Many experimental techniques in fluid dynamics use lasers. One such technique, particle image velocimetry (PIV), introduces tiny particles into the flow and uses a laser to illuminate the particles. By taking pictures in rapid succession and comparing them, researchers can measure the velocity in different parts of the flow. This technique is incredibly powerful but it’s rarely used to study topics like animal flight, except using mechanical substitutes for live animals.
Part of the reason researchers don’t typically use live animals in this type of experiment is that these very powerful lasers can blind people or animals that aren’t properly protected. So to protect their test subject, Stanford researchers designed and built a special pair of laser safety goggles for their parrotlet. This let the bird fly safely despite the lasers and enabled the researchers to measure flow around realistic bird flight conditions. (Image credit: Stanford News, source, and E. Gutierrez; research credit: E. Gutierrez et al.; submitted by Simon H. via Wired)