Why create a camera capable of taking 100 billion frames a second?
Why, to create a light-based version of a sonic boom, of course. LiveScience explains:
The fact that light can travel faster in one material than in another helped scientists to generate photonic Mach cones. First, study lead author Jinyang Liang, an optical engineer at Washington University in St. Louis, 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, the researchers fired pulses of green laser light — each lasting only 7 picoseconds (trillionths of a second) — down the 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.
There’s a movie of the event at LiveScience. For those who don’t want to count the zeros in a trillionth, a picosecond would be 1×10-13 of a second. And while it’s cool what they’ve done, the practical facet of this achievement may actually rest with the laboratory equipment.
The researchers said their new technique could prove useful in recording ultrafast events in complex biomedical contexts such as living tissues or flowing blood. “Our camera is fast enough to watch neurons fire and image live traffic in the brain,” Liang told Live Science. “We hope we can use our system to study neural networks to understand how the brain works.”
