurements are challenging. In this study, for the first time, we employ a novel single camera volumetric velocimetry technique to investigate unsteady three-dimensional cardiovascular flows. Validation of the novel volumetric velocimetry technique with standard planar particle image velocimetry (PIV) technique demonstrated the feasibility of adopting this new technique to investigate biomedical flows. This technique was used to quantify the three-dimensional velocity field in the vicinity of a validated, custom developed, transparent THV in a bench-top pulsatile flow loop. Large volumetric regions of flow stagnation were observed in the neo-sinus throughout the cardiac cycle, with stagnation defined as a velocity magnitude lower than 0.05 m s −1 . The volumetric scalar viscous shear stress quantified via the three-dimensional shear stress tensor was within the range of low shear-inducing thrombosis observed in the literature. Such high-fidelity volumetric quantitative data and novel imaging techniques used to obtain it will enable fundamental investigation of heart valve thrombosis in addition to providing a reliable and robust database for validation of computational tools.

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Section: Introductionmentioning

confidence: 99%

Three-dimensional extent of flow stagnation in transcatheter heart valves

Raghav

Clifford

Midha

et al. 2019

J. R. Soc. Interface.

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“…Its peculiarity is the ability to record both position and propagation direction of light in a single exposure. PI is currently employed in the most diverse applications, from stereoscopy [1][2][3], to microscopy [4][5][6][7], particle image velocimetry [8], particle tracking and sizing [9], wavefront sensing [10][11][12][13] and photography, where it currently enables digital cameras with refocusing capabilities [14,15]. The capability of PI to simultaneously acquire multiple-perspective 2D images brings it among the fastest and most promising methods for 3D imaging with the available technologies [16].…”

mentioning

confidence: 99%

Diffraction-Limited Plenoptic Imaging with Correlated Light

et al. 2017

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Traditional optical imaging faces an unavoidable trade-off between resolution and depth of field (DOF). To increase resolution, high numerical apertures (NA) are needed, but the associated large angular uncertainty results in a limited range of depths that can be put in sharp focus. Plenoptic imaging was introduced a few years ago to remedy this trade off. To this aim, plenoptic imaging reconstructs the path of light rays from the lens to the sensor. However, the improvement offered by standard plenoptic imaging is practical and not fundamental: the increased DOF leads to a proportional reduction of the resolution well above the diffraction limit imposed by the lens NA. In this paper, we demonstrate that correlation measurements enable pushing plenoptic imaging to its fundamental limits of both resolution and DOF. Namely, we demonstrate to maintain the imaging resolution at the diffraction limit while increasing the depth of field by a factor of 7. Our results represent the theoretical and experimental basis for the effective development of the promising applications of plenoptic imaging.Plenoptic imaging (PI) is a novel optical method for recording visual information [1]. Its peculiarity is the ability to record both position and propagation direction of light in a single exposure. PI is currently employed in the most diverse applications, from stereoscopy [1][2][3], to microscopy [4][5][6][7], particle image velocimetry [8], particle tracking and sizing [9], wavefront sensing [10][11][12][13] and photography, where it currently enables digital cameras with refocusing capabilities [14,15]. The capability of PI to simultaneously acquire multiple-perspective 2D images brings it among the fastest and most promising methods for 3D imaging with the available technologies [16]. Indeed, high-speed and large-scale 3D functional imaging of neuronal activity has been demonstrated [7]. Furthermore, first studies for surgical robotics [17], endoscopic application [18] and blood-flow visualization [19] have been performed.The key component of standard plenoptic cameras is a microlens array inserted in the native image plane, that reproduces repeated images of the main camera lens on the sensor behind it [1,15]. This enables reconstruction of light paths, employed, in post-processing, for refocusing different planes, changing point of view and extending depth of field (DOF) within the acquired image. However, a fundamental trade-off between spatial and angular resolution is naturally built in standard plenoptic imaging. If N tot is the total number of pixels per line on the sensor, N x the number of microlenses per line, and N u the number of pixels per line associated with each microlens, then N x N u = N tot . Essentially, standard PI gives the same resolution and DOF one would obtain with a N u times smaller NA. The final advantage is thus practical rather than fundamental, and is limited * francesco.pepe@ba.infn.it † milena.dangelo@uniba.it to higher luminosity (hence SNR) of the final image and parallel acquisition of m...

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“…The method is able to be coupled with particle image velocimetry (PIV). By using a light field camera and several laser triangulations, the flow can be visualized in all three spatial directions .…”

Section: Trendsmentioning

confidence: 99%

Particle Measurement Techniques in Fluid Process Engineering

Lichti

Bart

2018

ChemBioEng Reviews

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Droplets, bubbles, or solid particle concentrations and their particle size distributions markedly influence the process conditions. In this article, an overview with respect to popular invasive and non‐invasive local measurement techniques for bubbles and droplets will be given. It starts with capillary suction probes, laser Doppler anemometry and finally covers actual developments in tomography and optical endoscopic measurement techniques. Furthermore, the possibilities and limitations of analyzing particle size distributions with these different methods in various application fields will be discussed.

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Volumetric particle image velocimetry with a single plenoptic camera

Cited by 146 publications

References 34 publications

Three-dimensional extent of flow stagnation in transcatheter heart valves

Three-dimensional extent of flow stagnation in transcatheter heart valves

Diffraction-Limited Plenoptic Imaging with Correlated Light

Particle Measurement Techniques in Fluid Process Engineering

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