Eyepieces for use in wearable display systems
An example a head-mounted display device includes a light projector and an eyepiece. The eyepiece is arranged to receive light from the light projector and direct the light to a user during use of the wearable display system. The eyepiece includes a waveguide having an edge positioned to receive light from the display light source module and couple the light into the waveguide. The waveguide includes a first surface and a second surface opposite the first surface. The waveguide includes several different regions, each having different grating structures configured to diffract light according to different sets of grating vectors.
1 . An apparatus comprising:
an eyepiece comprising a waveguide positioned to receive light from a light projector and couple the light into the waveguide, the waveguide comprising a first surface and a second surface opposite the first surface, and defining a first region, a second region, and a third region,
wherein in the second region of the waveguide, the second surface defines a plurality of first grating structures configured to diffract light according to a first diffraction pattern to expand a spatial distribution of the light,
wherein in the third region of the waveguide, the second surface defines a plurality of second grating structures configured to diffract light according to a second diffraction pattern different from the first diffraction pattern to out-couple at least a portion of the light from the waveguide,
wherein the second region increases in width as it extends in a direction away from the first region and defines a concave shape that partially encloses the third region, and
the third region increases in width as it extends in the direction away from the first region and decreases in width towards a periphery of the optical elements.
2 . The apparatus of claim 1 , wherein the first region, the second region, and the third region are in optical communication with one another.
3 . The apparatus of claim 1 , wherein the plurality of first grating structures defines a periodic one-dimensional grating, and
wherein the plurality of second grating structures defines a periodic two-dimensional grating.
4 . The apparatus of claim 1 , wherein a diffraction efficiency of the plurality of second grating structures at a first end of the third region is different from a diffraction efficiency of the plurality of second grating structures at a second end of the second third region opposite the first end of the third region.
5 . The apparatus of claim 1 , wherein the plurality of first grating structures is configured to diffract light according to a first set of one or more grating vectors, and
wherein the plurality of second grating structures is configured to diffract light in the third region of the waveguide according to a second set of one or more grating vectors different from the first set of one or more grating vectors.
6 . The apparatus of claim 1 , wherein the first surface is an optically smooth surface.
7 . The apparatus of claim 1 , wherein the first surface is a substantially planar surface.
8 . A head-mounted display comprising the apparatus of claim 1 .
9 . The apparatus of claim 1 , wherein the first region is configured to in-couple light into the eyepiece.
10 . The apparatus of claim 1 , wherein the second region defines a protrusion at an interface of the first region and the second region.
11 . The apparatus of claim 10 , wherein the protrusion is defined, at its periphery, by a planar edge forming an obtuse angle with adjacent edge of the second region.
12 . A method comprising:
forming a waveguide having a first surface and a second surface opposite the first surface and defining a first region, a second region, and a third region, wherein forming the waveguide comprises:
defining a plurality of first grating structures in the second region on the second surface, the plurality of first grating structures being configured to diffract light according to a first diffraction pattern to expand a spatial distribution of the light; and
defining a plurality of second grating structures in the third region on the second surface, the plurality of second grating structures being configured to diffract light according to a second diffraction pattern different from the first diffraction pattern to out-couple at least a portion of the light from the waveguide,
wherein the second region increases in width as it extends in a direction away from the first region and defines a concave shape that partially encloses the third region, and
the third region increases in width as it extends in the direction away from the first region and decreases in width towards a periphery of the optical elements.
13 . The method of claim 12 , wherein defining the plurality of first grating structures comprises defining a periodic one-dimensional grating.
14 . The method of claim 13 , wherein defining the plurality of second grating structures comprises defining a periodic two-dimensional grating.
15 . The method of claim 12 , further comprising configuring the first surface as an optically smooth surface.
16 . The method of claim 12 , further comprising configuring the first surface as a substantially planar surface.
17 . The method of claim 12 , further comprising producing a heat-mounted display using the waveguide.
18 . A method comprising:
obtaining a waveguide comprising a first surface and a second surface opposite the first surface and defining a first region, a second region, and a third region,
wherein in the second region of the waveguide, the second surface defines a plurality of first grating structures configured to diffract light according to a first diffraction pattern, and
wherein in the third region of the waveguide, the second surface defines a plurality of second grating structures configured to diffract light according to a second diffraction pattern different from the first diffraction pattern;
directing light into the first region of the waveguide;
expanding, using the second region of the waveguide, a spatial distribution of the light;
transmitting at least some of the light from the second region to the third region of the waveguide; and
out-coupling, along the third region, at least some of the light from the waveguide,
wherein the second region increases in width as it extends in a direction away from the first region and defines a concave shape that partially encloses the third region, and
the third region increases in width as it extends in the direction away from the first region and decreases in width towards a periphery of the optical elements.
19 . The method of claim 18 , wherein directing light into the first second region of the waveguide comprises directing the light from a light projector into the first second region of the waveguide.
20 . The method of claim 18 , wherein the light represents one or more images.
21 . The method of claim 18 , further comprising outputting at least some of the light from the third region of the waveguide towards an eye of a user.
22 . The method of claim 21 , wherein the user is wearing a head-mounted display device comprising the waveguide.
23 . The method of claim 18 , wherein expanding the spatial distribution of the light using the second region of the waveguide comprises:
expanding, in a first direction, the spatial distribution of the light within the first second region of the waveguide.
24 . The method of claim 23 , further comprising propagating at least some of the light within the third region of the waveguide, wherein propagating at least some of the light within the third region of the waveguide comprises expanding, in a second direction, the spatial distribution of the light within the third region of the waveguide.
25 . The method of claim 24 , wherein the first direction is orthogonal to the second direction.