Particle trapped with light and heat

Published in Physics World, 16 Jul 2012

Physicists in Germany have developed a trap for micron-sized particles that relies on both laser light and heat. The “optothermal” trap, which is built around a photonic crystal fibre, puts a new twist on microparticle trapping. The technique could offer a way to make precise measurements of the thermal forces acting on tiny particles and could even be used to sort and concentrate microparticles.

For more than 20¬†years it has been possible to trap microscopically small objects using light. The key development came in 1986 when Arthur Ashkin, Steven Chu and others at Bell Labs in the US invented what became known as optical tweezers: focused laser light that can hold microparticles in mid-space. The phenomenon works because dielectric particles are attracted to the region of strongest electric field, which is where the laser beam is focused. […]

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