Research group figures out a way to film a laser in normal air bouncing off mirrors (w/ Video)

January 29, 2015 by Bob Yirka report
Light-in-flight measurement and data cube. (a) A laser pulse is reflecting off multiple mirrors, passing three times across the field of view of the SPAD camera (35 × 35 cm2). The same laser is used to create a trigger sent to the camera. The SPAD camera collects scattered photons from the laser pulse. The field of view does not contain the mirrors because the scattered light coming from the mirror surfaces is much more intense than the Rayleigh-scattered light during propagation. (b) The histogram indicates the time of arrival of the laser pulse as measured by pixel (22, 21). The time frames, shown at 0, 1, 2, 3 and 4 ns, show the evolution of the pulse in time as it propagates across the scene. The integration of all frames gives the total path followed by the light, similarly to what can be acquired by an EMCCD camera at maximum gain for an exposure time of 7 s. Credit: Nature Communications 6, Article number: 6021 doi:10.1038/ncomms7021

(Phys.org)—A team of researchers working at the Institute of Photonics and Quantum Sciences, Heriot-Watt University, in Scotland has developed a method for filming a laser beam as it bounces back and forth between mirrors—in normal air. In their paper published in the journal Nature Communications, the team describes how they did it and share the video they created.

Laser beams, by their very nature, travel in a from one point to the next, thus they are nearly impossible to see when traveling through normal air. The path of a single beam can be seen very easily, on the other hand if it happens to pass through smoke, or fog—this is because some of the light in the beam runs into particles that cause some photons to veer from their path and strike a viewers eyes. In this new effort, the researchers wanted to see a beam in normal air, which meant having to use special camera equipment.

Normal air has some particles in it, dust, etc.—photons that bounce from such particles can make it to a viewer's eyes, but they are so few and far between that they cannot be seen. To overcome that problem, the team used a single-photon avalanche diode (SPAD) detector with a very high temporal resolution. It takes a picture of a single photon (using a 32x32 pixel grid) and notes its location. The team pointed the SPAD at a as it was bounced off mirrors in a box, over and over (ten million times) during a ten minute period. That allowed for capturing all of the collisions and deflections that occurred during that time span. A computer then knitted all the photon hits together and animated the results, giving a video that very clearly shows the as it is emitted and then bounces off each of the in the box. The result is both eerie and very cool to watch.

The video will load shortly
Light propagation in air. Credit: Nature Communications 6, Article number: 6021 doi:10.1038/ncomms7021

Though it is not clear just yet if the technique will have any real applications (such as watching plasma develop as ions are heated), the team appears satisfied with their work noting that they were able to achieve their goal.

The video will load shortly
Formation and evolution of laser-induced plasma. Credit: Nature Communications 6, Article number: 6021 doi:10.1038/ncomms7021

Explore further: Researchers build reversible tractor beam that moves objects 100 times farther than other efforts

More information: Single-photon sensitive light-in-fight imaging, Nature Communications, 6, Article number: 6021 DOI: 10.1038/ncomms7021

Abstract
The ability to record images with extreme temporal resolution enables a diverse range of applications, such as fluorescence lifetime imaging, time-of-flight depth imaging and characterization of ultrafast processes. Recently, ultrafast imaging schemes have emerged, which require either long acquisition times or raster scanning and have a requirement for sufficient signal that can only be achieved when light is reflected off an object or diffused by a strongly scattering medium. Here we present a demonstration of the potential of single-photon detector arrays for visualization and rapid characterization of events evolving on picosecond time scales. The single-photon sensitivity, temporal resolution and full-field imaging capability enables the observation of light-in-flight in air, as well as the measurement of laser-induced plasma formation and dynamics in its natural environment. The extreme sensitivity and short acquisition times pave the way for real-time imaging of ultrafast processes or visualization and tracking of objects hidden from view.

Related Stories

Creative Cameras exhibit explores light-in-flight imaging

July 6, 2014

The Creative Cameras exhibition team from Heriot-Watt University and the University of Glasgow are asking some interesting questions. How do you take images so fast that you can see light travelling through air? How do you ...

Physicists find a new way to slow the speed of light

January 23, 2015

(Phys.org)—A team of physicists working at the University of Glasgow has found a way to slow the speed of light that does not involve running it through a medium such as glass or water. Instead, as they explain in their ...

Researchers design plasmonic cavity-free nanolaser

September 22, 2014

(Phys.org) —A team of researchers at Imperial College in London has designed a new type of laser, one that could be made much smaller than today's models because it would be cavity-free. In their paper published in the ...

Recommended for you

Researchers improve qubit lifetime for quantum computers

December 8, 2016

An international team of scientists has succeeded in making further improvements to the lifetime of superconducting quantum circuits. An important prerequisite for the realization of high-performance quantum computers is ...

A nano-roundabout for light

December 8, 2016

Just like in normal road traffic, crossings are indispensable in optical signal processing. In order to avoid collisions, a clear traffic rule is required. A new method has now been developed at TU Wien to provide such a ...

Electron highway inside crystal

December 8, 2016

Physicists of the University of Würzburg have made an astonishing discovery in a specific type of topological insulators. The effect is due to the structure of the materials used. The researchers have now published their ...

1 comment

Adjust slider to filter visible comments by rank

Display comments: newest first

rufusgwarren
not rated yet Jan 30, 2015
Wish there were multiple axis synched shots, with at least 3 different distances away (=) in order to understand the signal spread. The multi-axis with delta d sounds like fun to reconstruct ...

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.