Author(s): Na Ji, Daniel E Milkie, Eric Betzig

Abstract:

“Biological specimens are rife with optical inhomogeneities that seriously degrade imaging performance under all but the most ideal conditions. Measuring and then correcting for these inhomogeneities is the province of adaptive optics. Here we introduce an approach to adaptive optics in microscopy wherein the rear pupil of an objective lens is segmented into subregions, and light is directed individually to each subregion to measure, by image shift, the deflection faced by each group of rays as they emerge from the objective and travel through the specimen toward the focus. Applying our method to two-photon microscopy, we could recover near-diffraction–limited performance from a variety of biological and nonbiological samples exhibiting aberrations large or small and smoothly varying or abruptly changing. In particular, results from fixed mouse cortical slices illustrate our ability to improve signal and resolution to depths of 400 μm.”

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Author(s): Xiaodong He, Peng Xu, Jin Wang, and Mingsheng Zhan

Abstract:

“We demonstrated trapping single neutral Rb atoms in micro traps of an optical ring lattice formed by superposing the ±l components of the Laguerre-Gaussian mode, and generated by reflecting a single laser beam from a computer controlled spatial light modulator. A single atom in one trap or two atoms with one each in two traps were identified by observing the fluorescence. The trap array loaded with single atoms was rotated by dynamically displaying the hologram animation movie on the modulator. The modulation period in the fluorescence indicates the rotation of one or two single atoms in the lattice.”

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Author(s): Maximilian Pitzek, Ruth Steiger, Gregor Thalhammer, Stefan Bernet, and Monika Ritsch-Marte

Abstract:

“Holographic optical tweezers typically require microscope objectives with high numerical aperture and thus usually suffer from the disadvantage of a small field of view and a small working distance. We experimentally investigate an optical mirror trap that is created after reflection of two holographically shaped collinear beams on a mirror. This approach combines a large field of view and a large working distance with the possibility to manipulate particles in a large size range, since it allows to use a microscope objective with a numerical aperture as low as 0.2. In this work we demonstrate robust optical three-dimensional trapping in a range of 1mm x 1mm x 2mm with particle sizes ranging from 1.4 μm up to 45 μm. The use of spatial light modulator based holographic methods to create the trapping beams allows to simultaneously trap many beads in complex, dynamic configurations. We present measurements that characterize the mirror traps in terms of trap stiffness, maximum trapping force and capture range.”

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Author(s): Martin Nyvlt, Marek Skeren

Abstract:

“We report a compact holographic optical tweezers based on an LCoS SLM. Optical traps are generated by diffraction of light on the Fresnel-type hologram generated by a fast parallel algorithm that enables real-time 3-D manipulation.”

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