We demonstrate that surface plasmon polaritons can be generated by optical vortex beams at normal incidence focused on a metal surface. The surface plasmon resonant angle can be modulated by the radius of the optical vortex beam in the case of different metal/dielectric interface configurations. Our experiments show that the fluorescence in the vicinity of the metal film surface can effectively be excited and detected within the inner ring of the optical vortex beams due to the localized surface plasmon polaritons.
A technique for high-resolution wide-field fluorescence microscopy by using standing surface plasmon waves induced by optical vortices (OVs) is proposed, aiming at harnessing its unique dynamic properties to sequentially illuminate specimen with different phase-shifted interference excitation field. Topological charges of the OV are employed to modulate phase-shifting of the interference pattern. Numerical studies and experimental results reveal an achievement of 0.25λ optical resolution, a factor of twofold improvement compared with the standard total-internal-reflection fluorescence microscopy.
Manipulation of surface plasmon polaritons (SPP) by phase modulation of incident light beams is proposed with analytical and numerical verifications when an optical vortex (OV) beam is employed as an example. Fundamental functionalities of a plasmonic chip such as in-plane focusing, coupling and multiplexing of SPP by sequentially varying the topological charge of OV beam are demonstrated. Complementary to the manually-controlled optical-path-different technique reported in literature, the proposed method reveals a direct phase transform from OV beam to SPP with dynamic and reconfigurable advantages.
Correct part orientation has been the key to many successful automation applications, and often vibratory bowls were used. Traditionally, the design and tooling of the vibratory bowlsare limited to a group of skilled experts. In this paper a feature-based framework for the automatic selection and sequencing of orientating devices is presented. A direct link between part representation and the selection and sequencingof modular orientating devices is provided by a spatial technique,in place of traditional CAD representation. Also described is the classification of a part's orientating features and classification of orientating devices. These two classificationsare integrated into a knowledge-based systemthat will automatically generate sequences of modular orientating devices.
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