Thursday, December 15, 2011

Camera with trillion frames per second captures light

A new camera that records a stunning trillion frames per second is able to show the trajectory of individual photons, the particles of light. The result is that we can see how a small pulse of light hits an object and consequently scatters. Not only is it an awesome piece of technology, it can in the future be used to improve medical imaging, or create more spectacular lighting effects. A video has been made to show off the capabilities of the camera.

Because light moves at an unparalleled 300,000 kilometres per second, one needs a camera that can take an incredible amount of snapshots per second before light can be made visible. If the number of frames per second (FPS) is too low, light will already have passed the camera before a snapshot has been taken. The trillion FPS camera takes snapshots much faster than ordinary cameras. Normal videos are shown at about 25FPS. Some cameras have the capability to shoot video in much higher FPS, such as 300 FPS. If you then play these videos at a 25 FPS rate, you will witness something called slow motion, which is nowadays commonly used in films. Some professional cameras will allow you to shoot video up to 10,000 FPS, but a trillion FPS is definitely way out of that league.

Visualizing photons
Light is something we see all around us. However, the physical phenomenon is actually quite spectacular. Light consists of individual photons, that may be seen as particles, but also behave like waves. We already knew this, but capturing photons on camera has proven to be impossible because of their incredibly high speed. The trillion FPS camera, that has been made by researchers from MIT, allows us to visualize individual photons. It also shows what happens to a beam of light that hits an object, and consequently scatters the photons.

No ordinary camera
To create a camera that shoots with a trillion FPS, the scientists certainly did not use ordinary equipment. A large titanium laser with 500 sensors and several mirrors captures various images that are reconstructed into one picture. Thereafter, the images that were created are stitched together to form a video we can see at a 25 FPS, or similar, rate.

According to the scientists, we can use these high-speed cameras for medical imaging. It is possible to construct an image from light scattering after hitting an object. Currently, we often need to resort to other forms of radiation, such as X-rays. These can be harmful to the body when given in a high dose, or over a long period of time. Additionally, consumers may be able to use the technology in the future, though I am not sure how such a device could really become useful.

Creating photons
In a somewhat related experiment, scientists made use of a magnetic field that vibrates at about 25 percent of the speed of light. With this, they showed that vacuum consists of virtual particles, which can be knocked into existence by giving them energy from the magnetic field. This stunning result was already predicted from quantum theory, but was not yet proven. It goes to show that light may seem an ordinary phenomenon to our eyes, but at the quantum level is incredibly intriguing and exciting.

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