Turning any camera into a polarization camera
Metasurface attachment can be used with almost any optical system, from machine vision cameras to telescopes
Date:
March 18, 2022
Source:
Harvard John A. Paulson School of Engineering and Applied Sciences
Summary:
Researchers have developed a metasurface attachment that can turn
just about any camera or imaging system, even off-the-shelf systems,
into polarization cameras. The attachment uses a metasurface of
subwavelength nanopillars to direct light based on its polarization
and compiles an image that captures polarization at every pixel.
FULL STORY ========================================================================== Polarization, the direction in which light vibrates, provides a lot of information about the objects with which it interacts, from aerosols
in the atmosphere to the magnetic field of stars. However, because this
quality of light is invisible to human eyes, researchers and engineers
have relied on specialized, expensive, and bulky cameras to capture
it. Until now.
========================================================================== Researchers from the Harvard John A. Paulson School of Engineering and
Applied Sciences (SEAS) have developed a metasurface attachment that
can turn just about any camera or imaging system, even off-the-shelf
systems, into polarization cameras. The attachment uses a metasurface
of subwavelength nanopillars to direct light based on its polarization
and compiles an image that captures polarization at every pixel.
The research is published in Optics Express.
"The addition of polarization sensitivity to practically any camera will
reveal details and features that ordinary cameras can't see, benefiting
a wide range of applications from face recognition and self-driving cars
to remote sensing and machine vision, "said Federico Capasso, the Robert
L. Wallace Professor of Applied Physics and Vinton Hayes Senior Research
Fellow in Electrical Engineering at SEAS and senior author of the study.
In 2019, Capasso and his team developed a compact, portable camera
that used a metasurface to image polarization in a single shot. In
this research, the team explored how to generalize the concept of a polarization camera.
"After building the specialized polarization camera, we wanted to go more
in depth and investigate the design rules and trade-offs that govern
pairing a special polarization component with a conventional camera
system," said Noah Rubin, a graduate student at SEAS and co-first author
of the study.
To demonstrate those design rules, the researchers attached the
polarization metasurface to an off-the-shelf machine vision camera,
simply screwing it on in front of the objective lens, in a small tube
that also housed a color filter and field stop. From there, all they
needed to do was point and click to get polarization information.
The nanopillars direct light based on polarization, which forms four
images, each showing a different aspect of the polarization. The images
are then put together, giving a full snapshot of polarization at every
pixel.
The attachment could be used to improve machine vision in vehicles or
in biometric sensors for security applications.
"This metasurface attachment is incredibly versatile," said Paul
Chevalier, a postdoctoral research fellow at SEAS and co-first author of
the study. "It is a component that could live in a variety of optical
systems, from room-size telescopes to tiny spy cameras, expanding the application space for polarization cameras." The research was co-authored
by Michael Juhl, Michele Tamagnone and Russell Chipman. It was supported
by the Earth Science Technology Office (ESTO) of the National Aeronautics
and Space Administration (NASA) and by the U.S. Air Force Office of
Scientific Research under grant no. FA9550-18-P-0024. It was performed in
part at the Center for Nanoscale Systems (CNS), a member of the National Nanotechnology Coordinated Infrastructure (NNCI), which is supported by
the National Science Foundation under NSF award no. 1541959.
========================================================================== Story Source: Materials provided by Harvard_John_A._Paulson_School_of_Engineering_and_Applied
Sciences. Original written by Leah Burrows. Note: Content may be edited
for style and length.
========================================================================== Journal Reference:
1. Noah A. Rubin, Paul Chevalier, Michael Juhl, Michele Tamagnone,
Russell
Chipman, Federico Capasso. Imaging polarimetry through metasurface
polarization gratings. Optics Express, 2022; 30 (6): 9389 DOI:
10.1364/ OE.450941 ==========================================================================
Link to news story:
https://www.sciencedaily.com/releases/2022/03/220318104923.htm
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