Multiplex Holographic Optical Element for Expanded Eye Box
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Solution Overview
Problem
Conventional image display devices using holographic optical elements have a limited eye box due to the requirement for precise alignment of the viewer's eyes with a small focal point, restricting the viewing range and causing discomfort.
Innovation Solution
An image display device comprising multiple light sources, a spatial light modulator, and a multiplex holographic optical element that focuses beams on distinct focal points, allowing for identical images to be displayed across a broader range by using interference patterns and a processor to control the light sources and modulator, ensuring synchronization and pupil location detection for optimal image presentation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a holographic optical element is used as a combiner to focus light on a focal point, then image viewing is enabled, but the eye box (viewing range) is greatly reduced
Solution Approach 1:
The patent divides the single focal point into multiple focal points (first focal point and second focal point) by creating separate interference patterns in the holographic optical element. This segmentation allows the eye box to be distributed across multiple focal regions, effectively enlarging the total viewing range while maintaining reliable image viewing capability at each focal point
Solution Approach 2:
The patent extends the viewing range by adding a temporal dimension through sequential activation of multiple light sources. The first light source activates the first interference pattern for one eye, then the second light source activates the second interference pattern for the other eye, creating a multi-dimensional eye box that appears enlarged to the user
2Manufacturing precision
If eyes must be correctly located on a focal point to view a correct image, then image quality is maintained, but the viewing range is restricted
Solution Approach 1:
The patent creates different local qualities within the holographic optical element by forming distinct interference patterns at different locations. Each interference pattern is optimized for its specific focal point, allowing high image quality at each localized region while collectively providing an expanded viewing range across multiple regions
Solution Approach 2:
The patent introduces dynamic control through the processor that sequentially activates different light sources based on detected pupil locations. This dynamic switching maintains optimal image quality for each eye by activating the appropriate light source and interference pattern according to the real-time position of the user's pupils
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 solution expands the eye box by enabling identical images to be viewed across multiple focal points, enhancing the viewing range and user comfort by adjusting light sources and modulation based on pupil location, thereby improving the usability of AR glasses and similar devices.
Implementation Method 1
The holographic optical element may comprise a first interference pattern based on the first beam of light and a second interference pattern based on the second beam of light
Implementation Method 2
a multiplex holographic optical element that focuses beams on distinct focal points, allowing for identical images to be displayed across a broader range by using interference patterns
Data Source
AI summary
Provided is an image display device including a first light source configured to emit a first beam of light, a second light source configured to emit a second beam of light, a spatial light modulator configured to modulate the first beam of light and the second beam of light, a holographic optical element configured to focus, on a first focal point, the first beam of light emitted from the first light source and modulated by the spatial light modulator, and to focus, on a second focal point, the second beam of light emitted from the second light source and modulated by the spatial light modulator and a processor configured to control the first and the second light sources and the spatial light modulator.