Scientists have spent years creating ever-smaller lasers. Berkeley Lab's latest invention, however, is something special -- and could lead to a significant change in medicine. An international team at the school has developed "microlasers" that are smaller than a red blood cell. The researchers discovered that 5 micron-wide polymer beads mixed with exotic nanoparticles (sodium yttrium fluoride infused with thulium) could reliably emit bright light on specific wavelengths when exposed to infrared light. The concoction makes light bounce around the inner surface of the bead, creating collisions that can repeatedly amplify the light -- it's similar to the "whispering gallery" effect that lets you hear a quiet sound across a giant space with the right acoustics.