Three objects — a disk, triangle, and square – were used to test the acuity of the imaging technique. The left image reveals the objects as they would appear if directly sampled. The middle image is reconstructed for collected photons and shows a distorted disk and a rounded square. The triangle was rendered most clearly. The image on the right shows the objects as they would be seen from the side. Little spatial information is evident from this perspective.
by the erratic behavior of photons zooming around and bouncing off
objects and walls inside a room, researchers from the Massachusetts
Institute of Technology (MIT), Harvard University, the University of
Wisconsin, and Rice University combined these bouncing photons with
advanced optics to enable them to “see” what’s hidden around the corner.
This technique, described in a paper published today in the Optical
Society’s (OSA) open-access journal Optics Express, may one day prove invaluable in disaster recovery situations, as well as in noninvasive biomedical imaging applications.
photons as particles bouncing right off the walls and down a corridor
and around a corner—the ones that hit an object are reflected back. When
this happens, we can use the data about the time they take to move
around and bounce back to get information about geometry,” explains
Otkrist Gupta, an MIT graduate student and lead author of today’s Optics Express paper.
advanced optics in the form of an ultrafast laser and a 2D streak
camera, both of which operate on the order of trillions of cycles per
second, the team exploited being able to capture billions of images per
second to demonstrate the technology’s ability to “see” objects by
analyzing the light moving around a corner or through water bottle.
cameras differ from other cameras in that the image it forms is
determined by the time profile of the incoming photons. “This type of
imaging provides us with a very good idea of how long each of the
photons takes to bounce and come back. If there’s something around the
corner, the photons come back sooner and arrive earlier in time,” says
Gupta. “We’re actually capturing and counting photons. Each image we
shoot has three or fewer photons in it. And we take lots of images very
quickly to create ‘streak’ images, which help us determine the distance
traveled by the photons in centimeters. Once we collect that data, we
can infer the basic geometry of the hidden object(s) and a 3D picture
are many potential applications for this technology. Among the more
simple and obvious are disaster recovery situations. “Say you have a
house collapsing and need to know if anyone is inside, our technology
would be useful. It’s ideal for use in nearly any disaster-type
situation, especially fires, in which you need to find out what’s going
on inside and around corners—but don’t want to risk sending someone
inside because of dangerous or hazardous conditions. You could use this
technology to greatly reduce risking rescue workers’ lives,” Gupta
also quite possible that the technology could be used as a form of
noninvasive biomedical imaging to “see” what’s going on beneath a
patient’s skin. That’s what the researchers plan to investigate now.
expects that it will likely be at least another five to 10 years before
the technology becomes commercially available—based on the typical
timeframe research and development (R&D) demonstrations take to
reach a product launch.
Source: Optical Society of America