Abstract by Leslie Howe
Physics and Astronomy
Levitating Microscopic Particles in a Laser Beam via Photophoresis
Photophoresis is the effect of heating objects with light and subsequent interaction with surrounding air molecules, which can produce a force on the object. This effect has been shown to hold small dust particles in the focus of a laser, which can be moved around rapidly to create three-dimensional images in free space. The details of the photophorific force in this application is not well understood. In particular, it remains to explain exactly how the particle remains stably trapped in the laser focus as opposed to fleeing it. I will highlight unanswered questions in this regard and outline experiments intended to answer them. A better understanding of this phenomenon may enable engineering for more stable control and more rapid movement of particles held in a scanning laser focus.