Holographic Optical Element Layout for Uniform HUD Eye Box Brightness
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Solution Overview
Problem
Augmented image light emitted from a holographic optical element used in a head-up display is not effectively focused on a user's eye box area, and the brightness of the augmented image is not uniform throughout.
Innovation Solution
The holographic optical element is formed by combining multiple optical elements with the same pitch but different inclination angles, allowing for high brightness and uniform emission of augmented image light to the user's eye box area.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a conventional holographic optical element uses interference patterns with constant maximum diffraction efficiency angles, then light with high brightness is emitted in a certain direction, but most of the light is emitted to areas other than the user's eye box area, lowering the brightness of the augmented image
Solution Approach 1:
The holographic optical element is divided into multiple regions, each with interference patterns having different inclination angles. This segmentation allows different parts of the element to direct light to different areas, ensuring that light is distributed uniformly across the user's eye box area rather than concentrated in a single direction.
Solution Approach 2:
Different regions of the holographic optical element are assigned different local properties (different inclination angles of interference patterns) to optimize light emission for each region. This ensures that each part of the element contributes to illuminating the eye box area uniformly, with each region's characteristics tailored to its specific function in the overall light distribution.
2Illumination intensity
If a conventional holographic optical element emits light with high brightness to a specific direction, then light containing information on a specific part of the augmented image has high brightness, but the augmented image viewed by the user has different brightness for each part
Solution Approach 1:
The interference patterns in different regions of the holographic optical element are designed with asymmetric inclination angles rather than uniform angles. This asymmetric design allows each region to emit light at different angles, ensuring that light from different parts of the augmented image is distributed uniformly across the eye box area, achieving brightness uniformity across the entire image.
Solution Approach 2:
The solution introduces variation in the inclination angle dimension of interference patterns across different regions. By adding this dimensional variation (different angles in different regions), the system transforms the light emission from a concentrated directional pattern into a distributed uniform pattern across the eye box area, achieving brightness uniformity.
3Adaptability or versatility
If light is emitted with high brightness in a certain direction by a conventional holographic optical element, then the augmented image can be seen clearly in that direction, but the brightness of the augmented image is lowered when viewed from other directions
Solution Approach 1:
The holographic optical element is designed with multiple interference pattern regions, each functioning to direct light to different areas of the eye box. This multi-functional design allows the element to provide high brightness augmented images across a wide range of viewing angles, as each region contributes to illuminating different directional areas uniformly.
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 enables the user to see an augmented image with high and uniform brightness by focusing and uniformly emitting light containing information on each part of the image to the eye box area.
Implementation Method 1
A holographic optical element is an optical element produced by recording an interference pattern on a photosensitive material through interference between an object wave, which is light reflected and diffracted from an object, and a reference wave which is another wave coherent with the light
Implementation Method 2
the photosensitive material having the interference pattern recorded thereon reproduces augmented image information using diffraction instead of reflection or refraction
Implementation Method 3
this photosensitive material is also classified as a type of diffractive optical element... reproduces augmented image information using diffraction
Data Source
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AI summary
The present disclosure relates to a holographic optical element, a method for producing the same, and an apparatus for producing the same, and more particularly, to a holographic optical element capable of enhancing the brightness of an augmented image, a method for producing the same, and an apparatus for producing the same.