Particle Spectroscopy (IMAGE) Optica Caption Multiple species of micron-sized particles are simultaneously illuminated by an infrared laser and a green laser beam. Absorption of the infrared laser light by the particles increases their temperatures, causing them to expand and slightly altering their optical properties. These changes are unique to the material composition of each particle and can be measured by examining the modulation of scattered green light from each particle. Credit Ryan Sullenberger, MIT Lincoln Laboratory Usage Restrictions None License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.