Among the devices Ramesh Raskar has invented is a four-flash camera that enables the kind of sketching familiar to most from the 1985 music video for the hit pop song “Take on Me” by the Norwegian band A-Ha. Currently he is working on a camera that can see around corners: “It bounces ultrashort bursts of laser light off a rigid surface—the wall opposite an open door, for instance—at several different angles and measures the time it takes the light to return to the camera.” In order for the camera to measure the flight time of light particles, it must take a trillion exposures a second.