The Experts below are selected from a list of 327 Experts worldwide ranked by ideXlab platform
Jia Lin - One of the best experts on this subject based on the ideXlab platform.
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Imaging Subresolution Membrane Curvature in Living Cells by Back Focal Plane Positioning Polarized Total Internal Reflection Microscopy (TIRFM)
Biophysical Journal, 2012Co-Authors: Adam D. Hoppe, Jason G. Kerkvliet, Jia LinAbstract:Induction of membrane curvature is an essential step in the formation of endocytic vesicles and viral particles. Axelrod and co-workers have shown that polarized total internal reflection fluorescence microscopy (pol-TIRFM) can be used to visualize membrane curvature in cells labeled with the lipophilic fluorophore DiI. We describe an approach for creating s-pol and p-pol TIRF fields using a commercial microscope system equipped with a 2-D scan head to position polarized laser beams at distinct azimuthal positions in the Back Focal Plane (BFP) of a high numerical aperture TIRF lens. This configuration allows for reduction of interference fringing of the coherent light by alternating illumination at azimuthal positions separated by 180 degrees. Additional reduction of fringing could be obtained by sweeping the laser through small arcs in the BFP of about 8 degrees with minimal impact on the polarization of the TIRF fields. We investigated the performance of this pol-TIRFM approach for visualization of endocytosis and viral budding in cells labeled with DiI and either the endocytic marker clathrin-YFP or viral budding marker HIV Gag-YFP.
Gabriella Cincotti - One of the best experts on this subject based on the ideXlab platform.
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Spectral shifts of a partially coherent field after passing through a lens.
Optics letters, 1997Co-Authors: Claudio Palma, Gabriella CincottiAbstract:A study of the spectral shifts of a well-known type of partially coherent field, namely, one formed by Gaussian Schell model beams, propagating beyond an optical system reveals that there are no shifts in the geometric-image Plane, whereas the greatest (blue) shift occurs in the Back Focal Plane. These results are relevant for spectroradiometric measurements.
Peter J. Reece - One of the best experts on this subject based on the ideXlab platform.
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Using Back Focal Plane interferometry to probe the influence of Zernike aberrations in optical tweezers.
Optics letters, 2017Co-Authors: Thomas F. Dixon, Lachlan W. Russell, Ana Andres-arroyo, Peter J. ReeceAbstract:We experimentally investigate the influence of geometric aberrations in optical tweezers using Back Focal Plane interferometry. We found that the introduction of coma aberrations causes significant modification to the Brownian motion of the trapped particle, producing an apparent cross-coupling between the in-Plane aberrated axis and the weaker propagation axis. This coupling is evidenced by the emergence of a second dominant low frequency Lorentzian feature in the position power spectral density. The effect on Brownian motion was confirmed using a secondary unaberrated probe beam, ruling out the possibility of systematic optical effects related to the detection system.
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Silicon Nanoparticles: Correlating Spectral Properties with Brownian Dynamics
Optics in the Life Sciences Congress, 2017Co-Authors: Sarah Lugay, Ana Andres-arroyo, Peter J. ReeceAbstract:Using a combination of spectroscopic methods and Back Focal Plane interferometry we explore the correlation between scattering properties and translational/rotational Brownian dynamics of trapped asymmetric silicon nanoparticles that exhibit optical resonances.
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Measurement of Hydrodynamic Coupling by Time-shared Optical Tweezers
Optics in the Life Sciences, 2015Co-Authors: Wen Jun Toe, Ana Andres-arroyo, Peter J. ReeceAbstract:We demonstrate a technique for monitoring fast dynamics between multiple optically trapped particles using time-shared optical tweezers and Back Focal Plane interferometry. We examine the viability of this method and show how it can be expanded to more complex systems.
Christoph F. Schmidt - One of the best experts on this subject based on the ideXlab platform.
