Holographic Optical Elements with Integrated Incoupler and Outcoupler
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Solution Overview
Problem
Existing optical systems face challenges in aligning multiple optical components, such as incouplers and outcouplers, which demand fine spatial tolerances and are difficult to assemble and align effectively, especially in holographic optical elements.
Innovation Solution
A method of recording multiple holograms in a contiguous holographic recording medium, where a first hologram directs light into a light guide and a second hologram directs it out, with the option of a third hologram splitting the beam, and affixing the medium to the light guide, potentially with an anti-reflective coating, to simplify alignment and reduce optical cross-talk.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If multiple separate optical components (incouplers and outcouplers) are used in holographic optical elements, then the light manipulation functionality is achieved, but the alignment complexity and assembly difficulty increase significantly due to fine spatial tolerance requirements
Solution Approach 1:
The patent combines multiple separate optical components (incoupler and outcoupler) into a single integrated holographic optical element. The incoupler and outcoupler are recorded as overlapping holograms within the same photopolymer medium, eliminating the need for separate physical components and their associated alignment procedures. This merging reduces assembly complexity while maintaining the required light manipulation functionality.
2Manufacturing precision
If multiple separate optical components are assembled, then the required optical functions are achieved, but the manufacturing precision requirements become extremely stringent due to fine spatial tolerances
Solution Approach 1:
The incoupler and outcoupler holograms are recorded simultaneously or sequentially within the same photopolymer medium during manufacturing. This integrated recording process eliminates the need for post-manufacturing alignment and assembly of separate components, significantly reducing the manufacturing precision requirements while maintaining the necessary optical performance.
Solution Approach 2:
The holographic patterns for both incoupler and outcoupler are pre-recorded into the photopolymer medium during the manufacturing process itself, before any assembly steps. This preliminary action ensures that the spatial relationships between optical components are established with high precision during the recording process, eliminating the need for subsequent alignment operations.
3Loss of energy
If separate optical components are used, then functional flexibility is maintained, but optical cross-talk between components increases and reduces system efficiency
Solution Approach 1:
By recording the incoupler and outcoupler as overlapping holograms within the same photopolymer medium, the patent creates a unified optical structure where the refractive index modulations are spatially integrated. This integration reduces optical cross-talk between the incoupler and outcoupler functions, as the light propagation paths are more precisely controlled within the single medium, thereby reducing energy loss.
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 simplifies the alignment process by integrating holograms within a single medium, reducing the need for precise spatial alignment of separate components and minimizing optical cross-talk, thereby enhancing the efficiency and accuracy of light manipulation in optical systems.
Implementation Method 1
Holograms may be made by creating patterns of variations in the refractive index of an optical medium. Refractive index may also be referred to as 'the index of refraction'. Making holograms by creating the variations in the refractive index may also be described as writing or recording the hologram in the medium.
Implementation Method 2
Holograms may be made by creating patterns of variations in the refractive index of an optical medium. Refractive index may also be referred to as 'the index of refraction'.
Data Source
AI summary
There are provided holographic optical elements (HOEs) and methods of making the same. An example of such methods includes recording a first hologram in a contiguous holographic recording medium of the HOE. The first hologram may receive a beam of light and direct at least a portion of the beam into a light guide to form an incoupled beam. The method also includes recording a second hologram in the contiguous holographic recording medium. The second hologram may receive at least a portion of the incoupled beam and direct the portion of the incoupled beam out of the light guide to form an outcoupled beam. In addition, the method includes affixing the holographic recording medium to the light guide.