Imagine a needle in the center of this device, like the one in compass. Then picture it on the wing of a plane going up on its first test flight. This is a photodiode, and it could record every movement of the needle as the wind spun it around in different directions. Testers on the ground could view the data in real time, then make decisions about how to refine the wing before the next flight. Isorg, a French company, plans to start churning these out at full volume next year.