SYSTEMS, DEVICES, AND METHODS FOR OPTICAL WAVEGUIDES
Systems, devices, and methods for optical waveguides that are well-suited for use in wearable heads-up displays (WHUDs) are described. An optical waveguide includes a volume of optically transparent material, a first holographic optical element (HOE) and a second holographic optical element, wherein the first HOE and the second HOE are carried by the volume of optically transparent material, and the first HOE is positioned across a width of the volume of optically transparent material from the second HOE. Light enters the optical waveguide and is propagated down a length of the waveguide by reflection between the first HOE and the second HOE. Propagation of the light within the optical waveguide does not require total internal reflection. The optical waveguide may include means to in-couple the light into the waveguide and means to out-couple the light from the waveguide. WHUDs that employ such optical waveguides are also described.
1 . A method of operating a wearable heads-up display comprising a support structure that in use is worn on the head of a user, a projector with at least one light source, and an optical waveguide including a volume of optically transparent material, a first HOE carried by the volume of optically transparent material, a second HOE carried by the volume of optically transparent material, an in-coupling region, and an out-coupling region, the method comprising:
generating light signals by the at least one light source;
receiving the light signals by the optical waveguide;
in-coupling the light signals into the optical waveguide by the in-coupling region;
propagating the light signals down a length of the volume of optically transparent material by reflection by and between the first HOE and the second HOE; and
outputting the light signals towards an eye of the user by the out-coupling region.
2 . The method of claim 1 wherein the projector further includes a controllable mirror, the method further comprising:
directing the light signals towards the optical waveguide by the controllable mirror.
3 . The method of claim 1 wherein the projector includes a processor and a non-transitory processor-readable medium that stores data and/or instructions, and wherein generating light signals by the at least one light source includes, in response to executing the data and/or instructions by the processor, modulating the light signals by the light source.
4 . The method of claim 1 wherein receiving the light signals by the optical waveguide includes transmitting the light signals through the first HOE or the second HOE.
5 . The method of claim 1 wherein the in-coupling region includes a portion of the second HOE and wherein in-coupling the light signals into the optical waveguide by the in-coupling region includes reflecting the light signals into the optical waveguide by the in-coupling region of the second HOE.
6 . The method of claim 1 wherein the in-coupling region includes a portion of the first HOE, and wherein in-coupling the light signals into the optical waveguide by the in-coupling region includes transmitting the light signals through the in-coupling region of the first HOE into the optical waveguide.
7 . The method of claim 1 wherein the in-coupling region includes a dedicated in-coupling element, and wherein in-coupling the light signals by the in-coupling region includes transmitting the light signals through the dedicated in-coupling element into the optical waveguide.
8 . The method of claim 1 wherein propagating the light signals along a length of the volume of optically transparent material by reflection by and between the first HOE and the second HOE includes propagating the light signals internally along the length of the volume of optically transparent material by reflection by and between the first Hoe and the second HOE.
9 . The method of claim 1 wherein outputting light signals towards an eye of the user by the out-coupling region includes transmitting the light signals through the first HOE or the second HOE towards the eye of the user.
10 . The method of claim 1 wherein the out-coupling region includes a portion of the second HOE and wherein outputting light signals by the out-coupling region towards an eye of the user includes reflecting the light signals by the out-coupling region of the second HOE towards the eye of the user.
11 . The method of claim 1 wherein the out-coupling region includes a portion of the first HOE, and wherein outputting light signals by the out-coupling region towards an eye of the user includes transmitting the light signals through the out-coupling region of the first HOE towards the eye of the user.
12 . The method of claim 1 wherein the out-coupling region includes a dedicated out-coupling element, and wherein outputting light signals towards an eye of the user by the out-coupling region includes transmitting the light signals through the dedicated out-coupling element towards the eye of the user.