SCREEN CONFIGURATION FOR DISPLAY SYSTEM
An optical configuration for a display system includes a front screen, a first microlens array, and a second microlens array. The front screen has optical properties to absorb ambient light and let image light through. The first microlens array is coupled to receive the image light from a pixel array of an image generation layer. The second microlens array is disposed between the front screen and the first microlens array. The second microlens array is offset from the first microlens array by approximately a focal length of microlenses in the first microlens array. The second microlens array is coupled to direct the image light received from the first microlens array through front screen. Each of the microlenses in the first microlens array is axially aligned with a corresponding microlens in the second microlens array.
1 . An optical configuration for a display system comprising:
a front screen having optical properties to absorb ambient light, wherein the front screen includes an array of pinholes;
a first microlens array coupled to receive image light from a pixel array of an image generation layer; and
a second microlens array disposed between the front screen and the first microlens array, wherein the second microlens array is offset from the first microlens array by approximately a focal length of microlenses in the first microlens array, and wherein the second microlens array is coupled to direct the image light received from the first microlens array through the array of pinholes, each of the microlenses in the first microlens array axially aligned with a corresponding microlens in the second microlens array.
2 . The optical configuration of claim 1 further comprising an encapsulation material disposed between the first microlens array and the second microlens array.
3 . The optical configuration of claim 2 , wherein the encapsulation material has a different index of refraction than the first and second microlens array.
4 . The optical configuration of claim 1 , wherein the second microlens array includes a plurality of lens subsets, each lens subset including:
a center lens centered around a center pinhole in the array of pinholes; and
surrounding lenses offset from centers of corresponding pinholes by an offset distance, wherein the offset distance increases progressively as a distance from the center lens increases.
5 . The optical configuration of claim 4 , wherein the first microlens array has a homogeneous pitch between microlenses in the first microlens array, and wherein the second microlens array has the homogeneous pitch between microlenses in the second microlens array, and further wherein a spacing between pinholes in the array of pinholes increases as the offset distance increases.
6 . The optical configuration of claim 1 , wherein a configuration of the first and second microlens array has a numerical aperture of illumination that is at or below an acceptance angle of the configuration to prevent optical crosstalk between adjacent microlenses in the second microlens array.
7 . The optical configuration of claim 1 , wherein the second microlens array directs a chief ray of the image light normal to a plane of the front screen.
8 . The optical configuration of claim 1 , wherein the first microlens array and the second microlens array are integrated into a contiguous part of a same material.
9 . The optical configuration of claim 1 , wherein a first curvature of the microlenses in the first microlens array faces a same direction as a second curvature of microlenses in the second microlens array.
10 . The optical configuration of claim 1 , wherein a first curvature of the microlenses in the first microlens array faces an opposite direction of a second curvature of the microlenses in the second microlens array.
11 . The optical configuration of claim 1 further comprising:
an illumination layer having a plurality of light sources, wherein each of the light source is configured to emit a divergent projection beam having a well-defined angular extent; and
an image generation layer having a plurality of pixel arrays spaced apart from neighboring pixel arrays in the plurality of pixel arrays, wherein each pixel array is configured to receive the divergent projection beam from one of the light sources in the plurality of light sources and generate the image light that includes a projected sub-image.
12 . The optical configuration of claim 11 , wherein each of the light sources in the plurality of light sources is centered under one pixel array in the plurality of pixel arrays.
13 . The optical configuration of claim 12 , wherein the second microlens array includes a plurality of lens subsets, each lens subset including:
a center lens centered around a center pinhole in the array of pinholes, wherein the center lens is axially aligned with a center of one of the light sources.
14 . The optical configuration of claim 1 , wherein the second microlens array is offset from the first microlens array by between 1.0× and 1.2× a focal length of the microlenses in the first microlens array.
15 . A display apparatus comprising:
an illumination layer having a plurality of light sources, wherein each of the light sources is configured to emit a divergent projection beam having a well-defined angular extent;
an image generation layer having a plurality of pixel arrays spaced apart from neighboring pixel arrays in the plurality of pixel arrays, wherein each pixel array is configured to receive the divergent projection beam from one of the light sources in the plurality of light sources and generate image light including a projected sub-image;
a first microlens array coupled to receive the projected sub-images from the image generation layer;
a linear polarizer layer, wherein the projected sub-images combine to form a unified image;
a quarter-wave plate disposed between the first microlens array and the linear polarizer layer; and
a second microlens array disposed between the quarter-wave plate and the first microlens array, wherein the second microlens array is coupled to direct the image light received from the first microlens array to encounter the quarter-wave plate at an angle nominally normal to a plane of the quarter-wave plate, each of the microlenses in the first microlens array axially aligned with a corresponding microlens in the second microlens array.
16 . The display apparatus of claim 15 further comprising a polarization preserving diffuser configured to shape an angular distribution of the image light after the image light exits the second microlens array, wherein the polarization preserving diffuser includes a non-homogeneous microlens array.
17 . The display apparatus of claim 16 , wherein the polarization preserving diffuser is disposed between the second microlens array and the quarter-wave plate.
18 . The display apparatus of claim 15 further comprising an encapsulation material disposed between the first microlens array and the second microlens array.
19 . The display apparatus of claim 18 , wherein the encapsulation material has a different index of refraction than the first and second microlens array.
20 . The display apparatus of claim 15 , wherein a configuration of the first and second microlens array has a numerical aperture of illumination that is at or below an acceptance angle of the configuration to prevent optical crosstalk between adjacent microlenses in the second microlens array.