Lighting technologies will deliver a bright augmented-reality future (MAGAZINE)

Here’s an example of what I think the not-too-distant future will look like. Instead of having to physically log onto our laptops or tablets to engage in, say, a video conference, we will simply slip on a pair of sleek, stylish glasses and use them for contactless interactions with the online world.

The glasses will project lifelike graphical images that we can interact with by performing basic hand gestures. Suddenly, we’re not just conducting a video call with our colleagues. We’re in the same virtual room, with the ability to personally engage, shake hands, and much more, as if together at the office.

Another intriguing example is the ability to use global positioning system (GPS) apps hands-free, which could be very useful for sports such as running and biking. I could also see AR helping factory workers on the production line by projecting assembly instructions directly onto the parts they are working on, or bringing new levels of control to commercial and industrial building systems (Fig. 1).

Seeing the light

What exactly is needed to make this happen? First, we need smart, lightweight glasses that can perfectly overlay virtual images onto the real scene. The so-called combiner optics need to project a high-quality virtual image and also ensure an undisturbed see-through performance. These glasses must also be outfitted with the processing power and sensors to capture our gestures, recognize what we’re doing, and deliver the appropriate content.

Of course, we already have VR headsets today mostly used for gaming , but they’re far from perfect. They have issues of size, weight, and style, as well as other shortcomings. For the best experience, AR glasses must be able to project images with the correct brightness, color spectrum, image quality, and 3-D performance. They also need long battery life.

On the lighting and image-quality front, there are several competing technologies on the market, but there is still no one-size-fits-all solution. There is not a single technology that delivers on every key aspect. For instance, liquid-crystal displays (LCDs) are a mature, low-cost technology, but they have several drawbacks when applied to an AR environment, such as low resolution and poor color representation.

In contrast, digital light processing (DLP) and liquid-crystal-on-silicon (LCoS) lighting technologies offer good brightness and rich colors, but their system size might still be too large for mass deployment. Laser-based scanning mirror technology, for its part, offers a very small system size and attractive power efficiency — which is not the case for LCoS/DLP. LCoS/DLP are constantly flood illuminated with light, regardless of whether pixels are dark or bright. In addition, laser-based scanning mirror technology offers excellent colors and contrast, but the technology comes with a high price tag.

There are micro OLED and micro LED technologies that claim to address many core issues but, at least in the case of micro LEDs, the solutions may not be bright enough and are still in the process of being developed, so they are not yet ready for prime time (see an LEDs Magazine feature article on the prognosis for mini and micro LEDs, which addresses the display application specifically but also explains the fabrication challenges of such devices).

The path to critical mass

The jury is still out on the ultimate solution. But I don’t think that should be a roadblock for AR device manufacturers. Yes, it will take time before there is a complete solution, but there is no need for to wait for the perfect technology.

Manufacturers, for instance, can start with an AR lighting solution based on laser technology, because that is one of the most promising solutions today (Fig. 2). They can then migrate to next-generation lighting technologies such as micro LEDs once these are introduced to the market.