Submicrometer-sized nonspherical particle separation by laser beam

Jaromír Petržala, Miroslav Kocifaj, Ladislav Kómar, and Alexandre Simoneau

The radiation pressure exerted on sub-micrometer-size particles is shown to be an important factor predetermining the impact coordinates of the particles after being illuminated by a laser beam. Unlike spherical particles, the nonspherical ones can be deflected perpendicularly to the beam direction if the momentum transfer from the laser beam to a particle is large enough. Such an optical sorting is a useful technology, which can be used to isolate spherules of a specific size from a population of particles of random sizes and shapes. The system of ideal spheres has a wide range of applications in industry and also in the development of targeted optical devices, and so the methods for fast contact-less particle separation are expected to lead to considerable progress in the field. The theoretical model we have developed is demonstrated in a set of numerical experiments on metallic and nonmetallic particles.

DOI