EPJ E Highlight - Optical manipulation of particles of all shapes and sizes

Ellipsoidal particle levitating at the optical beam waist, with its long axis aligned to the beam axis. © B. M. Mihiretie et al.

A new study of how particles may respond to the mechanical effects of light helps improve optical manipulation and remote sensing of non-spherical particles.

Manipulation of small objects by light has gained in popularity in the past few years. Now, scientists have performed the first systematic analysis of the behaviour of ellipsoidal particles manipulated by laser beams. The work shows that such particles are constantly moving in and out of the reach of an optical beam, creating oscillations. These findings by a team of researchers from the University of Bordeaux, France, have just been published in EPJ E. This work could help understand the unusual behaviour of rod-like particles manipulated by optical tweezers. Ultimately, the theoretical part of this work could contribute numerical models of how complicated shapes and large sizes scatter laser light. Numerous applications exist in fluid engineering and remote sensing methods.

Focusing a laser beam onto a small particle, in the order of a few micrometres in size, makes the particle move. The effect is a direct consequence of light scattering. Thus, complex algorithms used for light-scattering computations may be tested by measuring the forces induced by the effect of the light beam on the particle—referred to as radiation pressure (RP).

The authors built an experimental set up capable of observing oscillating particles from different directions and measuring their characteristics. At the same time, they also developed a model of the light-particle interaction. They were thus able to calculate the radiation pressure force, induced by the laser beam, and the torque acting on the particle. Balancing such forces with hydrodynamic drag from the fluid around the particle yielded equations for the particle motion. Once solved, the equations gave computed solutions, which nicely reproduced the observed oscillations and could even predict responses that had not previously been observed.

Optically driven oscillations of ellipsoid particles. Part I: Experimental observations. B. M. Mihiretie, P.Snabre, J.C. Loudet, and B. Pouligny (2014), Eur. Phys. J. E 37: 124, DOI 10.1140/epje/i2014-14124-0

Optically driven oscillations of ellipsoidal particles. Part II: Ray-Optics calculations. J.C. Loudet, B. M. Mihiretie, B. Pouligny (2014), Eur. Phys. J. E 37: 125, DOI 10.1140/epje/i2014-14125-y

This was our first experience of publishing with EPJ Web of Conferences. We contacted the publisher in the middle of September, just one month prior to the Conference, but everything went through smoothly. We have had published MNPS Proceedings with different publishers in the past, and would like to tell that the EPJ Web of Conferences team was probably the best, very quick, helpful and interactive. Typically, we were getting responses from EPJ Web of Conferences team within less than an hour and have had help at every production stage.
We are very thankful to Solange Guenot, Web of Conferences Publishing Editor, and Isabelle Houlbert, Web of Conferences Production Editor, for their support. These ladies are top-level professionals, who made a great contribution to the success of this issue. We are fully satisfied with the publication of the Conference Proceedings and are looking forward to further cooperation. The publication was very fast, easy and of high quality. My colleagues and I strongly recommend EPJ Web of Conferences to anyone, who is interested in quick high-quality publication of conference proceedings.

On behalf of the Organizing and Program Committees and Editorial Team of MNPS-2019, Dr. Alexey B. Nadykto, Moscow State Technological University “STANKIN”, Moscow, Russia. EPJ Web of Conferences vol. 224 (2019)

ISSN: 2100-014X (Electronic Edition)

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