Multi-substrate Holographic Optical System for Compact Near-to-Eye Displays
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Solution Overview
Problem
Existing substrate-guided hologram technologies are limited in their ability to create larger near-to-eye displays with a wider field of view and more compact form factors, as they lack flexibility in substrate geometries and refractive index differences, which restricts the design of optical devices.
Innovation Solution
The use of a holographic lens positioned at an angle to a holographic grating with a mirror placed diagonally between them, along with substrates of different refractive indices, allows for a collimated near-to-eye display with a virtual image seen at infinite or closer distance, enabling more flexible design options for guided angles, thicknesses, and display geometries.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a single substrate is used for substrate-guided holograms, then the structure is simple, but the flexibility in substrate geometries and refractive index differences is limited
Solution Approach 1:
The patent divides the optical system into multiple separate substrates (first substrate with holographic lens, second substrate with holographic grating) that can be independently selected with different refractive indices and geometries. This segmentation allows optimization of each substrate's properties to achieve desired optical performance while maintaining design flexibility.
Solution Approach 2:
The patent employs composite material structures by combining different substrate materials with distinct refractive indices (e.g., first substrate with higher refractive index, second substrate with lower refractive index) to create an optical system with enhanced adaptability and controlled light propagation characteristics.
2Adaptability or versatility
If substrates with different refractive indices are used, then flexibility in display geometries and guided angles is improved, but manufacturing complexity increases
Solution Approach 1:
The patent introduces air gaps or optical coupling media as intermediaries between the first and second substrates to facilitate precise alignment and controlled optical coupling. This intermediary approach enables flexible geometry design while managing the manufacturing complexity of integrating multiple substrates with different refractive indices.
3Area of stationary object
If holographic lens and grating are on the same substrate, then alignment is easier, but the field of view and display size are limited
Solution Approach 1:
The patent transitions from a planar single-substrate configuration to a three-dimensional multi-substrate arrangement with spatial separation. The holographic lens and grating are positioned on different substrates at specific distances and angles, enabling expanded field of view and display size while maintaining optical alignment through controlled spatial geometry.
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 configuration enables the construction of wider range near-to-eye displays with improved field of view and thinner, more compact form factors, providing greater flexibility in design and reducing weight and volume, while maintaining image quality and user privacy.
Implementation Method 1
The light beam is confined within the substrate by total internal reflection and propagates through the substrate to holographic material
Implementation Method 2
it diffracts at a shallow angle to travel by total internal reflection through the substrate
Implementation Method 3
bounces off the mirror into the second substrate
Implementation Method 4
A microdisplay is spaced from the lens at the lens' focal distance or closer to create a collimated type of Near to Eye (NTE) display with the virtual image seen at infinite or closer at a predetermined distance
Implementation Method 5
The light beam is confined within the substrate by total internal reflection and propagates through the substrate to holographic material where it overlaps with another guided or non-guided beam, creating an interference pattern
Data Source
AI summary
The present invention is a Substrate guided hologram that allows a wider range of optical devices based on SGHs with improved parameters such as larger NTE displays with a wider field of view, thinner substrates and more compact form factors. The Substrate-Guided Hologram of the subject invention includes a holographic lens which is positioned at an angle to and spaced from a holographic grating, with a mirror located at a diagonal to each of the lens and the grating.