Optical metasurfaces create tiny polarisation camera

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Credit: Science and Harvard SEAS

Scientists at the Harvard School of Engineering and Applied Sciences (SEAS) have developed a compact snapshot polarisation camera based on diffraction gratings containing nanoscale structures.

The camera is able to acquire images of the full polarisation state at each pixel, with no traditional polarisation optics and no moving parts.

The work, published in Science, uses diffraction gratings with dielectric metasurfaces, in which the nanoscale structures on the surface of the gratings give tuneable polarisation control. The grating is flat and monolithically integrated into the imaging system.

The researchers named remote sensing, atmospheric science, machine vision, and onboard autonomous vehicles as areas where the polarisation camera might be used, and where complexity of current systems might otherwise prove prohibitive. 

As reported by Harvard SEAS, the device is about 2cm in length; with an attached lens and protective case, the device is about the size of a small lunch box.

‘This technology could be integrated into existing imaging systems, such as the one in your cell phone or car, enabling the widespread adoption of polarisation imaging and new applications previously unforeseen,’ commented Noah Rubin, first author of the paper. 

The lab-based prototype lidar system that the research team built captures megapixel-resolution depth maps using a commercial digital camera. (Image credit: Andrew Brodhead)

31 March 2022

Four imaging examples, two indoor (left) and two outdoor (right). These examples primarily explore the polarised nature of specular (Fresnel reflection), in which unpolarised light is partially polarised perpendicular to the plane of incidence upon reflection. Credit: Capasso Lab/Harvard SEAS

23 March 2022