Apple Engineers Advance Near-Eye Displays for Smartglasses and HMD using Holographic Optical Elements and more
Today the US Patent & Trademark Office published a patent application from Apple that relates to optical systems that include holographic optical elements and, more particularly, to optical systems for near-eye displays found in augmented or VR glasses (or headset).
Optical Systems for Displays
Apple notes that it could be challenging to design near-eye displays for glasses or a headset. If care is not taken, some of the field of view produced by a near-eye display may not be viewable from a single eye position. This is one the areas that Apple's invention is to overcome.
Apple's invention covers AR and/or VR glasses or Head-Mounted (headset) with one or more near-eye displays that produce images for a user. The glasses or headset allows a viewer to view both computer-generated images and real-world objects in the viewer's surrounding environment.
The near-eye display may include a display unit that directs light and an optical system that redirects the light from the display unit towards a user's eyes.
The optical system may include an input coupler and an output coupler formed on a waveguide. The input coupler may redirect light from the display unit so that it propagates in the waveguide towards the output coupler.
The output coupler may redirect the light from the input coupler so that it exits the waveguide towards the user's eyes. The input and output couplers may be formed from holographic optical elements such as thin holograms, volume holograms, or surface relief gratings.
A light-redirecting element may be used to redirect or redistribute light that would otherwise be outside of the user's field of view towards the user's eyes. The light-redirecting element may be interposed between the display unit and the input coupler, may be interposed between the input coupler and the output coupler, or may be integrated with the output coupler.
In arrangements where the light-redirecting element is interposed between the display unit and the input coupler, the light-redirecting element may include a secondary input coupler and a secondary output coupler on a second waveguide.
Apple's patent FIG. 1 below is illustrative system having a device with one or more near-eye display systems. The device could be a pair of glasses or a full Mixed Reality Headset.
In configurations in which system #10 is a pair of virtual reality glasses, near-eye display #20 may obscure the user's view of the user's surrounding environment.
In configurations in which system is a pair of augmented reality glasses, the display may be transparent and/or may be provided with optical mixers such as half-silvered mirrors to allow the viewer (#16) to simultaneously view images on the display and external objects such as object #18 in the surrounding environment.
Apple's patent FIG. 2A above is a top view of an illustrative near-eye display system having an optical system including an input coupler and an output coupler at least partially embedded in a waveguide substrate.
As shown in FIG. 2A, the display could be LCD, OLED or a projector display (e.g., a projector based on an array of micromirrors),
Input coupler #30 and output coupler #32 may be based on reflective and refractive optics or may be based on holographic (e.g., diffractive) optics. In arrangements where both couplers are formed from reflective and refractive optics, the couplers may include one or more reflectors (e.g., an array of micromirrors or other reflectors). Holographic Elements are listed six times in Apple's patent claims showing the importance of this feature to this invention.
In arrangements where both couplers are based on holographic optics, the couplers may include volume holographic media such as photopolymers, gelatin such as dichromated gelatin, silver halides, holographic polymer dispersed liquid crystal, or other suitable volume holographic media.
A holographic recording may be stored as an optical interference pattern (e.g., alternating regions of different indices of refraction) within the photosensitive optical material. The optical interference pattern may create a holographic grating that, when illuminated with a given light source, diffracts light to create a three-dimensional reconstruction of the holographic recording.
Apple's patent application 20190377181 that was published today by the U.S. Patent Office was filed back in Q3 2018. Considering that this is a patent application, the timing of such a product to market is unknown at this time.
Some of Apple's Inventors
Graham Myhre, PhD: Senior Engineering Manager of Display Exploration. Myhre previously worked for Lytro where he designed next-gen Light Field optics and micro-optics for the ILLUM Lytro camera.
Eric Hansotte: Sr. Display Exploration Engineer
Johnny (Hyungryul) Choi: Engineering Manager; Investigate new display and optical technologies for future Apple products.
Paul Gelsinger: Display Exploration Engineer: 14 years experience in optics R&D