Glass wafers in holder image

The German specialty glass maker Schott claims that its RealView product can achieve a significantly better field of view for waveguide-type AR glasses than alternatives on the market. [Image: Schott]

In the technological rivalry to make the best see-through glasses for augmented reality (AR), a key battleground is improving field of view (FOV). The German specialty glass manufacturer Schott has recently introduced a new product into that industrial fray: a “smart glass” that it has trade-named Schott RealView.

The company claims that the glass—which it says leverages optical-glass manufacturing techniques, rather than the sheet-glass production common for providers of AR glass—can sport a substantially greater refractive index than conventional AR glasses, yielding a broader FOV. Schott maintains that the product also boasts a tenfold improvement in surface flatness, to boost image quality. And the company says it’s ready to roll out manufacturing at scales to meet existing and future demand.

Waveguide ready

The Schott product is designed particularly to address the waveguide-type AR glasses that have emerged as a focus of development in the past several years. These glasses work by passing the AR information, in red, green and blue channels, lengthwise through the lenses from the microdisplay optics to the eye, which recombines the three channels into an image that is overlaid on the real-world view. The lenses of the AR glasses thus act as see-through waveguides, piping through the light from the AR optics via total internal reflection.

In such a scheme, a high refractive index for the AR glass “basically translates directly into a wide field of view,” according to Rüdiger Sprengard, head of AR operations at Schott, who spoke with OPN about the new glass. That’s because a high refractive-index contrast with air implies a higher acceptance angle for the total internal reflection, which means that more light can be confined in the waveguide for a longer distance. The standard index for existing display glasses in the marketplace, he observes, is “roughly 1.5—not good enough,” he says, “to generate a wide field of view.”

Building on optical-glass techniques

By contrast, the Schott RealView glass, according to the company, can boost the index to 1.6 to 2.0 for mass-producible AR glass—providing, according to a company press release, “the first opportunity to expand the FOV [in AR devices] almost to the limits of human peripheral vision.” Schott has also reportedly achieved a tenfold increase in planarity, or surface flatness, in the RealView wafers. This can boost image quality, according to Sprengard, by eliminating distortions and, in particular, by allowing the red, green and blue channels from the waveguided light to be recombined in the eye with “spatial perfection.”

Glass manufacturing scene

To achieve a high refractive index, the RealView product relies on manufacturing techniques for optical glass, rather than the sheet production that the company says is used for typical AR glasses. [Image: Schott]

To get to these specs, Sprengard says, Schott relied on its manufacturing expertise in high-end optical glass. The sheet-glass manufacturing techniques used to fashion glass wafers for most AR applications, he says, are limited to a narrow range of chemical compositions that “are not compatible with high-refractive-index glasses … So from that perspective, we’re constrained to use manufacturing processes for optical glass.” Sprengard believes that the company’s long-term experience both in the technology of such glasses and in their mass manufacture could prove to be an advantage. “The reason that we still exist in a highly competitive world market,” he says, “is basically technology.”

Two market phases

The combination of better planarity and a wider FOV, Sprengard maintains, could add up to a more immersive experience, extending into the user’s peripheral vision. One easy-to-envision example is in gaming: “If you’re in a [first-person] shooting game,” he says, “you want the monsters to appear anywhere,” not just directly in front of you.

But Schott is envisioning a broader market than just monster-slayers. “We’re preparing for two market phases,” Sprengard says. The current stage, he continues, is apt to be dominated by industrial, educational or other applications “for which there’s a commercial justification for using the glasses.” That market space, he suggests, could add up to anywhere from 100,000 to 1 million devices per year.

The second phase, which Sprengard thinks might gain traction in the next several years, would be driven more by consumer applications, and could ultimately amount to “very roughly, 25 million pieces per year.” He says that Schott is already tooled up to serve the existing market, and that it has “made preparations to be part of the first wave of consumer-type products” as those start to emerge in coming years.

Whatever the exact timing, Sprengard is convinced that the AR next wave is real, and that it’s coming to a pair of glasses near you. “Based on the things I’ve experienced—and obviously I have seen a lot of things in the lab that are far from out in the marketplace yet—I would say that this really is opening up a new world in how we perceive and interact,” he says. “It’s not just more of the same … I’m very convinced that the impact will be there at a broad scale.”