Probing the dynamics of an optically trapped particle by phase sensitive back focal plane interferometry

Basudev Roy; Sambit Bikas Pal; Arijit Haldar; Ratnesh Kumar Gupta; Nirmalya Ghosh; Ayan Banerjee

doi:10.1364/oe.20.008317

Optimized back-focal-plane interferometry directly measures forces of optically trapped particles

Optics Express ◽

10.1364/oe.20.012270 ◽

2012 ◽

Vol 20 (11) ◽

pp. 12270 ◽

Cited By ~ 45

Author(s):

Arnau Farré ◽

Ferran Marsà ◽

Mario Montes-Usategui

Keyword(s):

Focal Plane ◽

Trapped Particles ◽

Optically Trapped

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A balanced, phase sensitive back-focal plane interferometry technique to determine dynamics of a trapped bead in optical tweezers

10.1117/12.921360 ◽

2012 ◽

Author(s):

Basudev Roy ◽

Sambit Bikas Pal ◽

Arijit Haldar ◽

Ratnesh Kumar Gupta ◽

Nirmalya Ghosh ◽

...

Keyword(s):

Optical Tweezers ◽

Focal Plane ◽

Phase Sensitive

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Tandem scanning reflected light microscopy: How it works and applications

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100142104 ◽

1986 ◽

Vol 44 ◽

pp. 84-87

Author(s):

Alan Boyde ◽

Milan Hadravský ◽

Mojmír Petran ◽

Timothy F. Watson ◽

Sheila J. Jones ◽

...

Keyword(s):

Light Microscopy ◽

Focal Plane ◽

Central Symmetry ◽

Single Line ◽

Scanning Microscope ◽

Reflected Light ◽

Illuminating Light ◽

Illuminating Beam

The principles of tandem scanning reflected light microscopy and the design of recent instruments are fully described elsewhere and here only briefly. The illuminating light is intercepted by a rotating aperture disc which lies in the intermediate focal plane of a standard LM objective. This device provides an array of separate scanning beams which light up corresponding patches in the plane of focus more intensely than out of focus layers. Reflected light from these patches is imaged on to a matching array of apertures on the opposite side of the same aperture disc and which are scanning in the focal plane of the eyepiece. An arrangement of mirrors converts the central symmetry of the disc into congruency, so that the array of apertures which chop the illuminating beam is identical with the array on the observation side. Thus both illumination and “detection” are scanned in tandem, giving rise to the name Tandem Scanning Microscope (TSM). The apertures are arranged on Archimedean spirals: each opposed pair scans a single line in the image.

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Symmetry breaking in convergent-beam diffraction

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100154378 ◽

1989 ◽

Vol 47 ◽

pp. 480-481

Author(s):

D.J. Eaglesham

Keyword(s):

Symmetry Breaking ◽

Point Group ◽

X Ray Diffraction ◽

Multiple Diffraction ◽

Space Groups ◽

Atomic Displacements ◽

Small Probe ◽

Phase Sensitive ◽

Convergent Beam

Convergent Beam Electron Diffraction is now almost routinely used in the determination of the point- and space-groups of crystalline samples. In addition to its small-probe capability, CBED is also postulated to be more sensitive than X-ray diffraction in determining crystal symmetries. Multiple diffraction is phase-sensitive, so that the distinction between centro- and non-centro-symmetric space groups should be trivial in CBED: in addition, the stronger scattering of electrons may give a general increase in sensitivity to small atomic displacements. However, the sensitivity of CBED symmetry to the crystal point group has rarely been quantified, and CBED is also subject to symmetry-breaking due to local strains and inhomogeneities. The purpose of this paper is to classify the various types of symmetry-breaking, present calculations of the sensitivity, and illustrate symmetry-breaking by surface strains.CBED symmetry determinations usually proceed by determining the diffraction group along various zone axes, and hence finding the point group. The diffraction group can be found using either the intensity distribution in the discs

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Imaging sub-micron objects with light microscopy: Visualization of the T-4 bacteriophage

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100156158 ◽

1989 ◽

Vol 47 ◽

pp. 834-835

Author(s):

Malcolm Brown ◽

Reynolds M. Delgado ◽

Michael J. Fink

Keyword(s):

Electron Microscopy ◽

Light Microscopy ◽

Focal Plane ◽

Phase Contrast ◽

Dark Field ◽

E Coli ◽

Polystyrene Beads ◽

Television Camera ◽

Transmission Electron ◽

Universal Microscope

While light microscopy has been used to image sub-micron objects, numerous problems with diffraction-limitations often preclude extraction of useful information. Using conventional dark-field and phase contrast light microscopy coupled with image processing, we have studied the following objects: (a) polystyrene beads (88nm, 264nm, and 557mn); (b) frustules of the diatom, Pleurosigma angulatum, and the T-4 bacteriophage attached to its host, E. coli or free in the medium. Equivalent images of the same areas of polystyrene beads and T-4 bacteriophages were produced using transmission electron microscopy.For light microscopy, we used a Zeiss universal microscope. For phase contrast observations a 100X Neofluar objective (N.A.=1.3) was applied. With dark-field, a 100X planachromat objective (N.A.=1.25) in combination with an ultra-condenser (N.A.=1.25) was employed. An intermediate magnifier (Optivar) was available to conveniently give magnification settings of 1.25, 1.6, and 2.0. The image was projected onto the back focal plane of a film or television camera with a Carl Zeiss Jena 18X Compens ocular.

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Microspectroscopy Using a Solid Immersion Lens

Microscopy and Microanalysis ◽

10.1017/s1431927600026817 ◽

2001 ◽

Vol 7 (S2) ◽

pp. 148-149

Author(s):

C.D. Poweleit ◽

J Menéndez

Keyword(s):

Spatial Resolution ◽

Focal Plane ◽

Numerical Aperture ◽

Normal Incidence ◽

Spot Size ◽

Index Of Refraction ◽

Objective Lens ◽

Improvement Factor ◽

Oil Immersion ◽

Long Time

Oil immersion lenses have been used in optical microscopy for a long time. The light’s wavelength is decreased by the oil’s index of refraction n and this reduces the minimum spot size. Additionally, the oil medium allows a larger collection angle, thereby increasing the numerical aperture. The SIL is based on the same principle, but offers more flexibility because the higher index material is solid. in particular, SILs can be deployed in cryogenic environments. Using a hemispherical glass the spatial resolution is improved by a factor n with respect to the resolution obtained with the microscope’s objective lens alone. The improvement factor is equal to n2 for truncated spheres.As shown in Fig. 1, the hemisphere SIL is in contact with the sample and does not affect the position of the focal plane. The focused rays from the objective strike the lens at normal incidence, so that no refraction takes place.

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