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Two-Dimensional Tracking of ncd Motility by Back Focal Plane Interferometry
Biophysical Journal, 1998Co-Authors: Miriam W. Allersma, F. Gittes, Michael J. Decastro, Russell J. Stewart, Christoph F. SchmidtAbstract:A technique for detecting the displacement of micron-sized optically trapped probes using far-field interference is introduced, theoretically explained, and used to study the motility of the ncd motor protein. Bead motions in the Focal Plane relative to the optical trap were detected by measuring laser intensity shifts in the Back-Focal Plane of the microscope condenser by projection on a quadrant diode. This detection method is two-dimensional, largely independent of the position of the trap in the field of view and has approximately 10-micros time resolution. The high resolution makes it possible to apply spectral analysis to measure dynamic parameters such as local viscosity and attachment compliance. A simple quantitative theory for Back-Focal-Plane detection was derived that shows that the laser intensity shifts are caused primarily by a far-field interference effect. The theory predicts the detector response to bead displacement, without adjustable parameters, with good accuracy. To demonstrate the potential of the method, the ATP-dependent motility of ncd, a kinesin-related motor protein, was observed with an in vitro bead assay. A fusion protein consisting of truncated ncd (amino acids 195-685) fused with glutathione-S-transferase was adsorbed to silica beads, and the axial and lateral motions of the beads along the microtubule surface were observed with high spatial and temporal resolution. The average axial velocity of the ncd-coated beads was 230 +/- 30 nm/s (average +/- SD). Spectral analysis of bead motion showed the increase in viscous drag near the surface; we also found that any elastic constraints of the moving motors are much smaller than the constraints due to binding in the presence of the nonhydrolyzable nucleotide adenylylimidodiphosphate.
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Interference model for Back-Focal-Plane displacement detection in optical tweezers.
Optics letters, 1998Co-Authors: F. Gittes, Christoph F. SchmidtAbstract:The lateral position of an optically trapped object in a microscope can be monitored with a quadrant photodiode to within nanometers or better by measurement of intensity shifts in the Back Focal Plane of the lens that is collimating the outgoing laser light. This detection is largely independent of the position of the trap in the field of view. We provide a model for the essential mechanism of this type of detection, giving a simple, closed-form analytic solution with simplifying assumptions. We identify intensity shifts as first-order far-field interference between the outgoing laser beam and scattered light from the trapped particle, where the latter is phase advanced owing to the Gouy phase anomaly. This interference also reflects momentum transfer to the particle, giving the spring constant of the trap. Our response formula is compared with the results of experiments.
Frank Cichos - One of the best experts on this subject based on the ideXlab platform.
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Fast measurement of photonic stop bands by Back Focal Plane imaging
Physical Review B, 2013Co-Authors: Rebecca Wagner, Frank CichosAbstract:Back Focal Plane imaging microscopy of the autofluorescence of a colloidal photonic crystal at fixed wavelength is used to visualize photonic stop bands. Emission angles of up to ${74}^{\ensuremath{\circ}}$ against the crystals surface normal are detected. Structure and orientation of the crystal lattice, quality of the ordering, and the influence of defects on the optical properties can be probed at high spatial resolution. Exemplary results reveal domains with four-, six- and threefold symmetry, where the latter dominates, as expected for fcc lattices.
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Back Focal Plane imaging spectroscopy of photonic crystals
Applied Physics Letters, 2012Co-Authors: Rebecca Wagner, Lars Heerklotz, Nikolai Kortenbruck, Frank CichosAbstract:Back Focal Plane imaging spectroscopy is introduced to record angle resolved emission spectra of 3-dimensional colloidal photonic crystals. The auto-fluorescence of the colloids is used to quickly map the photonic band structure up to 72 % of the solid angle of a semisphere with the help of a high numerical aperture objective. Local excitation provides spatially resolved information on the photonic crystal’s optical properties. The obtained fractional density of states allows direct conclusions on the crystal’s stacking faults or defects.
