A phase-triggering technique to extend the phase-measurement range of a photorefractive novelty filter microscope

Krishnamachari, Vishnu Vardhan; Denz, Cornélia

doi:10.1007/s00340-004-1596-1

Cited by 10 publications

(2 citation statements)

References 16 publications

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“…In the filtered image the object exhibits trail formation, which is a characteristic feature of photorefractive novelty filters. 9 While being undesired in some applications, 7,11 it gives an easy access to the velocity of the underlying object.…”

Section: Full-field Particle Velocimetry With a Photorefractive Opticmentioning

confidence: 99%

Full-field particle velocimetry with a photorefractive optical novelty filter

Woerdemann

Holtmann

Denz

2008

Applied Physics Letters

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We utilize the finite time constant of a photorefractive optical novelty filter microscope to access full-field velocity information of fluid flows on microscopic scales. In contrast to conventional methods such as particle image velocimetry and particle tracking velocimetry, not only image acquisition of the tracer particle field but also evaluation of tracer particle velocities is done all-optically by the novelty filter. We investigate the velocity dependent parameters of two-beam coupling based optical novelty filters and demonstrate calibration and application of a photorefractive velocimetry system. Theoretical and practical limits to the range of accessible velocities are discussed.

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Section: Full-field Particle Velocimetry With a Photorefractive Opticmentioning

confidence: 99%

Full-field particle velocimetry with a photorefractive optical novelty filter

Woerdemann

Holtmann

Denz

2008

Applied Physics Letters

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“…As an interferometric technique, DynPCM can be employed to measure phase changes in a range from 0 ≤ φ ≤ π [22]. This unambiguous phase measurement range can be extended up to 2π by a simple phasetriggering technique [23]. Using a two-wavelength setup, phase measurements up to several π have been demonstrated.…”

Section: Dynamic Phase-contrast Microscopymentioning

confidence: 99%

Depth-resolved velocimetry of Hagen–Poiseuille and electro-osmotic flow using dynamic phase-contrast microscopy

et al. 2010

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We quantitatively investigate the axial imaging properties of dynamic phase-contrast microscopy, with a special focus on typical combinations of tracer particles and magnifications that are used for velocimetry analysis. We show, for the first time, that a dynamic phase-contrast microscope, which is the integration of an all-optical novelty filter in a commercially available inverted microscope, can visualize threedimensional velocity fields with a significantly reduced optical sectioning depth. The depth of field for dynamic phase-contrast microscopy is extracted from the three-dimensional response function and compared with the respective values for incoherent bright-field illumination. These results are then used to perform a depth-resolved particle image velocimetry analysis of Hagen-Poiseuille as well as electro-osmotically actuated flows in a microchannel.

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