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 device comprises an optical waveguide including a volume of optically transparent material having a first longitudinal surface positioned opposite a second longitudinal surface across a width of the volume, an in-coupler, a liquid crystal out-coupler, and a controller to modulate a refractive index of the liquid crystal out-coupler. Light is in-coupled into the waveguide and is propagated along a length of the waveguide by total internal reflection between the longitudinal surfaces before being out-coupled by the liquid crystal out-coupler on a path that is dependent on the modulated refractive index of the liquid crystal out-coupler. In this way, light signals can be steered to create an image and/or to move an exit pupil of an image. WHUDs that employ such optical waveguides are also described.
1 . A method of operating a wearable heads-up display (WHUD) comprising a support structure that in use is worn on the head of a user, a projector with at least one light source, an optical waveguide including a volume of optically transparent material having a first longitudinal surface opposite a second longitudinal surface across a width of the volume of optically transparent material, an in-coupler, a liquid crystal out-coupler, and a controller communicatively coupled to the liquid crystal out-coupler, the method comprising:
generating a first set of light signals by the at least one light source of the projector;
in-coupling the second set of light signals into the volume of optically transparent material by the in-coupler;
propagating the second set of light signals along a length of the volume of optically transparent material by total internal reflection between the first longitudinal surface and the second longitudinal surface;
modulating a refractive index of the liquid crystal out-coupler to a second refractive index by the controller;
out-coupling the second set of light signals by the liquid crystal out-coupler, wherein the second set of light signals are output on a path that is dependent on the refractive index of the liquid crystal out-coupler.
2 . The method of claim 1 further comprising:
generating a second set of light signals by the at least one light source of the projector;
in-coupling the second set of light signals into the volume of optically transparent material by the in-coupler;
propagating the second set of light signals along a length of the volume of optically transparent material by total internal reflection between the first longitudinal surface and the second longitudinal surface;
modulating a refractive index of the liquid crystal out-coupler to a second refractive index by the controller;
out-coupling the second set of light signals by the liquid crystal out-coupler, wherein the second set of light signals are output on a path that is dependent on the refractive index of the liquid crystal out-coupler.