Apple is working on light waveguide and holographic transmission technologies to help reduce the size and weight of future augmented reality (AR) or virtual reality (VR) helmets, according to newly exposed patent documents, according tomedia. Currently the most common VR helmets rely on displays placed close to the user’s eyes, plus multiple lenses. Although this has led to relatively low production costs for helmets, it also poses many problems. Apple said in its patent filing that these lens-based settings may have limitations and that “some of the field of view generated by the near-eye display may not be visible from a single-eye position.”
Figure 1: VR helmet Oculus Quest uses the most common display-lens combination
Another problem is the display itself, as its position away from the face forces other components and enclosures to be placed further away from the user’s face, which can put more pressure on the face. If the display can be placed closer and use fewer or lighter components, the helmet may be more comfortable to wear.
In the patent, entitled “Optical Systems for Displays,” Apple proposes using a waveguide system to transfer light from the optical system to the user’s eye. Waveguide replaces the display and is used to project images into the user’s eyes through redirected light.
Figure 2: The patent describes how the light emitted by the display unit passes through the waveguide and reflects onto the user’s eyes
To aid the waveguide system, Apple proposes using an input and output coupler, where the input coupler redirects light from the display unit to the waveguide, and the output coupler pushes the light in the direction of the eye. These images can be formed by holographic optics, including thin holograms, volume holograms, and surface embossed grating.
Apple’s design also helps redirect or reassign “light out of sight” to the user’s eye by using a light redirect element located between the display unit and the input coupler.
The system can use two waveguides (one per eye), or two input and output couplers, plus a waveguide with a holographic element to redirect light into the correct eye. In this case, the light redirection element can also use the interference mode that is not flat with the output coupler, which helps prevent light prepared for one eye from being seen by chance by the other.
Rumours have been circulating for a long time that Apple is developing some form of AR or VR helmet or smart glasses. Many patent documents show that the company is keen to develop the concept.
In an Apple patent application in September called “Display Devices,” Apple referred to a system of waveguides and holographic elements in which AR helmets use “reflective holographic combinations” to combine digital elements with real-world views.
Apple seems particularly interested in waveguide technology, with engineers and key personnel visiting the booths of AR waveguide suppliers, including DigiLens, Lumus, Vuzix and WaveOptics, at the 2019 CES show. Apple also acquired Akoni Holographics, the maker of AR helmet lenses, in 2018 and VRvana, AR helmet maker, in 2017.
Rumours of smart glasses, known as “Apple Glasses,” suggest Apple is working on an AR device called the T288, which runs the company’s rOS operating system with 8K displays. It is rumored that a separate processing unit will overlay the virtual image on real-world objects that exist in the user’s vision.