By updating centuries-old technology, a small team of 3M scientists has sparked a revolution in virtual-reality headsets.

In the early 2010s, a handful of 3M scientists were given an open-ended mission: apply the company's extraordinary array of technologies to a big, emerging opportunity. "3M likes to discover opportunities that are technically very challenging, that require large-scale manufacturing and where being early creates a strong competitive advantage," explained Erin McDowell, AR VR Business Development Senior Manager. "That's what we were looking for."

One of the first opportunities explored by the team was in specialized light-emitting diodes, or LEDs, as a light source for wearables. "At the time, we decided that LEDs weren't that attractive of a business for 3M," recalled Tim Wong, Advanced Product Development Specialist. "It was clear to us that wearables were going to be big. So, we shifted our focus and asked ourselves, 'Where does this market need our particular set of skills.'"

Augmented reality — or AR, which is the overlaying of digital images or information on the real world — was an obvious answer. During his early studies of wearables, Wong created a list of 30 ways to create an AR device, "Almost all of them needed mirrors and beam-splitting polarizers to form the image," Wong said. "“What if instead we used our unmatched ability to make reflective films and polarizers?"

An old technology becomes new

The key was 3M's expertise in multilayer optical films (MOFs), which were initially developed in the early 1990s and were one of the primary enabling technologies in the development of laptops and other portable digital displays. 3M had since refined the design and manufacturing processes, and could produce, at scale, films with the thickness of a sandwich bag containing 300 or more ultra-precise layers. Some layers were as thin as 15 nanometers — much less than a wavelength of light.

Another shift in focus came in 2013 at CES, the annual trade show of the Consumer Technology Association. As former 3M corporate scientist Andy Ouderkirk — one of the originators of MOF technology—was demonstrating the company's emerging AR technology, he was repeatedly asked if the technology could somehow be adapted to virtual reality (VR).

"It was exciting. We saw right away that it was an unsolved problem among multiple customers," McDowell said. "They kept asking if we could use our films to create a much thinner headset, and we knew almost immediately that we could."

Wong agreed.

"VR optics are way easier because they are occluded, unlike the see-through optics of AR. MOF reflectors have a lot to offer here. To achieve a wide field-of-view, most VR headsets today use a large display paired with a Fresnel lens," he said. "This combination requires a long focal length which essentially results in a bunch of dead air space between the lens and the display, hence the large and bulky headsets of first-generation VR. But you can get even better resolution and magnification with folded optics using MOFs, which are lighter and thinner than a Fresnel lens, and can use a smaller display panel, further reducing headset size."

This is where the update of a centuries-old technology comes into play.

3M's folded optics are a modern interpretation of a technology first explored by Isaac Newton when he used mirrors to collapse the light path of early telescopes. Skip more than 300 years to the 1970s and researchers recognized they could improve the optics of many devices by replacing the mirrors with birefringent reflective polarizers. Combined with a beam splitter, these polarizers could provide compact design, high resolution, and a wide field of view — in theory. In practice, conventional wire-grid or cholesteric reflective polarizers weren't efficient enough to produce images with acceptable quality. It wasn’t until the 1990s, when 3M was creating polarizers at scale for laptops and other devices, that the technology finally met the high efficiency requirements of folded optics.

From concept to reality

Within a few months of that 2013 trade show, Wong and Ouderkirk were able to build a prototype VR headset using 3M's MOF-based reflective polarizers. It was a crude, proof-of-concept demonstration of folded optics that got a chilly reception at the 2014 annual meeting of the Society for Information Display.

"Customers uniformly said it wouldn't work," McDowell said, "They said, 'You won't be able to get enough contrast ... but, hmmm, on the other hand, it is pretty good. But you'll have ghosts and it'll be too expensive. But on the other hand, it is really pretty good.’ That told us we were on the right track, but we had to be a lot better."

This was followed by the unglamorous work of perfection – five years of what scientist and laboratory manager Susan Kent called the trench warfare of steady, incremental, iteration-upon-iteration development, optimization, and invention to come up with a prototype that was good enough to convince customers that folded optics would give them the form factor and resolution they wanted in a headset.

Collaboration from Within

The team started pulling in specialists from throughout 3M. "Over the years, 3M had created businesses that relied on imaging optics, such as pocket-sized pico projectors and huge projection television components," said Kent. "We could draw on scientists and manufacturing engineers who'd worked on molding components for those projects. We needed expertise in imaging and optics modeling, so we brought in experts who'd worked in 3M's dental imaging business."

The team also needed to develop specialized technology for integrating its films with the curved lenses it was creating. For this, they called on scientists in 3M's corporate research lab, who were highly versed in the problems of applying automotive and architectural graphic films to the complex curves of a fender or artistic light fixture.

The results began to attract attention. "One of the benefits of early-stage technology development is that you have pretty regular contact with your potential customers," McDowell said. "They began to believe in what we were doing."

The result was revealed at CES in 2020.

"This time, the response was, 'Oh…. Wow!'” said Kent. "There was this widespread, general acknowledgment that folded optics technology had arrived. One customer summed it up well with, 'Seeing is believing.' No more doubts ... it's going to happen."

Virtual reality becomes reality

As of mid-2021, 3M is producing the folded optics for high-resolution VR headsets. For customers who prefer headsets with curved lenses, 3M will supply the folded optics integrated with the lens; for customers who prefer flat lenses, 3M will provide standalone films.

As for the future? "We have made tremendous progress, but we know we have to get better and we will," McDowell said. "This is really more of a promise of what can be done."

As work continues with folded optics, 3M is also exploring opportunities for improving the VR experience. One approach is to incorporate small motors that will allow the components within the headset to move as the user's eye looks into the distance—a technique for reducing the sense of vertigo that some users experience.

And there is much more that 3M scientists think they can contribute. "This is such a new field," McDowell said. "There is a lot of work to be done not only in the optics but also in the displays and sensors and the look and feel of the headsets. Optimizations go on and on. Virtual reality is a great opportunity for a science and technology company like 3M, and we're committed to exploring it all."

Visit go.3M.com/arvr to learn more about 3M's AR/VR solutions and view animations demonstrating how the folded optics lens work.