Dynamic stereo microscopy for studying particle sedimentation

Lee, M. P.; Gibson, Graham M.; Phillips, David B.; Padgett, Miles J.; Tassieri, Manlio

doi:10.1364/oe.22.004671

Cited by 26 publications

(16 citation statements)

References 22 publications

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“…This results in the four images from different illumination directions positioned adjacently on the camera ( Figure 1c). 7,17,18 There is also a separate single laser beam trap, coupled into the system using a polarising beam splitter, allowing single beads to be trapped in the sample 7 …”

Section: Methodsmentioning

confidence: 99%

“…Therefore, it is possible to separate and retrieve individual images by placing a diffractive optical element in the Fourier plane, such as a Spatial Light Modulator (SLM). 7,8 By using stereo-microscopy in conjunction with optical tweezers it is possible to track the three dimensional trajectories of optically trapped micro beads. Optical tweezers use a high numerical aperture objective lens to tightly focus a laser beam, creating high field gradients that enable 3 dimensional trapping of microscopic particles.…”

Section: Introductionmentioning

confidence: 99%

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Quad stereo-microscopy

et al. 2014

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Stereo-microscopy is a technique that enables a sample to be imaged from two directions simultaneously, allowing the tracking of microscopic objects in three dimensions. This is achieved by illuminating the sample from different directions, each illumination direction producing an individual image. These images are superimposed in the image plane but can be easily separated using a diffractive optical element in the Fourier plane of the imaging arm. Therefore this enables 3-dimensional coordinates to be reconstructed using simple 2-dimensional image tracking and parallax. This is a powerful technique when combined with holographic optical tweezers (HOT), where multiple objects can be trapped and tracked simultaneously in three dimensions. In this work, we extend this concept to four different illumination directions: quad stereo-microscopy. This allows us to measure the accuracy of tracking in three dimensions, and to optimise the system.

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Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Quad stereo-microscopy

et al. 2014

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“…Figures. S1-S7 285 Table S1 References (25)(26)(27)(28)(29)(30)(31)(32)(33)(34)(35)(36)(37)(38)(39)(40)…”

Section: Supplementary Materialsmentioning

confidence: 99%

Microrheology reveals microscale viscosity gradients in planktonic systems

Guadayol

Mendonça

Segura-Noguera

et al. 2020

Preprint

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Microbial activity in planktonic systems creates a dynamic and heterogeneous microscale 15 seascape that harbours a diverse community of microorganisms and ecological interactions of global significance. Over recent decades a great deal of effort has been put into understanding this complex system, particularly focusing on the role of chemical patchiness, while overlooking a governing feature of microbial life affected by biological activity: viscosity. Here we use microrheological techniques to measure viscosity at length scales relevant to microorganisms. 20Our results reveal the viscous nature and the spatial extent of the phycosphere and show heterogeneity in viscosity at the microscale. Such heterogeneity affects the distribution of chemicals and microorganisms, with pervasive and profound implications for the functioning of the entire planktonic ecosystem.One Sentence Summary: Microrheology measurements unveil the existence of viscous layers 25 around phytoplankton cells and aggregates.Main Text:

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“…The SLM separates the images by diffracting the light from each illumination direction to a different position on the camera. The flexibility of an SLM enables the incorporation of stereo-scopic imaging with additional modalities such as dark-field imaging [18] and dynamic refocussing to track particles over an increased depth of field [19]. A stereo-scopic version of digital holography has also recently been demonstrated, improving the axial resolution of holographic images [20].…”

Section: Introductionmentioning

confidence: 99%

“…Figure 1 shows a schematic of the experimental set-up. We use a compact design for stability, based on the microscope described by Lee et al [19], with a modified illuminator which holds four optical fibre light guides each illuminating the sample from a different direction. We use an SLM to diffract each of the four views of the sample to a different location on the camera.…”

Section: Introductionmentioning

confidence: 99%

Four-directional stereo-microscopy for 3D particle tracking with real-time error evaluation

Hay¹,

Gibson²,

Lee³

et al. 2014

Opt. Express

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Abstract:High-speed video stereo-microscopy relies on illumination from two distinct angles to create two views of a sample from different directions. The 3D trajectory of a microscopic object can then be reconstructed using parallax to combine 2D measurements of its position in each image. In this work, we evaluate the accuracy of 3D particle tracking using this technique, by extending the number of views from two to four directions. This allows us to record two independent sets of measurements of the 3D coordinates of tracked objects, and comparison of these enables measurement and minimisation of the tracking error in all dimensions. We demonstrate the method by tracking the motion of an optically trapped micro-sphere of 5 µm in diameter, and find an accuracy of 2-5 nm laterally, and 5-10 nm axially, representing a relative error of less than 2.5% of its range of motion in each dimension. Simpson, "An optically actuated surface scanning probe," Opt. Express 20, 29679-29693 (2012). 12. C. Alpmann, R. Bowman, M. Woerdemann, M. Padgett, and C. Denz, "Mathieu beams as versatile light moulds for 3d micro particle assemblies," Opt. Express 18, 26084-26091 (2010

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Dynamic stereo microscopy for studying particle sedimentation

Cited by 26 publications

References 22 publications

Quad stereo-microscopy

Quad stereo-microscopy

Microrheology reveals microscale viscosity gradients in planktonic systems

Four-directional stereo-microscopy for 3D particle tracking with real-time error evaluation

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