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Harvard University researchers have innovated a compact single-shot polarization imaging system that simplifies traditional setups and expands applications in medical, AR, and smartphone technology, with enhanced imaging capabilities that integrate real-time and machine learning . Credit: SciTechDaily.com
Scientists have developed a compact, single-shot, complete polarization imaging system using metasurfaces.
Think of all the information we get based on how objects interact with the wavelengths of light, or colors. The color tells you if the food is safe to eat or if the metal piece is hot. Color is an important diagnostic tool in medicine, helping doctors diagnose diseased tissue, inflammation, or blood flow problems.
Companies have invested heavily in improving color in digital imaging, but wavelength is just one property of light. Polarization (how electric fields oscillate as light propagates) is also rich in information, but polarization imaging has been largely confined to tabletop laboratory environments, and wavelength imaging on thick rotating mounts. It relies on traditional optical systems such as plates and polarizers.
A breakthrough in compact polarization imaging
Now, researchers at Harvard's John A. Paulson School of Engineering and Applied Sciences (SEAS) have developed a compact, single-shot polarization imaging system that can provide a complete picture of polarization. This imaging system uses only two thin metasurfaces and offers enormous potential for polarization imaging for a variety of existing and emerging applications, including biomedical imaging, augmented and virtual reality systems, and smartphones. can be released.
This study natural photonics.
A unique species of beetle, Chrysina gloriosa, has a unique response to circularly polarized light reflecting off its shell. This chiral response is precisely imaged by the new system. Credit: Aun Zaidi/Harvard SEAS
“With no moving parts or bulk polarization optics, this system powers applications in real-time medical imaging, materials characterization, machine vision, target detection, and other critical areas,” Robert L. Wallace Federico・Mr. Capasso said. Vinton Hayes, professor of applied physics and senior research fellow in electrical engineering at SEAS, is the paper's lead author.
In previous research, Capasso and his team developed a first-of-its-kind compact polarization camera to capture so-called Stokes images, or images of polarization signatures reflecting off objects, without controlling the incident illumination. did.
active polarization imaging
“Just as the shading and color of an object appear differently depending on the color of the incident illumination, the polarization properties of an object depend on the polarization profile of the illumination,” says Aoun Zaidi, who just completed his Ph.D. at Kapasso University. says Mr. Group and first author of paper. “In contrast to traditional polarization imaging, 'active' polarization imaging, known as Mueller matrix imaging, can capture the most complete polarization response of an object by controlling the incident polarization.”
Currently, Mueller matrix imaging requires a complex optical setup with multiple rotating plates and polarizers that sequentially capture a series of images that are combined to achieve a matrix representation of the image.
The simplified system developed by Capasso and his team uses two very thin metasurfaces. One illuminates the object and the other captures and analyzes the light on the other side.
The first metasurface produces what is known as polarized structured light. In this light, the polarization is designed to vary spatially in a unique pattern. When this polarized light is reflected or transmitted by the object being illuminated, the polarization profile of the beam changes. That change is captured and analyzed by his second metasurface, and the final image is constructed with her single shot.
This technology enables real-time advanced imaging, which is important for applications such as endoscopic surgery, facial recognition for smartphones, and eye tracking for AR/VR systems. It can also be combined with powerful machine learning algorithms for applications such as medical diagnostics, materials classification, and pharmaceuticals.
“We have designed a single system that integrates two seemingly separate disciplines, structured light and polarization imaging, to obtain the most complete polarization information, which is traditionally required for such systems. The use of nanoengineered metasurfaces to replace many of the components greatly simplifies their design,” said Zaidi.
“Our single-shot, compact system provides a viable path to widespread adoption of this type of imaging to power applications that require advanced imaging,” Capasso said. Masu.
Reference: “Metasurface-enabled single-shot and full Muller matrix imaging” Aun Zaidi, Noah A. Rubin, Maryna L. Meretska, Lisa W. Li, Ahmed H. Dorrah, Joon-Suh Park, Federico Capasso, 2024. May 2, natural photonics.
DOI: 10.1038/s41566-024-01426-x
Harvard University's Office of Technology Development secured intellectual property related to this project from Prof. Capasso's lab and licensed the technology to Metalens for further development.
The study was co-authored by Noah Rubin, Marina Meretzka, Lisa Lee, Ahmed Dohler, and Junso Park. This research was supported by the Air Force Office of Scientific Research (award number FA9550-21-1-0312), the Office of Naval Research (ONR) (award number N00014-20-1-2450), the National Aeronautics and Space Administration (NASA) award numbers 80NSSC21K0799 and 80NSSC20K0318, and National Science Foundation award number ECCS-2025158.
