Compound Light-Guide Optical Elements With Embedded Coupling Reflectors
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Solution Overview
Problem
Existing methods for manufacturing compound light-guide optical elements (LOEs) with embedded coupling-in reflectors are limited in their ability to efficiently expand optical apertures in two dimensions, leading to suboptimal image projection and display capabilities.
Innovation Solution
A method involving the fabrication of compound LOEs by bonding optical blocks with non-parallel internal reflective surfaces, cutting and polishing to form LOEs with embedded coupling-in reflectors, and optionally incorporating inert blocks to enhance structural integrity and optical properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If compound LOEs are fabricated using conventional methods, then the basic light guide function is achieved, but the two-dimensional aperture expansion capability is insufficient
Solution Approach 1:
The compound LOE is divided into multiple regions (first region with first facets, second region with second facets, third region with third facets) having different facet orientations. Each region is formed by bonding separate optical blocks with specific facet configurations, allowing independent optimization of each region's contribution to two-dimensional aperture expansion while maintaining manufacturability through modular assembly
Solution Approach 2:
The patent employs composite optical structures by bonding together optical blocks with different facet orientations and properties. The composite nature of the compound LOE, combining multiple optical regions with different reflective surface orientations, enables enhanced two-dimensional aperture expansion capability that cannot be achieved with a single homogeneous structure
2Adaptability or versatility
If multiple optical blocks with non-parallel internal surfaces are bonded together, then two-dimensional aperture expansion is achieved, but the manufacturing process becomes more complex
Solution Approach 1:
Different regions of the compound LOE are assigned different local qualities through varying facet orientations. The first region has facets at a first angle, the second region has facets at a second angle, and the third region has facets at a third angle. This local differentiation enables each region to contribute specifically to two-dimensional aperture expansion in different directions, while the bonding process integrates these differentiated regions into a cohesive optical structure
3Manufacturing precision
If precise alignment of internal reflective surfaces is ensured, then optical performance is improved, but the bonding process becomes more difficult
Solution Approach 1:
The optical blocks are pre-formed with their respective facet structures and alignments before bonding. The first optical block is formed with first facets at a first angle, the second optical block with second facets at a second angle, and the third optical block with third facets at a third angle. This preliminary formation of precise geometric features enables subsequent bonding processes to achieve accurate alignment of the compound LOE regions without requiring complex real-time alignment procedures
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
The method enables effective two-dimensional aperture expansion, improving image projection and display capabilities by ensuring precise alignment and reflectivity of internal surfaces, resulting in enhanced optical performance.
Implementation Method 1
facilitating the propagation of light corresponding to a collimated image by internal reflection at major surfaces, and includes a set of mutually-parallel, internal, partially-reflective surfaces (or 'facets'), which redirect the collimated image light while achieving expansion of the optical aperture
Implementation Method 2
bonding together the first optical block and the stack such that one of the faces of the first pair of faces is joined to one of the faces of the second pair of faces
Data Source
AI summary
A stack has first and second faces and multiple LOEs that each has two parallel major surfaces and a first plurality of parallel internal facets oblique to the major surfaces. A first block has third and fourth faces and a second plurality of parallel internal facets. The first block and the stack are bonded such that the second face joins the third face and the first and second facets are non-parallel, forming a second block. The second block is cut at a plane passing through the first face, forming a first structure having an interfacing surface. A third block has fifth and sixth faces and a plurality of parallel internal reflectors. The third block and the first structure are bonded such that fifth face joins the interfacing surface and the internal reflectors are non-parallel to all the facets, forming a second structure. Compound LOEs are sliced-out from the second structure.