Hologram waveguiding

A method of holographic projection, the method comprising:

• forming a first holographic wavefront by illuminating a first hologram of a picture;
• forming a second wavefront;
• receiving the first holographic wavefront and second wavefront at an input of a waveguide;
• waveguiding the first holographic wavefront and second wavefront between a pair of opposing reflective surfaces of the waveguide by internal reflection;
• outputting a plurality of replicas of the first holographic wavefront and second wavefront at a partially transmissive first surface of the pair of opposing reflective surfaces, the first surface thereby forming an output port;
• receiving the first holographic wavefront at an eye-box for a viewer, wherein a first holographic image of the picture is formed for a viewer at the eye-box, the first holographic image appearing in a region between the first hologram and eye-box, wherein the second wavefront forms a light pattern in the region for a viewer at the eye-box;
• and
• detecting at a light detector a light return of the light pattern if an object is present in the region, wherein a field of view of the light detector corresponds with a size of the light pattern, and wherein the light pattern illuminates a detection area substantially corresponding to the region of the first holographic image.

Tangible, non-transitory, computer readable media comprising program instructions, wherein the program instructions, when executed by a computing system, cause the computing system to perform a method of holographic projection comprising:

• forming a first holographic wavefront by illuminating a first hologram of a picture;
• forming a second wavefront;
• receiving the first holographic wavefront and second wavefront at an input of a waveguide;
• waveguiding the first holographic wavefront and second wavefront between a pair of opposing reflective surfaces of the waveguide by internal reflection;
• outputting a plurality of replicas of the first holographic wavefront and second wavefront at a partially transmissive first surface of the pair of opposing reflective surfaces, the first surface thereby forming an output port;
• receiving the first holographic wavefront at an eye-box for a viewer, wherein a first holographic image of the picture is formed for a viewer at the eye-box, the first holographic image appearing in a region between the first hologram and eye-box, wherein the second wavefront forms a light pattern in the region for a viewer at the eye-box;
• and
• detecting at a light detector a light return of the light pattern if an object is present in the region, wherein a field of view of the light detector corresponds with a size of the light pattern, and wherein the light pattern illuminates a detection area substantially corresponding to the region of the first holographic image.