There’s Groundbreaking Waveguide Tech Inside Meta’s $800 AR Glasses But Don’t Count on Fixing Them

If wearables are going to replace our phones, they need to age as gracefully as our favorite pair of glasses. Replaceable batteries when they fade, swappable nose pads when they get gross, new hinges and lenses when life inevitably scuffs them up. That’s what true repairable wearables should look like.

We’ve just dug into Meta’s new Ray-Ban Display glasses (to be clear, that is, the Meta Ray-Ban Display glasses, not the Ray-Ban Meta AI glasses). These glasses are a glimpse of that wearable future… just not the repairable part. These are, hands down, some of the most advanced augmented reality consumer glasses ever built. They look like a slightly chunkier version of Ray-Ban Metas, but they offer a lot more tech: hidden inside is a micro-projector that beams full-color images through the lenses, painting a 600×600-pixel augmented reality display in the lower right of your vision.

We’re excited about some repair possibilities with AR glasses like this: Imagine pulling up a repair guide that follows your voice commands while you fix something, guide visible the whole time as you’re doing the repair. That’s the dream.

Until, of course, something breaks in the glasses themselves. Don’t count on fixing anything in these $800 glasses.

The Battery Problem

Let’s start with the simplest repair: a dead battery. The battery in these glasses is expected to last about six hours “with mixed use.” If you’re wearing them off and on all day, you could conceivably go through a couple of battery cycles in a day, which will wear the battery down faster.

Battery repair isn’t totally impossible here, provided you can get your hands on a replacement battery (which Meta hasn’t yet made available), and you’re handy with a hot air station. Each arm of these glasses is sealed shut with glue, making entry a game of heat, patience, and luck. Once inside, we found a 960 mWh battery, a small upgrade over the Oakley Meta HSTN’s 856 mWh pack, but still not easily replaceable. 

Though there’s some adhesive under that battery, the real issue is the seam on the arm of the glasses themselves. We’re a little disappointed to still see that the arm is glued together, no clips, and no good option for resealing the glasses if you perform a repair. The glue feels like overkill for an IPX4 water rating, and one careless move can shear off the delicate ribbon cable underneath.

It’s easy to imagine a future where the battery arm could be swapped as a module. For now, though, every recharge cycle brings these closer to the end of their wearable life.

Take a peek at that battery arm assembly in this interactive CT scan, courtesy our Lumafield Neptune CT scanner:

The Science Behind the Optical Magic

How about the lenses? When you shell out a bunch of cash for a fancy pair of frames, you might want to just swap out a scratched lens instead of replacing the whole kit and caboodle. But in this case, the right lens is thick with multiple layers of high-precision coated glass.

So, how do these glasses show a little screen floating in the middle distance? AR optics expert Karl Guttag helped us unpack the magic. There are two main pieces to the secret: One, there’s a little projector in the right arm. Two, the glass is very carefully shaped to bend the light. 

That projector is special, but it’s actually a variation that has been around since the ‘90s. At its heart is a display that works similar to LCD TVs and computer monitors: all of them run on a grid of mirror-electrodes that control liquid crystal molecules. 

When those crystals get hit with an electrical current, they twist and change the polarization of light going through them.

The Display Glasses use a liquid crystal on silicon (LCoS) device with a grid of 600×600 pixels, bouncing the light from three LEDs off these twisting crystals, then passing them through a series of lenses, mirrors, and a polarizing beam splitter that routes light based on polarization.

A lot of AR glasses manufacturers like LCoS because it’s small for a given resolution, is much less expensive than LEDs, and doesn’t require a lot of power.

We saw it in Google Glass back in 2013 and Magic Leap in 2016 and 2022. The prettiest part of the system under our Evident DSX-2000 microscope is probably the homogenizer, a little array of lenses that combine the red, green, and blue LEDs and diffuse them.

But the thing that makes these glasses special is actually an advancement in even older tech: glass-making. 

A Very Fancy Piece of Glass

Inside the glass, a series of partially reflective mirrors bounce some of the light out to your eyes at specific angles. The light first hits these vertical pupil expanders that replicate the light vertically. 

