Researchers develop new polarization-based imaging tech with 3D facial recognition potential
Researchers have developed a new camera technology based on sensing polarization which could have major implications for biometric facial recognition and machine vision applications, Eurasia Review reports.
The new highly-compact, portable camera that can capture polarization from a single image significantly opens up the potential application of polarization, which has so far only been observable with bulky, expensive cameras that rely on moving parts. The camera developed by the team from the Harvard John A. Paulson School of Engineering and Applied Sciences (SEAS) is approximately two inches, and could potentially be deployed in numerous settings, such as in autonomous vehicles.
The team, led by senior author and Robert L. Wallace Professor of Applied Physics and Vinton Hayes Senior Research Fellow in Electrical Engineering at SEAS Federico Capasso, published its findings on the direction of light vibrations, which are invisible to the human eye, to the journal Science.
“Polarization is a feature of light that is changed upon reflection off a surface,” says Paul Chevalier, a postdoctoral fellow at SEAS and co-author of the study. “Based on that change, polarization can help us in the 3D reconstruction of an object, to estimate its depth, texture and shape, and to distinguish man-made objects from natural ones, even if they’re the same shape and color.”
The researchers leveraged specially patterned camera pixels, integrated in a simple device with a metasurface, which is a nanoscale structure that interacts with light at wavelength scale, according to the report. An array of subwavelength-spaced nanopillars direct light based on its polarization, allowing the light to form four images, which taken together produce a full image of polarization for every pixel.
With a lens and a protective case attached, the device is about the size of a small lunch box, according the Review. The researchers tested it on injection-molded plastic objects to reveal defects, in outside environments on car windshields, and demonstrated visualization of the 3D contours of a face.
“This technology could be integrated into existing imaging systems, such as the one in your cell phone or car, enabling the widespread adoption of polarization imaging and new applications previously unforeseen,” says Capasso Lab graduate student and research paper co-author Noah Rubin.
U.S. Army researchers developed a method of polarimetric-thermal imaging in 2016, though the technology has not been commercialized.