AR is a hard field full of hard problems. At Kura, we believe in coming up with innovative solutions to these problems.
Field of View
While we usually only focus on the center of our field of vision, humans have a huge field of view. In addition to being important for providing context for e.g. design visualization, being able to project a wide field of view is essential for comfort – a too-narrow field of view can cause tunnel vision and confusion.
Our headsets feature a diagonal field of view of over 130 degrees. For comparison, the current class leader (the Microsoft Hololens) has a field of view of just 52 degrees. On Kura 1, this is done with clever optics and micro-OLED technology. Kura 2 uses a cutting-edge micro-LED display engine in conjunction with MEMS, diffractive, and light guide technologies to achieve an incredibly wide (150+ degree) field of view in a compact package.
Resolution
All the field of view in the world is useless if everything in the image is blurry. On conventional displays, high resolution is nice, but…it’s honestly not that important – films looked about as good in the 2K days as they do in the current 4K/6K era (the entire Star Wars prequel trilogy was shot in 2K!), and the de-facto standard for computer displays has been 1080p (2MP) for almost a decade now.
In contrast, resolution critically affects the usability of an AR (or VR) headset – at around 50 pixels per degree, text becomes comfortably readable. For a 120 degree field of view, this translates into about 6000 pixels in each direction – a spec that cannot be achieved with currently-available area display technology.
Different designs take different approaches to dealing with this issue. VR headsets typically just give up – as the technology targets entertainment applications where fast frame rates are important and graphics are complex, trading text readability for a lower resolution, easier-to-render image is usually worth it.
A number of other AR designs on the market use laser beam scanning technology to achieve the requisite resolution. In this design, a point light source is scanned with a two-axis micromirror system several million times per second to create an area display. LBS solves the resolution problem by decoupling the system resolution from the display resolution; unfortunately, it introduces a whole slew of other issues:
- As a single light source is scanned over the entire display area of several million points, the light source needs to be millions of times brighter than the display, making outdoor usability a challenge at best and an impossibility at worst.
- The single flying spot places substantial load on the mechanical scanning system – the spot rate can be hundreds of millions of positions per second for a wide-field, high-resolution system with sufficient frame rate.
- The rapidly moving spot, in conjunction with other optical tricks used in the pipeline (DOE’s, waveguides) can result in unpleasant and nauseating side effects.