This ultra-fast camera allows you to film the movement and polarization of light in 3D

In everyday life, the events that we photograph concern phenomena generally moving at low speeds or at speeds specific to the macroscopic world. However, in some areas of research, scientists need ultra-fast cameras, recording several hundred thousand, if not millions, of frames per second. Recently, a team of engineers developed a new camera capable of recording up to 100 billion images per second (enough to see light moving) and turning it into a three-dimensional movie. This technology, which also detects polarized light, could help solve some microscopic mechanisms that are still mysterious in physics.

In his quest to develop ever faster cameras, Caltech’s Lihong Wang has developed technology capable of blazing speeds of 70 trillion frames per second (70,000 billion), fast enough to see the movement of light. . But just like your cell phone camera, it can only produce flat images.

However, Wang’s lab recently went further to create a camera that not only records video at blazingly fast speeds, but does so in three dimensions. The device is described in the review Nature Communications. It uses the same underlying technology as Wang’s other Ultra-Fast Compact Image Capture (UPC) devices, and is capable of capturing up to 100 billion images per second.

Diagram of the structure of the ultrafast camera developed by Wang’s team. Credits: Jinyang Liang et al. 2020

An ultra-fast camera with a stereoscopic mechanism

It’s fast enough to take 10 billion photos, more images than the entire human population of the world, in the time it takes you to blink. Wang calls the new technology “single shot stereopolarimetric compressed ultrafast photography” or SP-CUP. In CUP technology, all the frames of a video are captured in a single action without repeating the event. This makes a CUP camera extremely fast (a good cell phone camera can shoot 60 frames per second).

Wang added a third dimension to this lightning-fast imagery. When a person looks at the world around him, he perceives that some objects are closer to him and that some objects are further away. Such depth perception is possible thanks to our two eyes, each of which observes objects and their surroundings from a slightly different angle. The information from these two images is combined by the brain into a single 3D image.

SP-CUP ultra-fast 3D film camera laser reflection surface
3D film of a laser beam passing through a scattering medium and bouncing off reflective surfaces, recorded by the SP-CUP camera. Credit: Caltech

The SP-CUP camera works essentially the same way. ” The camera is now stereoscopic. We have only one lens, but it works as two halves that provide two views with a lag. Two channels imitating our eyes “. Just as our brains do with the signals it receives from our eyes, the computer that runs the SP-CUP camera processes the data from these two channels into a three-dimensional movie.

Detection of polarized light useful in many applications

SP-CUP also exhibits another ability that no human has – the ability to see the polarization of light waves. Light polarization refers to the direction in which light waves oscillate as they travel. Consider a guitar string. If the string is pulled up (for example, by a finger) and then released, the string vibrates vertically. If the finger pinches it from the side, the string vibrates horizontally. Ordinary light has waves that vibrate in all directions.

Polarized light, however, has been altered so that its waves all vibrate in the same direction. This can happen by natural means, for example when light is reflected off a surface, or as a result of artificial manipulation, as happens with polarizing filters.

Although our eyes cannot directly detect the polarization of light, the phenomenon has been exploited in a range of applications: from LCD screens to polarized sunglasses, to camera lenses in optics and devices. that detect hidden stresses in materials and three-dimensional configurations of molecules.

The combination of the high-speed three-dimensional imaging of SP-CUP and the use of polarization information makes it a powerful tool that can be applied to a wide variety of scientific problems. In particular, the team hopes it will help researchers better understand the physics of sonoluminescence, a phenomenon in which sound waves create tiny bubbles in water or other liquids. As the bubbles quickly collapse after forming, they emit a burst of light.

Sources: Nature Communications

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