Headquartered in Waterloo, Ontario, Zemax customer North builds products that change the way people see and interact with the world. Its latest offering is Focals smart glasses, launched last year, now selling in showrooms across North America. Focals are a pair of what North calls “everyday” smart glasses. The wearer can use them to text, get turn-by-turn navigation, manage their calendar, DJ their favorite playlist, and more. In the competitive smart glasses landscape, North stands out by focusing first on fit and fashion, creating a product that people actually want to wear. We’re thrilled that North’s team of optical designers used OpticStudio to help accomplish this task.

Creating Focals using OpticStudio

When the team at North began projector design for Focals, they found that in-house hologram models weren’t behaving as expected. They turned to OpticStudio’s hologram models. “We were able to create a freeform design for the hologram, figure out what aberrations were being introduced, then optimize for the best performance using OpticStudio,” said Vance Morrison, Project Co-Lead—Advanced R&D Display Systems at North. 

Modulation Transfer Function (MTF) is an important method of describing the performance of an optical system. MTF describes the contrast in the image of a spatial frequency presented in the scene being viewed.
Typically, it’s preferable to start with the default RMS Wavefront Merit Function in OpticStudio when optimizing a system to have a desired spatial frequency response since, as RMS wavefront error goes to zero, the MTF approaches its diffraction limited performance. Engineers can then switch to explicit MTF optimization operands as needed for a final adjustment of system performance. 

In North’s case, up against a diffraction limit due to the small size of the laser beam, and a scrappy, quick-moving, startup-style timeline, the team had to optimize on MTF and RMS spot size at the same time. Ian Andrews, Optical Design Lead at North, says, “We tried various methods in OpticStudio that would help optimize on diffraction limit. It wasn’t ideal, but we threw it on the Amazon server for a week and took advantage of multithreading. The fact that OpticStudio could be multithreaded was a big win for us.”

North’s freeform design for Focals ultimately has four surfaces with higher order polynomials with no symmetry and a scanning system, which required 150 configurations to be able to project without adding gaps. For that reason, everything needed to be scripted in MATLAB, so Morrison and Andrews say taking advantage of the ZOS-API was critical for the development of the smart glasses.

Finally, the team relied upon custom Gaussian filters and OpticStudio’s tolerancing capabilities to arrive at a final design. “OpticStudio was invaluable,” says Andrews. “We couldn’t have designed this by hand by any means. It was too non-symmetric.” 

About Focals

Each pair of Focals is custom-crafted in Waterloo, Ontario. Focals are custom-built glasses with a display only the wearer can see, allowing him or her instant access to the information they need and people they want to stay in contact with. Key features include visual summaries, smart text and emojis, voice-to-text capabilities including Alexa, navigation, calendar, and weather. Focals integrate technology within the silhouette of a traditional eyewear frame—so they are as fashionable as they are functional. 

What’s next for North

The team at North can’t share what it’s working on just yet. For now, it’s enjoying the positive reaction to Focals at trade shows and among the media. We look forward to hearing about what’s to come from this innovative company!