New optical component enables AR/VR glasses without ‘bug eye’ effect

Researchers have combined freeform optics and a metasurface to deliver high-quality AR/VR glasses that are compact and easy to wear


he demand for high- resolution optical systems with a compact form

factor, such as augmented/virtual reality (AR/VR) displays, sensors and mobile cameras, requires the creation of new optical component architectures1. Researchers from the

University of Rochester’s Institute of Optics have therefore developed a novel technology that could help deliver compact and easy-to-wear glasses for AR/ VR. Such attributes are sought after by consumers, with the researchers’ technology enabling the development of optics that deliver high-quality imagery, while avoiding the creation of glasses with a ‘bug eye’ look. Reporting their work in Science

Advances, the researchers’ paper describes imprinting freeform optics with a nanophotonic optical element called a metasurface. The metasurface is a veritable forest of tiny, silver, nanoscale structures on a thin metallic film that conforms, in this advance, to the freeform

shape of the optics – realising a new optical component the researchers call a ‘metaform’. The metaform is able to defy

conventional laws of reflection, gathering the visible light rays entering an AR/VR eyepiece from all directions, and redirecting them directly into the human eye. Nick Vamivakas, one of the

paper’s authors and a professor of quantum optics and quantum physics, likened the nanoscale structures to small-scale radio antennas. ‘When we actuate the device and illuminate it with the right wavelength, all of these antennas start oscillating, radiating a new light that delivers the image we want downstream.’ Jannick Rolland, another

author of the paper, a professor of optical engineering and the director of the university’s Center for Freeform Optics, added: ‘Metasurfaces are also called “flat optics” so writing metasurfaces on freeform optics is creating an entirely new type of optical component. This kind of optical component can be applied to

A metaform is a new optical component that can combine with freeform optics to enable compact AR/VR headsets and eyewear

any mirrors or lenses, so we are already finding applications in other types of components, such as sensors and mobile cameras.’

Why weren’t freeform optics enough? The first demonstration of the technology required many years to complete, according to the researchers. The goal, of course, is to direct the visible light entering the AR/VR glasses to the eye, with the new device using a freespace optical combiner to help achieve this. However, when the combiner is part of freeform optics that curve around the head to conform to an eyeglass format,

not all of the light is directed to the eye. Freeform optics alone, therefore, could not solve this specific challenge. This is why the researchers had

to leverage a metasurface to build a new optical component. ‘Integrating these technologies,

“Integrating these two technologies, freeform and metasurfaces... and leveraging that to get a good image was a major challenge”

Lidar-enabled AR heads-up display could improve road safety

Researchers from the universities of Cambridge, Oxford and University College London (UCL) have developed a lidar-based augmented reality (AR) heads- up display for use in vehicles. Tests on a prototype version of the technology suggest that it could improve road safety by ‘seeing through’ objects to alert to potential hazards without distracting the driver. The technology uses lidar data

to create ultra-high-definition holographic representations of road objects which are beamed directly to the driver’s eyes,

28 Electro Optics June 2021

instead of the 2D windscreen projections used in most head-up displays. While the technology has not

yet been tested in a car, early tests, based on data collected from a busy street in central London, showed that the holographic images appear in the driver’s field of view according to their actual position, creating an augmented reality. This could be particularly useful where objects such as road signs are hidden by large trees or trucks, for example, allowing the driver to ‘see through’ visual obstructions. The results are

reported in the journal Optics Express. ‘Head-up displays are being incorporated into connected vehicles, and usually project information such as speed or fuel levels directly onto the windscreen in front of the driver, who must keep their eyes on the road,’ said lead author Jana Skirnewskaja, a PhD candidate from Cambridge’s Department of Engineering. ‘However, we wanted to go a step further by representing real objects as panoramic 3D projections.’ The researchers scanned

Image based on lidar data (leſt), converted to a hologram (right)

@electrooptics |

J. Skirnewskaja et al. / University of Cambridge

University of Rochester illustration / Michael Osadciw

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