ID 137

Optical Force Applied to Aerosol Particles for Diagnostics

 

Abstract:

A one meter length symmetric confocal cavity was pumped with a continuous laser. Aerosol particles that were, on average, 2 m/s velocity and 14 um droplet size, were sent through the cavity waist at an oblique angle. A high speed camera was configured to view the particle-laser cross-point at an orthogonal an orthogonal angle relative to the particle flow. When expanding or contracting the cavity length, a consistently linear particle acceleration or deceleration was observed, whereas particle acceleration or deceleration was not observed for a standing wave configuration. Particle tracking software was then used to measure particle velocity. By applying Newton’s law, the measured particle acceleration can be converted to optical force, mass, or particle size. These results imply that particles can be sorted by size provided the right conditions. In principle, this technique can be scaled down to measure nano-meter sized particles and low velocity particles which are currently inaccessible by other methods such as Phase Doppler or diffraction.