Free-Form Beam Splitter Architecture for Compact AR Virtual Images
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Solution Overview
Problem
Existing augmented reality (AR) display systems suffer from optical aberrations and wavelength dispersion due to the use of refractive optical elements, leading to bulky and costly designs, particularly in wearable devices like AR glasses.
Innovation Solution
The use of free-form curved beam-splitting elements separated by free space, combined with a field corrector lens, reduces optical aberrations and wavelength dispersion, allowing for more compact and lightweight AR displays by minimizing light propagation through refractive materials.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If refractive optical elements are used in AR display systems, then light can be effectively redirected to form images, but optical aberrations and wavelength dispersion occur, leading to bulky and costly designs
Solution Approach 1:
The patent replaces refractive optical elements (lenses) with reflective optical elements (beam splitters with curved surfaces). This substitution eliminates the optical aberrations and wavelength dispersion inherent in refractive systems while maintaining the ability to redirect light and form images. The reflective beam splitters achieve the same light redirection function without the harmful side effects of refraction, thereby reducing optical system complexity and cost.
Solution Approach 2:
The patent employs beam splitters with curved surfaces (spherical, aspherical, or freeform curvature) instead of flat surfaces. These curved reflective surfaces enable effective light redirection and image formation while correcting optical aberrations. The curvature allows the beam splitters to focus and redirect light rays similarly to lenses but without the chromatic dispersion and other aberrations associated with refractive materials.
2Reliability
If multiple optical elements are used to redirect light in wearable AR devices, then the desired field of view and image quality can be achieved, but the device size and weight increase
Solution Approach 1:
The patent combines multiple optical functions into a single beam splitter component. The beam splitter simultaneously performs light redirection, image formation, and optical aberration correction that would traditionally require separate lenses and optical elements. This merging of functions reduces the number of discrete components, thereby reducing overall device weight and complexity while maintaining wearable form factor.
3Reliability
If traditional optical elements are used in AR displays, then light can be redirected to form virtual images, but the optical path length and system volume increase
Solution Approach 1:
The curved surfaces of the beam splitters enable compact optical folding paths. The spherical, aspherical, or freeform curvature allows light to be redirected through shorter, more efficient paths within the device housing. This reduces the overall optical path length and system volume compared to traditional lens-based systems that require longer focal lengths and larger separation distances between elements.
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 results in more attractive and cost-effective AR displays with reduced size and weight, enhancing the design form factor and user experience.
Implementation Method 1
both beam-splitting elements are arranged to redirect light emitted from the light source toward a user to form a virtual image
Implementation Method 2
the field corrector lens is arranged in front of the light source and redirects the light emitted from the light source toward the second beamsplitter
Data Source
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AI summary
A virtual image display system includes: a light source for projecting an image; a first beamsplitter including a first free-form curved surface; and a second beamsplitter including a second free-form curved surface facing the first free-form surface of the first beamsplitter, in which the first free-form curved surface is separated from the second-free form curved surface of the second beamsplitter by free space, and in which the first beamsplitter and the second beamsplitter are arranged to redirect light emitted from the light source toward a user to form a virtual image.