Ultrafast Camera First Time Captures ‘Sonic Booms’ of Light
You must experienced clap of sound when any speeding jet fly overhead that followed after the jet whizzed by. This sound clap called a sonic boom. This sonic boom generate when any object travel faster than the speed of the sound.
So when an aircraft flying at supersonic speed create a cone-shaped sonic booms, pulses of light can leave behind cone-shaped wakes of light. A super fast camera has captured this phenomena for the first-ever.
Scientists have developed a super-fast camera that captured an elusive pulses of light leaving behind cone shaped waves of light, just like aircraft flying at supersonic speeds create sonic booms. The pressure waves created by the traveling object pile up on each other, creating the thunderclap you hear. For the first time, a group of scientists managed to capture that effect on camera.
When an object moves through air, it propels the air in front of it away, creating pressure waves that move at the speed of sound in all directions. If the object is moving at speeds equal to or greater than sound, it outruns those pressure waves. As a result, the pressure waves from these speeding objects pile up on top of each other to create shock waves known as sonic booms.
What they captured?
Sonic booms are confined to conical regions known as “Mach cones”. We know that the light can travel faster in one material than in another, this phenomena helped scientists to develop photonic Mach cones. Study lead author Jinyang Liang, an optical engineer and his colleagues designed a narrow tunnel filled with dry ice fog. This tunnel was sandwiched between plates made of a mixture of silicone rubber and aluminum oxide powder.
Then, researchers fired a pulses of green laser light. Each pulse fired for only 7 picoseconds (trillionths of a second) in tunnel. These pulses could scatter off the specks of dry ice within the tunnel, generating light waves that could enter the surrounding plates.
The green light that the scientists used traveled faster inside the tunnel than it did in the plates. As such, as a laser pulse moved down the tunnel, it left a cone of slower-moving overlapping light waves behind it within the plates.
How they captured?
To capture this phenomena researcher developed a camera named streak camera. Basically the Streak Camera could capture images at speeds of 100 billion frames per second in a single exposure. This new camera captured three different views of the phenomenon: one that acquired a direct image of the scene, and two that recorded temporal information of the events so that the scientists could reconstruct what happened frame by frame.
With the help of this study they could prove useful in recording ultra fast events in complex biomedical contexts such as living tissues or flowing blood.