Dichroic Combiner Integrated Lightguide for Compact AR Displays
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Solution Overview
Problem
Existing augmented reality displays using micro-LED arrays are limited to generating monochromatic images, requiring three arrays of different colors to produce a color image, which results in bulky combining optics, particularly problematic for near-eye displays that require compact components.
Innovation Solution
The use of dichroic combiners integrated with a lightguide, along with optical relays between rectangular lightguides, allows for the efficient combination of light from multiple monochrome image projectors, enabling compact and effective color image generation in augmented reality displays.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If three micro-LED arrays of different colors are used to generate color images, then color image quality is improved, but the combining optics become bulky
Solution Approach 1:
The patent merges the lightguides with the dichroic combiners into a single integrated component. The lightguide is formed within the body of the dichroic combiner, eliminating the need for separate combining optics. This integration allows multiple monochrome image projectors to be combined into a single compact unit that can be integrated with the lightguide, directly resolving the contradiction between color image generation capability and optical system volume.
Solution Approach 2:
The patent implements nesting by placing the lightguide inside or within the structure of the dichroic combiner. The lightguide is formed within the body of the dichroic combiner, creating a nested configuration where one optical element is contained within another. This nesting approach significantly reduces the overall volume of the combining optics while maintaining the functionality of both color combination and light guidance.
2Adaptability or versatility
If three micro-LED arrays of different colors are used to generate color images, then color image quality is improved, but the display becomes bulky
Solution Approach 1:
The patent merges the lightguides with the dichroic combiners into a single integrated component. The lightguide is formed within the body of the dichroic combiner, eliminating the need for separate combining optics. This integration allows multiple monochrome image projectors to be combined into a single compact unit that can be integrated with the lightguide, directly resolving the contradiction between color image generation capability and optical system volume.
Solution Approach 2:
The patent utilizes the third dimension (depth/thickness) by forming the lightguide within the body of the dichroic combiner rather than arranging components in a planar layout. This three-dimensional integration allows the optical system to maintain all necessary functions (color combination, light guidance, and image projection) while occupying minimal space, thereby improving display compactness.
3Adaptability or versatility
If separate combining optics are used to combine three colors, then color combination is achieved, but device complexity increases
Solution Approach 1:
The patent merges the lightguides with the dichroic combiners into a single integrated component. The lightguide is formed within the body of the dichroic combiner, eliminating the need for separate combining optics. This integration allows multiple monochrome image projectors to be combined into a single compact unit that can be integrated with the lightguide, directly resolving the contradiction between color image generation capability and optical system volume.
Solution Approach 2:
The integrated lightguide-dichroic combiner structure performs multiple functions simultaneously: it guides light from multiple monochrome image projectors, combines different colors through the dichroic properties, and transmits the combined color image. This multi-functionality reduces the number of separate components needed, thereby reducing device complexity while maintaining color combination capability.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This solution enables the creation of compact and efficient augmented reality displays capable of producing full-color images, addressing the bulkiness issue associated with traditional combining optics and enhancing the portability and usability of near-eye displays.
Implementation Method 1
a dichroic reflector embedded in the lightguide, oriented perpendicular to the major surfaces and bisecting an angle between the first in-plane direction and the second in-plane direction, the dichroic reflector being transparent to the first color and reflective to the second color so as to redirect the light of the second color so as to combine with the light of the first color
Implementation Method 2
a lightguide having a pair of mutually-parallel major surfaces supporting propagation of light within the lightguide by internal reflection at the major surfaces
Data Source
AI summary
A display includes a lightguide (10, 110) with mutually-parallel major surfaces and at least two image projectors (2a, 2b, 2c) outputting collimated light of at least first and second colors, respectively. In one embodiment, the two image projectors introduce the collimated light so as to propagate within the lightguide along the same in-plane direction. Interference of one of the coupling-in arrangements with internal reflection of the other color is avoided by providing a dichroic reflector (9a1, 9b1, 9a2, 9b2, 9a3) coplanar with a major surface of the lightguide. Alternatively, or additionally, the two colors may be introduced so as to propagate in two non-parallel directions, and are combined by a dichroic reflector (12a, 12b) embedded within the lightguide. Also disclosed is a display with an optical relay (66a, 66b) for transferring images between two non-parallel lightguides (110a and 110b, 10).