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Photonics Europe Digital Forum: Schott ready to ramp higher-index glass for AR

07 Apr 2020

Glass and optics giant’s ‘RealView 1.9’ material for augmented reality (AR) waveguides broadens field of view in consumer devices.

Schott, the Germany-headquartered manufacturer of glass optics, says it is ready to mass produce its latest high-index material - designed to improve the augmented reality (AR) experience in consumer devices.

Presenting the latest advances in a virtual format for the SPIE Photonics Europe Digital Forum, which is taking place this week as a replacement for the “live” event in Strasbourg, Schott’s product manager for AR, Berthold Lange, said that Schott was now able to produce 1.9-index glass on 300 mm-diameter wafers.

Known as “RealView 1.9”, the large format means that 25 individual waveguides - each measuring 50 mm by 36 mm - can now be produced on a single wafer, pushing economies of scale to a new level. The figure compares with ten waveguides per 200 mm wafer, and just four on 150 mm-diameter material.

Transmission trade-off
The higher-index material is needed to broaden the field of view of AR glasses and headsets, but comes with a trade-off of lower light transmission, particularly at shorter wavelengths.

“Just increasing the refractive index of the glass is not the simple solution,” noted Lange in his presentation. “Challenges like transmission, especially at short wavelengths, melting dimensions, and mechanical properties [of the glass] have to be resolved.”

Those challenges led to the company’s collaboration with waveguide specialist WaveOptics, wafer production equipment firm EV Group (EVG), and polymer developer Inkron. That effort has now resulted in the availability of the high-index material and waveguides that can be produced at the kind of volume required to meet consumer pricing targets.

Delving into the technical requirements for the waveguides, Lange explained how the total internal reflection angle was a critical factor that limits the ultimate field of view of the AR display.

Field of view
With the latest approach, first revealed by Schott earlier this year at SPIE’s Photonics West event, consumer-level AR designs are able to offer a field of view of 65°.

That followed fabrication of an initial demonstrator at EVG’s nanoimprint lithography development center, using the Austrian firm’s proprietary wafer processing equipment for 300 mm-diameter material.

Inkron’s high refractive index resin is then combined with the “RealView” substrate material, providing the foundation for WaveOptics’ waveguide design - said to offer the widest range of fields of view, combined with a very large eye-box onto which images can be overlaid, and delivering vibrant colors alongside high contrast.

Back in February, UK-based WaveOptics won a Photonics Prism Award for its development of those waveguides.

• The SPIE Photonics Europe Digital Forum takes place online 6-10 April. To view presentations and manuscripts, and interact with speakers, visit the virtual event's dedicated web site.

SPECTROGON ABHÜBNER PhotonicsTRIOPTICS GmbHLASEROPTIK GmbHIridian Spectral TechnologiesAlluxaHyperion Optics
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