28 June 2011

A ring-shaped laser no bigger than a pinprick can accurately detect and count individual viruses, the particles that jumpstart cloud formation or those that contaminate the air we breathe. A particle disturbs the light circulating in the ring, splitting the lasing frequency. This split is a measure of the particle's size.

Read more http://www.sciencedaily.com/releases/2011/06/110628113145.htm