Smart glasses
Smart glasses could be the consumer electronics industry’s next big hit, but companies first need to come up with designs that people want to wear. Squeezing so much new technology into a tiny product requires ingenuity, innovation, and cutting-edge manufacturing capabilities.
Jonathan Ward, June 2024
Digital products tend to get smaller and more personal over time. The computer on your desk led to the laptop in your bag, then the smartphone in your pocket. Today, the watch on your wrist may be a powerful computing device too, capable of making calls, displaying messages, or monitoring your vital signs. After a slow start, smartwatches became the first mass-market “wearable” devices.
Now the technology industry has a new wearable product in its sights: the spectacles on your face. “Smart glasses” are a diverse category of digital devices. Broadly encompassing any form of spectacles or goggles that include electronic components, they range from relatively simple products that incorporate headphones or a camera, all the way to advanced headsets equipped with high-resolution displays and audio systems for immersive virtual reality experiences.
Each of these products has found its niche, but none has reached the level of adoption achieved by smartphones, with sales of more than 1.3 billion units per year according to research company Gartner, or even of smartwatches, with sales of around 180 million units, according to research company CCS Insight. Apple, the company that did so much to popularize smartphones and smart-watches, entered the smart glasses market this year. The company’s Vision Pro won’t replace your current favorite spectacles or sunglasses, however. It is a high-end headset intended to be used for virtual reality applications or as a replacement for a large computer monitor or TV screen.
Technology companies haven’t yet achieved their goal of smart glasses with true mass market appeal, but they know where to look. The most promising area of development today is products with “augmented reality” (AR) capabilities. These are glasses that allow the user to see the real world in front of them overlaid with relevant digital data. The main applications for these products are in industry.
Bühler, for example, offers a remote service and maintenance solution for its customers called BühlerVision. Using an AR headset equipped with a camera, customers use BühlerVision to communicate with a technical support specialist who can explain the steps necessary to complete a task.
Smart glasses are proving their use in professional settings. But for smart glasses to succeed in the mainstream, companies need to package these capabilities in a format that looks much more like conventional spectacles. That is a formidable technical challenge, requiring the components within the glasses to be made significantly smaller, more robust, and at a lower cost than current-generation products.
Our work in this sector spans our business in semiconductors, precision optics, and ophthalmics.
Steffen Runkel, Head of Business Unit optics at Bühler
“There are several different technologies in development for these next-generation smart glasses,” says Dr. Steffen Runkel, Director of Business Unit Optics at Bühler Leybold Optics. “But they all contain a few basic components. First, you have the microdisplay, or light engine, which creates the image. That is a tiny component concealed within the frame of the glasses. Then you have the optical engine, which uses a combination of lenses and waveguides to project the image onto the glasses, correcting it to suit the needs of wearer’s eyesight. Finally, you have the ophthalmic components: the main lenses on the glasses, which must perform a dual role, as optical lens and display screen.”
Bühler is working with manufacturers and institutes on the development of the required optical coating solutions for all these systems for smart glasses. “Our work in this sector spans our business in semiconductors, precision optics, and ophthalmics,” explains Runkel.
The Bühler contribution to the smart glasses revolution is focused on the specialized coatings and surface treatments needed to deliver crisp images in a tiny format. Those coatings are used to filter light at specific wavelengths, for example, or to increase the transmission of light within the optical engine. Microscopic etching into lenses or lens surface coatings is used to create grids of “pixels” that will reflect light to the wearer’s eye.
Individual components within the system may require a stack of multiple coatings to achieve the desired combination of properties. “Even the lenses of conventional glasses may have six or eight coating layers, designed to prevent unwanted reflections, absorb certain light wavelengths, shed dirt, resist fingerprints, and protect the lens from scratches,” explains Klaus Herbig, Head of Market Segment Precision Optics at Bühler Leybold Optics. “In smart glasses, there may be 12 layers or more.”
Even the lenses of conventional glasses may have six or eight coating layers, designed to prevent unwanted reflections, absorb certain light wavelengths, shed dirt, resist fingerprints, and protect the lens from scratches.
Klaus Herbig, Head of Market Segment Precision Optics at Bühler Leybold Optics
Smart glass applications also place significant demands on coating quality. Within the optical engine, layers must be precise and consistent to keep the image focused. And a projected image changes the way users see their lenses, too. “With conventional glasses, you are always looking beyond the lens, so you might not notice tiny imperfections in the surface,” explains Runkel. “With smart glasses, the projection comes from the lens itself, and you notice any problems.”
The pursuit of optical perfection is encouraging lens makers to adopt new technologies, for example by replacing liquid-based, anti-scratch coatings with “dry” vacuum coatings that can be applied in thinner and more consistent layers. Manufacturing systems matter too, with production machines working in a cleanroom environment to reduce the risk of contamination.
Advanced coating technologies and sophisticated coating machines are helping companies to overcome the technical challenges of smart glasses. But they still need to address the cost.
“Producing such advanced products at reasonable cost requires highly automated, high-volume manufacturing,” explains Runkel. “We have worked with our customers to develop coating systems that work for prototypes and small batches. Now we are developing a new generation of equipment that will achieve the same quality and consistency in mass production.”
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