@inproceedings{ed874bd5a39040d88ff80859863bc0a2,

title = "Beam tapering effect in microsphere chains: From geometrical to physical optics",

abstract = "By using polystyrene microspheres with index n=1.59 as a model system we study light focusing and transport properties of chains formed by spheres with diameters varying from 2 to 30 μm. We used techniques of imaging based on light scattering perpendicular to the axis of the chain to visualize and study periodically focused beams in such structures. The results demonstrate good agreement with geometrical optics modeling for sufficiently large spheres, D≫10λ, where D is the sphere diameter and λ is the wavelength of light. For mesoscale structures with 4<D/λ<10 we observed two effects which cannot be explained by geometrical optics. One is a {"}beam tapering{"} effect which is stronger in normalized units than it is theoretically possible in the limit of geometrical optics in short chains. Another effect is reduced power attenuation in sufficiently long chains which is found to be smaller than it is possible in the limit of geometrical optics. Both effects are ascribed to the increased role of physical optics properties. We can also suggest some role of the microjoints developing between polystyrene microspheres in self-assembled structures. The results are important for developing applications requiring focusing of multimodal beams such as mid-infrared laser surgery.",

keywords = "focusing, geometrical optics design, laser surgery, medical optics, microlens, microoptics, microspheres, ophthalmic optics and devices, optical microprobes",

author = "Allen, {Kenneth W.} and Arash Darafsheh and Astratov, {Vasily N.}",

year = "2012",

doi = "10.1117/12.909467",

language = "English",

isbn = "9780819488794",

series = "Progress in Biomedical Optics and Imaging - Proceedings of SPIE",

booktitle = "Laser Resonators, Microresonators, and Beam Control XIV",

note = "Laser Resonators, Microresonators, and Beam Control XIV ; Conference date: 22-01-2012 Through 25-01-2012",

}