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Visualizing colloidal aggregation with femtosecond optical tweezers
Author(s): Debabrata Goswami
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Paper Abstract

Optical tweezers manipulate microscopic objects using forces arising from the subtle interplay of optical scattering and gradient forces of highly focused laser beams. Unlike conventional backscatter signal for optical tweezers, the twophoton fluorescence (TPF) trapping signal from femtosecond optical tweezers (FOTs) shows a slow counterintuitive decay, when the trapped particles are not entirely within the laser-illuminated volume. A change in the corner frequency of FOT is also noted with the TPF technique. These observations are evident even at low average powers. The high peak powers trap not only single microspheres but also encourage optically directed self-assembly. We use TPF signatures of trapped particles to show the existence of a directed self-assembly process and elucidate the structural dynamics during the process of cluster formation.

Paper Details

Date Published: 9 September 2019
PDF: 7 pages
Proc. SPIE 11083, Optical Trapping and Optical Micromanipulation XVI, 110832C (9 September 2019); doi: 10.1117/12.2528518
Show Author Affiliations
Debabrata Goswami, Indian Institute of Technology Kanpur (India)


Published in SPIE Proceedings Vol. 11083:
Optical Trapping and Optical Micromanipulation XVI
Kishan Dholakia; Gabriel C. Spalding, Editor(s)

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