Today the US Patent & Trademark Office published a patent application from Apple that relates to optical systems and, more particularly, to optical systems for displays in a mixed reality Head-Mounted Display Device (HMD) or future smart glasses. The system most notably includes the use of An Angle-Selective Transmission Filter (ASTF) that is used to create a three-dimensional reconstruction of holographic recordings.

Apple's patent application/invention covers an electronic device such as a head-mounted device may have one or more near-eye displays that produce images for a user. The head-mounted device may be a pair of virtual reality glasses or may be an augmented reality headset that 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 an emissive display panel having an array of pixels that emit light. The emitted light may propagate along an optical path extending from the emissive display panel towards an eye box. A waveguide may be interposed on the optical path. An input coupler may couple the light into the waveguide. An output coupler may couple the light out of the waveguide and towards the eye box. Imaging optics may direct the light towards the input coupler. A prism may direct the light from the emissive display panel towards the imaging optics. The prism may combine light from multiple emissive display panels.

An angle-selective transmission filter (ASTF) may be interposed on the optical path at one or more locations. For example, the ASTF may be interposed between one or more of the emissive display panels and the prism, between the prism and the imaging optics, between the imaging optics and the input coupler, or within the waveguide.

The ASTF may filter the emitted light as a function of angle to produce filtered light. For example, the ASTF may transmit a first portion of the emitted light (e.g., as the filtered light) along the optical path and may re-direct a second portion of the emitted light outside of the optical path. The first portion of the emitted light may span a first set of incident angles relatively close to a normal axis of the ASTF. The second portion of the emitted light may be high angle light that spans a second set of incident angles farther from the normal axis than the first portion of the emitted light.

Apple's patent FIG. 1 below is a diagram of an illustrative system having a display. System #10 may include input-output circuitry such as input-output devices #12. Input-output devices may be used to allow data to be received by the system from external equipment (e.g., a tethered computer, a portable device such as a handheld device or laptop computer, or other electrical equipment) and to allow a user to provide the head-mounted device with user input.

Input-output devices may also be used to gather information on the environment in which the system and HMD is operating. Output components may allow the system and device to provide a user with output and may be used to communicate with external electrical equipment.

Input-output devices may include sensors and other components 18 (e.g., image sensors for gathering images of real-world object that are digitally merged with virtual objects on a display in the HMD.

In one suitable arrangement components (#18) may include gaze tracking sensors that gather gaze image data from a user's eye at eye box (#24) to track the direction of the user's gaze in real time. As an example, the gaze tracking sensors may include infrared or other light emitters that emit infrared light or other light towards the eye box and image sensors that sense the infrared or other light reflected off of the user's eye (e.g., where the sensed light identifies the gaze direction of the user's eye).

Apple's patent FIG. 2 below is a top view of an illustrative optical system for a display having a waveguide with an input coupler and an output coupler.

If desired, the waveguide (#26) may also include one or more layers of holographic recording media (sometimes referred to as holographic media, grating media, or diffraction grating media) on which one or more diffractive gratings are recorded.

A holographic recording may be stored as an optical interference pattern (e.g., alternating regions of different indices of refraction) within a photosensitive optical material such as the holographic media. The optical interference pattern may create a holographic phase grating that, when illuminated with a given light source, diffracts light to create a three-dimensional reconstruction of the holographic recording.

Apple notes that the optical path #40 in FIG. 3 above may also include an angle-selective transmission filter such as angle-selective transmission filter (ASTF) #44. The ASTF may be optically interposed within optical path between emissive display panel #42 and eye box #24 (FIG. 2).

For more technical details, that engineers will appreciate, check out Apple's patent application number 20210247610. Considering that this is a patent application, the timing of such a product to market is unknown at this time.

Below are a few of the inventors listed on the Patent Application:

Vikrant Bhakta, PhD: Research Manager.

Guolin Peng, PhD: Sr. Display Incubation Engineer

Johnny (Hyungryul) Choi: Engineering Manager (was an MIT Research Assistant)