Apple is working on optical wave guides and holographic image transmission technologies to help mitigate future augmented reality (AR) or virtual reality (VR ) Helmet volume and weight. Figure 1: Oculus Quest VR headset uses the most common display + lens combination
The most common VR headsets today rely on a display placed close to the user’s eyes, plus multiple lenses. Although this results in relatively low production costs for helmets, it also poses many problems. Apple stated in its patent application document that these lens-based settings may have limitations, and “part of the field of view produced by the near-eye display may not be visible from the monocular position.”
Another problem is the display itself, because its wearing position away from the face forces other components and housings to be placed further away from the user’s face, which may put more stress on the face. If the display can be placed closer and fewer or lighter components are used, the helmet may be more comfortable to wear.
In the patent document entitled “Optical System for Display”, Apple proposes to use a wave guide system to transmit light from the optical system to the user’s eyes. The wave guide replaces the display and is used to project the image into the user’s eyes through redirected light.
Figure 2: The patent describes how the light emitted by the display unit passes through the wave guide and is reflected on the user’s eyes
To assist the wave guide system, Apple proposes using input and output couplets, where the input coupler redirects light from the display unit into the wave guide and the output coupler pushes the light in the direction of the eye. These generated images can be formed from holographic optical elements, including thin holograms, volume holograms, and surface relief gratings.
Apple’s design can also help redirect or redistribute “light outside the user’s field of view” to the user’s eyes by using a light redirection element located between the display unit and the input coupler.
The system can use two wave guides (one for each eye), or two input and output couplers, plus a wave guide with a holographic element to redirect light to the correct eye. In this case, the light redirecting element can also use an interference mode that is not parallel to the interference mode of the output coupler, which helps prevent light prepared for one eye from being accidentally seen by the other eye.
Rumors of Apple developing some form of AR or VR headset or smart glasses have been circulating for a long time. Many patent documents show that the company is keen to develop the concept.
In an Apple patent application entitled “Display Device” in September, Apple mentioned a system consisting of wave guides and holographic elements, in which AR headsets use a “reflective holographic combiner” to combine digital elements with real-world views .
Apple seems to be particularly interested in wave guide technology. Its engineers and key personnel visited the booth of AR wave guide suppliers at CES 2019. These companies include Digi Lens, Lumus, Vuzix, and WaveOptics. Apple also acquired AR helmet lens maker Akoni Holographics in 2018, and in 2017 acquired AR helmet startup Vrvana.
Rumors about the smart glasses called “Apple Glasses” suggest that Apple is committed to launching an AR device internally called “T288”, which runs the company’s rOS operating system and uses an 8K display. There are rumors that a separate processing unit will overlay a virtual image on a real-world object that exists in the user’s vision.