Transparent waveguide display providing upper and lower fields of view having a specific light output aperture configuration

An apparatus for displaying an image comprising:

• an input image node for providing image modulated light;
• a first beam expander comprising a first optical substrate comprising at least one waveguide layer configured to propagate the modulated light in a first direction, wherein the at least one waveguide layer of the first optical substrate comprises at least one grating lamina configured to extract the modulated light from the first substrate along the first direction;
• a second beam expander comprising a second optical substrate comprising at least one waveguide layer configured to propagate the modulated light in a second direction, wherein the at least one waveguide layer of the second optical substrate comprises at least one grating lamina configured to extract the modulated light from the second substrate along the second direction;
• a first optical waveguide, separate from the first and second optical substrates, comprising at least one waveguide layer configured to propagate the modulated light, wherein the at least one waveguide layer of the first optical waveguide comprises at least one grating lamina, the first optical waveguide having a first end nearest the input image node and a second end furthest from the input image node, a diffraction efficiency of the first optical waveguide varying from the first end of the first optical waveguide to the second end of the first optical waveguide to be highest at the second end of the first optical waveguide such that light coupled out of the first optical waveguide provides uniform illumination in any field of view direction based on the diffraction efficiency of the first optical waveguide varying from the first end of the first optical waveguide to the second end of the first optical waveguide, a light output aperture of the first optical waveguide being larger than a light output aperture of the first optical substrate and a light output aperture of the second optical substrate,
• wherein the light coupled out of the first and second optical waveguides provides uniform illumination in any field of view direction
• a second optical waveguide, separate from the first and second optical substrates, comprising at least one waveguide layer configured to propagate the modulated light, wherein the at least one waveguide layer of the second optical waveguide comprises at least one grating lamina, the second optical waveguide having a first end nearest the input image node and a second end furthest from the input image node, a diffraction efficiency of the second optical waveguide varying from the first end of the second optical waveguide to the second end of the second optical waveguide to be highest at the second end of the second optical waveguide such that light coupled out of the second optical waveguide provides uniform illumination in any field of view direction based on the diffraction efficiency of the second optical waveguide varying from the first end of the second optical waveguide to the second end of the second optical waveguide, a light output aperture of the second optical waveguide being larger than a light output aperture of the first optical substrate and the second optical substrate,
• wherein
• the at least one grating lamina of the first optical substrate is configured to couple the modulated light into the first optical substrate and then into the first optical waveguide;
• the at least one grating lamina of the second optical substrate is configured to couple the modulated light passing through the first optical substrate into the second optical substrate and then into the second optical waveguide;
• the at least one grating lamina of at least one of the first and second optical substrates has a k-vector that varies along the respective direction of light propagation,
• the at least one grating of the first optical waveguide configured to couple the modulated light from the first optical substrate out of the first optical waveguide, and
• the at least one grating of the second optical waveguide configured to couple the modulated light from the second optical substrate out of the second optical waveguide, and to pass the modulated light from the first optical waveguide,
• wherein the first optical waveguide is disposed directly between the first optical substrate and the second optical substrate, and the second optical substrate is disposed directly between the first optical waveguide and the second optical waveguide.