Holographic Images: This High-Resolution Camera Can Capture Hidden and Fast-Moving Objects

Researchers at Northwestern University recently developed a high-resolution camera that can produce holographic images.

As indicated in an Engineering and Technology report, this highly technological camera can "see around corners and through scattering media," like fog, skin, and possibly, even the human skull.

This new approach called "synthetic wavelength holography" works by indirectly dashing coherent light onto unseen objects, which is then scattering again, and moving back to a camera.

From there, an algorithm is rebuilding and scatters light signals to show the hidden objects. Because of its temporal resolution, the approach has the potential as well, to capture fast-moving objects like a beating heart through the chest, or fast cars around a street corner.

'Line-of-Sight' Imaging

This somewhat new study field of capturing objects behind sealing or scattering media is also known as "line-of-sight" imaging.

Compared to associated imaging technologies, this method by the Northwestern researchers can quickly capture full-field images of large sites with submillimeter accuracy.

With this resolution level, according to the researchers, the computational camera could possibly image through the skin to view even the smallest capillaries at work.

While the approach has evident potential for non-invasive medical imaging, early-warning navigation systems for vehicles, and industrial inspection in securely confined areas, the study authors believe, possible applications are endless.

Use of Visible or Infrared Light

According to the study's first author, Florian Willomitzer from Northwestern, their technology will lead to a new wave of imaging capabilities.

The first author of the study published in Nature Communications added, their current sensor models are using visible or infrared light, although the principle is universal and could be expanded to other lengths of waves.

For instance, explained Willomitzer, the same approach could be employed to radio waves for the exploration of space or "underwater acoustic imaging." He also said, it can be used in many areas and they've only scratched the surface with their technology.

Being able to see around a corner against imaging an internal organ of the human body might appear like quite different challenges, although the first author said, they are in fact, closely related.

Both are dealing with scattering media, in which the light is heating objects and scattering in a way that an object's direct image can no longer be seen.

Willomitzer explained, if one has ever tried shining a flashlight through his hand, he has then experienced the phenomenon.

Speed of Light

He explained further, one sees a bright spot on the other side of his hand, although theoretically, there should be a shadow cast by his bones, showing the structure of the bones.

Rather, the light that's passing the bones is getting scattered within the tissue in all directions, totally blurring out the shadow image.

The objective then is to interrupt the scattered light to rebuild the inherent information about its travel time to expose the hidden object, SciTechDaily specified in a similar report. This then presents its own challenge.

Willomitzer continued, nothing is quicker than the light's speed, and thus, one who wants to measure the travel time of light with high accuracy will require extremely fast detectors. However, such detectors are quite expensive.

Eliminating the Need for Fast Detectors

Northwestern Now reported, to eliminate the necessity for fast detectors, the study authors merged waves from a pair of lasers to generate a synthetic light wave that can be particularly tailored to holographic imaging in different scenarios of scattering.

Williomitzer explained, if one can capture the whole light field of an object in a hologram, he can then, reconstruct the three-dimensional shape of an object in its entirety.

He added they do this holographic imaging around a corner or through scatters, with synthetic waves, rather than the normal waves of light.

Related information about cameras that see through walls is shown on Fw: Thinking's YouTube video below:

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