There are things in life that can be reasonably predicted. The tide rises and falls. The moon grows and sets. A billiard ball bounces around a table according to ordered geometry.
And then there are things that challenge easy prediction: the hurricane that changes direction without warning. Spray water in a fountain. The graceful suffering of branches growing from a tree.
These phenomena and others like them can be described as chaotic systems and are remarkable for exhibiting behaviors that are predictable at first but grow more and more random over time.
Because of the great role that chaotic systems play in the world around us, scientists and mathematicians have long sought to understand them better. Now, Caltech̵
In the latest edition of Scientific progress, Wang describes how he used an ultra-fast camera of his own design that recorded video at a billion frames per second to observe the motion of laser light in a chamber specifically designed to evoke chaotic reflections.
“Some cavities are non-chaotic, so the path the light goes is predictable,” Wang says. But in his current work, he and his colleagues have used the ultra-fast camera as a tool to study a chaotic cavity, “where light takes a different path each time we repeat the experiment.”
The camera uses a technology called compressed ultrafast photography (CUP), which Wang has shown in other research to be capable of speeds as fast as 70 trillion images per second. Second. The speed at which a CUP camera takes video enables it to see light – the fastest thing in the universe – as it moves.
But CUP cameras have another feature that makes them uniquely suited for studying chaotic systems. Unlike a traditional camera that shoots one video image at a time, a CUP camera shoots essentially all of its images at once. This allows the camera to capture the entire chaotic path of a laser beam through the chamber at once.
It means something, because in a chaotic system, the behavior is different every time. If the camera captured only part of the action, the behavior that was not recorded could never be investigated because it would never happen in exactly the same way again. It would be like trying to photograph a bird, but with a camera that can only capture one body part at a time; each time the bird landed near you, it would also be a different species. Even if you could try to gather all your photos into a composite bird picture, the cobbled bird would have the beak of a crow, the neck of a stork, the wings of another duck, the tail of a hawk, and the legs of a chicken. Not exactly helpful.
Wang says his CUP camera’s ability to capture the chaotic movement of light can breathe new life into the study of optical chaos, which has applications in physics, communication and cryptography.
“It was a really hot field some time ago, but it’s dead, maybe because we did not have the tools we needed,” he says. “The experimentalists lost interest because they could not perform the experiments, and the theorists lost interest because they could not validate their theories experimentally. This was a fun demonstration to show people in the field that they finally have an experimental tool.”
The paper, which describes the research entitled “Real-time observation and control of optical chaos”, appears in the January 13 issue of Scientific progress.
New ultra-fast camera takes 70 trillion images per second
Linran Fan et al. Real-time observation and control of optical chaos Scientific progress 13 Jan 2021: Vol. 7, No. 3, eabc8448, DOI: 10.1126 / sciadv.abc8448
Provided by the California Institute of Technology
Citation: Study of chaos with one of the world’s fastest cameras (2021, January 13) retrieved January 14, 2021 from https://phys.org/news/2021-01-chaos-world-fastest-cameras.html
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