Next, the light passes through the lens to this series of partially reflective mirrors (virtually invisible to the naked eye at most angles). Each of these mirrors reflects approximately 5% of the light that passes through it.

This whole system is called a geometric or reflective waveguide. The hard part of it, evidently, is the glass-making itself: They stack up layers of coated glass, cut them with a diamond wire saw on the diagonal, and grind them very precisely.

When the first video of these specs leaked, Karl Guttag noted that the waveguide structure looked like the one that Lumus has been making. Then, sure enough, German optics giant Schott announced the day before the Meta Display that they were the “first company capable of handling geometric reflective waveguide manufacturing in production volumes,” along with their partner Lumus. So it’s almost certain that the Display glasses are using Schott + Lumus waveguides (to be clear, Lumus also makes LCoS projectors, but that’s not what we’re seeing here: the LCoS panel in this case is an Omnivision OP03010, very similar to the OP03011 that Omnivision announced in 2023).

This specialty glass cutting sets the Meta Display glasses apart from other AR glasses we’ve seen. Other AR glasses use a system of gratings that bend and split light, instead of the system of mirrors we see inside the Meta Display glasses. 

That old system is called a “diffractive” waveguide, as opposed to the “geometric” waveguide we’re seeing in the Meta Display. The difference accounts for a common problem with other AR glasses: When you split light, it doesn’t just bend in the direction you want. This results in eye glow, the way that other AR glasses will flash abstract light shapes at your dinner guests. When you’re wearing glasses with that old style of waveguide, you may also see little rainbow artifacts when the gratings catch light from overhead. 

Meta’s specialty glass solves both these problems by using tiny mirrors, which reflect light instead of splitting it. Someone sitting across from you won’t see any evidence of the screen in your glasses. And you won’t see any artifacts. The geometric waveguide is a very clean, very effective solution. The only downside is it’s an expensive piece of glass. Being this close to the bleeding edge means it’s possible that each of these glasses are being sold at a loss.

We’re not counting on seeing waveguide replacement options if your fancy glass cracks or the lenses glued to either side of it get scratched. Glued to either side of the waveguide is a set of push/pull lenses, one of which has Transitions auto-darkening capability baked into it. Transitions lenses tend to lose their effectiveness (get slower to change and less effective at darkening) over time. So even if your battery holds out, these will be less useful sunglasses in a few years. 

All this to say: Don’t expect your local optician to be able to replace a lens in these for you.

Beyond the Glass

The hinges fare slightly better, but they’re still buried under glued panels and minuscule T3 screws. Nothing about this build invites tinkering. 

Peel back the arms and you’ll find more cutting-edge tech. The right side holds the Snapdragon AR1 chipset, paired with 32 GB of flash storage and 2 GB of LPDDR4X RAM. The left arm carries the battery, microphones, and open-ear speakers. The speakers are soldered in, but we were able to make reasonably quick work of them with our iFixit Fixhub Portable Soldering Station. Those speakers sound great considering how tiny they are and the fact that they’re not actually in your ears, but they’re soldered in, not clipped, so any failure means major surgery (or a funeral).

Every component is a testament to how far Meta’s miniaturization has come—and how far repairability still has to go.

So Where Do We Go From Here?

We don’t expect bleeding-edge hardware to be a repair dream from day one. Optical waveguides and sub-millimeter chipsets don’t leave much room for screws and connectors. But we’ve seen that slim and stylish doesn’t have to mean sealed and disposable. Just look at the iPhone Air: it’s thinner and lighter than ever, yet surprisingly repairable.

The Meta Ray-Ban Display glasses prove that wearable AR is no longer science fiction. Now we need manufacturers to prove that repairable wearables aren’t either. Replaceable batteries, modular arms, and swappable lenses aren’t impossible; they’re just not priorities yet.

Until they are, we’ll keep tearing down the future and reminding the world that the best technology isn’t just powerful or portable, it’s fixable.