EYEPIECES FOR AUGMENTED REALITY DISPLAY SYSTEM
An eyepiece waveguide for an augmented reality display system. The eyepiece waveguide can include an optically transmissive substrate with an input coupling grating (ICG) region. The ICG region can receive a beam of light and couple the beam into the substrate in a guided propagation mode. The eyepiece waveguide can also include a combined pupil expander-extractor (CPE) grating region that receives the beam of light from the ICG region and alters the propagation direction of the beam with a first interaction and out-couples the beam with a second interaction. The diffractive features of the CPE grating region can be arranged in rows and columns of alternating higher and lower quadrilateral surfaces or the diffractive features can comprise diamond shaped raised ridges. The eyepiece waveguide can also include one or more recycler grating regions.
1 . An eyepiece waveguide for an augmented reality display system, the eyepiece waveguide comprising:
an optically transmissive substrate having a first surface and a second surface;
an input coupling grating (ICG) region formed on or in one of the surfaces of the substrate, the ICG region being configured to receive an input beam of light and to couple the input beam into the substrate as a guided beam;
a first combined pupil expander-extractor (CPE) grating region formed on or in the first surface of the substrate, the first CPE grating region being positioned to receive the guided beam from the ICG region and to create a first plurality of diffracted beams at a plurality of distributed locations, and to out-couple a first plurality of output beams; and
a second CPE grating region formed on or in the second surface of the substrate, the second CPE grating region being positioned to receive the guided beam from the ICG region and to create a second plurality of diffracted beams at a plurality of distributed locations, and to out-couple a second plurality of output beams.
2 . The eyepiece waveguide of claim 1 , wherein the first CPE grating region is configured to out-couple the second plurality of diffracted beams, and the second CPE grating region is configured to out-couple the first plurality of diffracted beams.
3 . The eyepiece waveguide of claim 2 , wherein the first and second plurality of diffracted beams alternately interact with the first and second CPE grating regions.
4 . The eyepiece waveguide of claim 1 , wherein the first CPE grating region and the second CPE grating region both comprise a plurality of periodically repeating diffractive lines, and wherein the diffractive lines of the first CPE grating region are oriented at an angle of substantially 60° with respect to the diffractive lines of the second CPE grating region.
5 . The eyepiece waveguide of claim 4 , wherein the diffractive lines of the first and second CPE grating regions have the same period.
6 . The eyepiece waveguide of claim 4 , wherein the ICG region comprises a plurality of periodically repeating diffractive lines, and wherein the diffractive lines of the ICG region are oriented at an angle of substantially 60° with respect to the diffractive lines of the first CPE grating region and the diffractive lines of the second CPE grating region.
7 . The eyepiece waveguide of claim 6 , wherein the diffractive lines of the ICG region, the first CPE grating region, and the second CPE grating region have the same period.
8 . The eyepiece waveguide of claim 1 , further comprising:
a first recycler grating region adjacent to the first CPE grating region, the first recycler grating region being located and configured to receive some of the first plurality of diffracted beams from the first CPE grating region and to re-direct them back toward the first CPE region; and
a second recycler grating region adjacent to the second CPE grating region, the second recycler grating region being located and configured to receive some of the second plurality of diffracted beams from the second CPE grating region and to re-direct them back toward the second CPE region.
9 . The eyepiece waveguide of claim 8 , wherein the first and second recycler grating regions comprise a plurality of periodically repeating diffractive lines, and wherein the diffractive lines of the first and second recycler grating regions are oriented at an angle of substantially 30° with respect to the diffractive lines of the first CPE grating region and the diffractive lines of the second CPE grating region.
10 . The eyepiece waveguide of claim 1 , wherein the first and second CPE grating regions overlap by at least 90%.
11 . The eyepiece waveguide of claim 1 , wherein the first and second CPE grating regions are the same size.
12 . The eyepiece waveguide of claim 11 , wherein the first and second CPE grating regions are aligned with one another.
13 . The eyepiece waveguide of claim 1 , wherein the first CPE grating region is configured to create the first plurality of diffracted beams by diffracting portions of the power of the guided beam from the ICG region in at least two directions.
14 . The eyepiece waveguide of claim 13 , wherein one of the two directions corresponds to a zero order diffracted beam.
15 . The eyepiece waveguide of claim 1 , wherein the second CPE grating region is configured to create the second plurality of diffracted beams by diffracting portions of the power of the guided beam from the ICG region in at least two directions.
16 . The eyepiece waveguide of claim 15 , wherein one of the two directions corresponds to a zero order diffracted beam.
17 . The eyepiece waveguide of claim 1 , wherein the first plurality of diffracted beams propagate in a first direction, and wherein the second plurality of diffracted beams propagate in a second direction at an angle of substantially 60° with respect to the first direction.
18 . The eyepiece waveguide of claim 1 , wherein the ICG region is further configured to receive the beam of light that is collimated and has a diameter of 5 mm or less.
19 . The eyepiece waveguide of claim 1 , wherein the optically transmissive substrate is planar.
20 . An augmented reality display system comprising an eyepiece that includes the eyepiece waveguide of claim 1 .