Waveguide combiner with separate in-coupling and out-coupling plates
A waveguide-based see-through combiner for mixed-reality head mounted display (HMD) devices uses input and output couplers comprising holographic optical elements (HOEs) to respectively in-couple light for virtual images from a display engine to the waveguide combiner and out-couple the virtual images to an HMD user's eyes. The in-coupling and out-coupling HOEs are respectively disposed on separate plates that are optically coupled by a waveguide. The plates and waveguide may be fabricated (e.g., molded) from an optically transparent polymeric material. The utilization of separate plates enables optimization for placement and sizing of the out-coupling HOE in front of the user's eye to thereby increase eyebox size for the virtual images and improves quality of the see-through experience.
1. A head-mounted display (HMD) device wearable by a user and supporting a mixed-reality experience comprising a display of virtual images for objects in a virtual world and real-world images for objects in a real world, comprising:
a display engine generating an entrance pupil comprising one or more optical beams for the virtual images;
a see-through waveguide combiner configured to receive the virtual images from the display engine with the entrance pupil, the waveguide combiner configured to provide an exit pupil for the virtual images that is expanded in two directions relative to the entrance pupil generated by the display engine;
a see-through plate, disposed in the waveguide combiner, located in front of an eye of the user when the HMD is donned, through which the user views the real world, the see-through plate including an out-coupling holographic optical element (HOE), disposed in a front waveguide, configured for out-coupling virtual images to the eye of the user, the out-coupling HOE further configured for expanding the exit pupil in a first direction of the two directions;
a non-see-through plate, disposed in a temple of the HMD device outside a boundary of a visual field of the user when the HMD device is donned, the non-see-through plate including an in-coupling HOE, disposed in a side waveguide, configured for in-coupling the virtual images into the non-see-through plate, the non-see-through plate further including an intermediate HOE, disposed in a side waveguide, configured for expanding the exit pupil in a second direction of the two directions, wherein the first direction is orthogonal to the second direction; and
a connecting waveguide optically coupling the see through plate and non-see-through plate wherein the connecting waveguide is optically coupled along edges of respective waveguides in the see-through and the non-see-through plates to enable the virtual images in-coupled into the non-see-through plate to propagate in total internal reflection to the see-through plate in the waveguide combiner and be out-coupled by the out-coupling HOE to the eye of the user,
wherein the see-through plate and non-see-through plate are non-co-planar in the waveguide combiner.
2. The HMD device of claim 1 having an eyeglasses form factor having a pair of lenses coupled by a bridge and a pair of temples, wherein the see-through plate is disposed in a lens and the non-see-through plate is disposed in a temple of the pair of temples.
3. The HMD device of claim 1 in which sections of the connecting waveguide have a shape selected from one of straight, curved, or a combination of straight and curved.
4. The HMD device of claim 1 in which one or more of the HOEs comprise a reflective optical element, a diffractive optical element, or volume holographic grating.
5. The HMD device of claim 1 in which the see-through plate and the non-see-through plate are spatially separated in the waveguide combiner.
6. The HMD device of claim 1 in which one or more of the in-coupling HOE, intermediate HOE, and out-coupling HOE are fabricated from stacked layers of glass and one or more of the see-through plate, non-see-through plate, and waveguide are fabricated from injection-molded polymer.
7. The HMD device of claim 1 in which the see-through plate and non-see-through plate each comprise a stack of sub-plates, wherein each sub-plate propagates a unique color in an RGB (red, green, blue) color model.
8. The HMD device of claim 1 in which the see-through plate and non-see-through plate are each configured as a single layer plate for propagating polychromatic virtual image light.
9. The HMD device of claim 1 in which the in-coupling HOE comprises a prism.
10. The HMD device of claim 1 in which the out-coupling HOE is sized to fill the see-through portion of the waveguide combiner substantially in its entirety.