From Forbes: How do waveguides and combiners compare in building augmented reality displays? [originally appeared on Quora: the knowledge sharing network where compelling questions are answered by people with unique insights.]
Answer by Aaron Yip, game developer, on Quora:
See-through optics has a sort of inaccessible mysticism thanks to scifi (Iron Man, Star Trek, etc.) and dense hardware vocabulary. But it’s actually super easy to get started. So this will be an accessible, layman’s introduction to the topic.
Let’s begin with basics. We have these partially transparent displays that mix digital images with the real world. Light rays need to bounce off something to redirect into your eye. From the real world, we are already getting redirected rays. From the digital world, we need to create artificial light (e.g. from LEDs, OLEDs) and then redirect them. The optical device that combines this generated computer image with the real world is called a “combiner.” Essentially, a combiner works like a partial mirror that redirects the display light and selectively lets light in through from the real world. Pretty simple.
Like the question suggests, the optical hardware solutions can break down to two categories: conventional HMD optical combiners and emerging waveguide combiners. And hopefully obvious, both of these are very different, and have very different tradeoffs, from opaque virtual reality displays.
There is an extensive history of see-through displays since the late 1960s (I’ll add some good places to get more technical background at the end). Consequently there is a huge range of optical technologies, but it all boils down to basic tradeoffs between resolution, field of view, eye box, image quality, hardware weight/fit, aesthetic form factor, and other features. Ideally, everyone wants stylish, easy-to-use glasses with 200×100 degree FOV (like human eyes) and perfect image quality invented by Tony Stark from Iron Man.