Glasses work

How do smart glasses work?

Smart glasses are the next big thing in wearable smart technology. They offer the ability to bring the technology found in our smartphones directly to our eyes and ears.

In 2013, Google launched the first smart glasses. The Google Glass Explorer ended up being a business failure, but since then several companies have launched their own version of smart glasses, and the field is getting more and more exciting month by month.

So how do smart glasses work? Are they as complicated as they look? Keep reading to find out.

What are smart glasses?

Photo of a person wearing smart glasses

Smart glasses are portable computer glasses that can have various functions. Some overlay information in the field of view like an augmented reality (AR) overlay. Some may offer the ability to answer calls and listen to music, but offer no visual output. Others can simply change the darkness of the lenses depending on the lighting.

Basically, smart glasses aim to deliver the wireless functionality of smartphones and similar devices right to your face or head. The smart glasses can be controlled by touch or completely hands-free. They can allow you to make calls or reply to messages, take photos and videos from your point of view, listen to music, interact with applications, use GPS navigation or ‘display an AR overlay.

Smart glasses also have significant potential capabilities in various industries including logistics, healthcare, and construction.

What parts are smart glasses made of?

Photo of augmented reality glasses

For smart glasses to provide functionality similar to smartphones and other devices, they must be easily controlled, have multiple sensors, and produce visual and audio outputs.

Here are the functional parts of smart glasses and how they work.

Audio capability

Smart glasses can be used to take calls or watch videos. These functions, as well as many similar functions, require audio output to be possible. Instead of using speakers, some smart glasses transfer sound to the cochlea (ear bone) through bone conduction rather than through the air. This involves sending vibrations from the spectacle frame to the cochlea via the skull, bypassing the eardrum.

A microphone

Most smart glasses have a small microphone that can record your voice and surrounding sounds. This is required for smart glasses that have voice control, call functionality or video recording with audio.

Computer processor

Like any computer, smart glasses require a central processing unit (CPU). This is usually held in one of the arms of the frames, and therefore should be small. Usually the processor is the same or similar to a smartphone processor, like the Qualcomm Snapdragon XR1.

The human-machine interface (HMI)

Eye tracking

This is how a person controls their smart glasses. The human-machine interface has to apply to glasses, which means that typical commands like a touchscreen or a computer mouse are not suitable.

Instead, smart glasses can be controlled by one or more of the following:

  • Buttons.

  • Speech recognition.

  • Gesture recognition.

  • Eye tracking.

  • Remote control (via smartphone).


Like normal glasses, many smart glasses can be equipped with different types of lenses. These can be corrective lenses (for poor eyesight), blue light filtering glasses for computers, or “smart” lenses, which darken depending on the surrounding light conditions.


Many smart glasses need a camera. Google Glass Explorer has been criticized for constantly logging in people around, posing a significant legal and ethical issue for all smart glasses. The camera is used for shooting and analysis by the glasses so that an AR overlay is possible.

Some newer smart glasses do not include a camera. These usually only provide audio capabilities.

Display: curved mirrors and waveguides

The display has been the hardest part of smart eyeglass development so far. Let’s take a look at some of the technologies behind AR screens in smart glasses.

There are two main types of screens for smart glasses. These are the curved mirror display and waveguide displays.

A curved mirror works by projecting an image onto a curved mirror that reflects light directly into the wearer’s eye. The problem with the curved mirror approach is that the device has to be larger and the image is less sharp.

Waveguides, on the other hand, are a collection of newer technologies (many of which are still in development). These include:

  • Diffractive waveguide.

  • Holographic waveguide.

  • Reflective waveguide.

  • Virtual retinal display.

A waveguide works by “bending” the light projected in front of your eyes to display a visual field (including 3D augmented reality objects). The light is sent through a piece of almost completely translucent plastic or glass designed to reflect light along the material. Light bounces along the waveguide to the area in front of the eye, then projects an image directly onto the eye.

One problem with waveguides is the limited FOV they provide. For example, the HoloLens waveguide provides a 30-50 degree field of view, while normal human vision is around 220 degrees. There are some claims of FOV waveguides above 100 degrees, but none have yet passed the proof of concept stage.

The main problem is that increasing the FOV means increasing the size of the waveguides and the bulk of the glasses.

Another challenge is resolution. Smart glasses need to have a high-resolution display to be realistic or to distinguish details (like text). The challenge is that, unlike a screen that you can view directly, smart glasses have a complex optical system that can degrade the resolution.

Add in other complications like color accuracy and real-world distortions, and it’s incredibly difficult to create a high-quality display.

What do current smart glasses look like?

There are dozens of smart glasses commercially available or in development. None are perfect, and many are expensive, but technology is advancing rapidly. Here are two examples of smart glasses currently available.

Amazon Echo Frames

The Amazon Echo smart glasses are not AR, so they do not provide any visual display. Instead, they come with four directional speakers and a microphone so you can listen to music, control your Alexa Home, or make calls.

Improved Vuzix blade

These are proper AR glasses, offering a full waveguide display on the right eye. With an 8-megapixel camera and voice commands, the glasses allow users to take photos, play a selection of games, watch streaming services, and more.

The future of augmented reality

Smart glasses have come a long way since Google’s first attempt. Today there are dozens of manufacturers and the technology is evolving at an incredible rate. With new waveguide displays in development delivering better-than-ever resolution, field of view and clarity, the future of AR is exciting.

Commercially available AR glasses are still expensive and leave a little to be desired, but who knows what the next few years will bring.

Image Credit: Dan Leveille / Website

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