Rectangular Waveguide Optical Aperture Multiplier
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Solution Overview
Problem
Existing optical aperture multipliers face challenges in efficiently expanding two-dimensional optical apertures, particularly in achieving uniform illumination and reducing manufacturing complexities, such as strict tolerances for parallelism and perpendicularity of optical waveguide faces.
Innovation Solution
The design incorporates a rectangular optical waveguide with partially reflective surfaces and a thin slab-type optical waveguide, where the optical coupling is achieved through a configuration that trims the input collimated image to ensure uniform illumination and uses a partially reflective surface associated with the waveguide's face for coupling, simplifying fabrication and reducing costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If internal partially reflective surfaces are used within the rectangular waveguide for coupling light, then light coupling efficiency is improved, but manufacturing complexity and cost increase due to strict tolerance requirements for parallelism and perpendicularity of waveguide faces
Solution Approach 1:
The invention extracts the partially reflective surface from the internal structure of the rectangular waveguide and relocates it to the interface between the two waveguides. This is achieved by providing a partially reflective surface on the lower face of the rectangular waveguide that forms the optical coupling interface with the thin slab-type waveguide. By moving the reflective surface to the interface, the patent eliminates the need for internal reflective surfaces and their associated strict manufacturing tolerances for parallelism and perpendicularity, thereby reducing manufacturing complexity while maintaining light coupling efficiency.
2Area of stationary object
If multiple internal reflective surfaces are deployed within the waveguide for aperture expansion, then aperture multiplication capability is improved, but device complexity increases
Solution Approach 1:
The invention merges the functions of multiple internal reflective surfaces into a single interface-based partially reflective surface. Instead of deploying multiple internal reflective surfaces within the rectangular waveguide to achieve aperture expansion, the patent combines the coupling function at the interface between the rectangular waveguide and the thin slab-type waveguide. This single interface structure accomplishes both light coupling and aperture expansion, thereby reducing device complexity while maintaining aperture multiplication capability.
3Reliability
If strict alignment tolerances are enforced for waveguide faces to ensure proper optical coupling, then optical performance is improved, but manufacturing time and cost increase
Solution Approach 1:
The invention changes the optical parameters at the waveguide interface by introducing a partially reflective surface with specific reflectivity characteristics. This parameter change allows the system to achieve proper optical coupling without requiring strict mechanical alignment tolerances for waveguide face parallelism and perpendicularity. The partially reflective surface compensates for alignment variations, enabling faster manufacturing while maintaining optical performance.
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 approach enhances aperture expansion, ensures uniform illumination across the expanded aperture, and simplifies the manufacturing process by reducing the need for precise alignment of optical components, thereby improving light efficiency and reducing manufacturing costs.
Implementation Method 1
The rectangular waveguide has two pairs of parallel faces (that form a rectangular cross-section) and is configured to guide light by four-fold internal reflection at the two pairs of parallel faces
Implementation Method 2
a proportion of intensity of the image is reflected at the first set of internal surfaces so as to be coupled into the second waveguide
Implementation Method 3
The second waveguide has a pair of parallel faces and is configured to guide the coupled-in light by internal reflection at the pair of parallel faces, and to couple the guided light outwards toward a viewer
Implementation Method 4
the optical coupling is achieved through a configuration that trims the input collimated image to ensure uniform illumination
Data Source
AI summary
An optical device includes a first waveguide, having parallel first and second faces and parallel third and fourth faces forming a rectangular cross-section, that guides light by four-fold internal reflection and is associated with a coupling-out configuration that couples light out of the first waveguide into a second waveguide. The first or second face is subdivided into first and second regions having different optical characteristics. The optical device also includes a coupling-in configuration having a surface that transmits light into the first waveguide. The surface is deployed in association with a portion of the third or fourth face adjoining the second region such that an edge associated with the surface trims an input collimated image in a first dimension, and a boundary between the first and second regions trims the input collimated image in a second dimension to produce a trimmed collimated image that advances by four-fold internal reflection.