A new technology for fast imaging by holography allows you to see the invisible in images obtained by a camera, such as objects that are behind a corner, in fog or under the skin, states a statement released this Wednesday by Northwestern University (Illinois, USA).
The invention takes advantage of visible or infrared light that is indirectly scattered on hidden objects to reveal and reconstruct, when this light returns to the camera, things that are outside the immediately visible area. The walls turn to mirrors for these rays and the apparatus perceives the multiple reflections of each one of them.
The camera captures images of large areas with sub-millimeter precision and is thus able to see through skin, even the smallest capillaries in operation. On the other hand, this technique has a high temporal resolution, something that allows you to clearly capture moving objects, such as the heart that beats behind the ribs, which in this case do not obstruct vision.
The method was developed under the auspices of the DARPA agency, part of the US Department of Defense, but the university does not specify how it will be applied to combat or other military missions. For the authors, their priority potentials are the non-invasive obtaining of medical imaging, automotive early warning navigation and industrial inspection in compact spaces. Other potential applications are endless, highlights the research team.
It’s like passing light through the palm of your hand
Seeing what’s behind a corner and imaging an organ within the human body may seem like two very different challenges, but the lead author of a study In this regard, Florian Willomitzer, explained that they are actually closely related. Both of them have to do with the scattering of light, which hits an object and spreads so that the direct image of the object is no longer visible.
“If you’ve ever tried to shine a flashlight through your hand, then you’ve put this phenomenon to the test,” Willomitzer said. Although part of the flashlight’s brightness is perceived on the other side, it would appear that, “theoretically, the shadow of the bones should also be projected.” “However, the light that passes through the bones spreads into the tissue in all directions, completely erasing the image of the shadow,” he added.
The inventors call this method ‘synthetic wavelength holography’, a term that refers to the use of two lasers and the combination of their reflected light with the aim of not having to resort to fast detectors, which are capable of identifying the minute nuances in the speed of each ray of light but they are very expensive. Instead of these miniscule measurements, the camera assemblesthe entire light field of an object in a hologram and recreates, from it, the three-dimensional shape of this object in its entirety.
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