MEMS Projection Optics With Layered Light Folding for Compact XR Wearables
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Solution Overview
Problem
Existing image projection systems for extended reality technologies, particularly those used in wearable headgear like eyeglasses, are bulky and costly due to the use of curved glass, which complicates manufacturing and increases size, making them uncomfortable for users.
Innovation Solution
A compact image projection system using flat glass structures with a vertically stacked arrangement, eliminating curved glass, and incorporating a MEMS mirror and optical elements to steer light beams for image rendering, reducing the lateral footprint to less than 0.3 cm³.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If curved glass is used in image projection systems, then image quality can be maintained, but the system becomes bulky and costly with complicated manufacturing
Solution Approach 1:
The patent transitions from using curved glass surfaces to a vertically stacked layered structure, changing the spatial arrangement from lateral curvature to vertical stacking. This dimensional reorganization allows the system to maintain optical functionality while reducing lateral footprint to less than 0.3 cm³ and simplifying manufacturing processes.
Solution Approach 2:
The system is divided into multiple functional layers including first and second glass layers, first and second semiconductor crystal layers, and an internal cavity. Each layer performs a specific optical function, allowing the complex optical path to be achieved through simple flat layered structures rather than a single curved glass element.
2Ease of manufacture
If curved glass is used in image projection systems, then optical path can be controlled, but manufacturing cost and complexity increase
Solution Approach 1:
The patent replaces complex curved glass structures with a vertically stacked layered configuration, shifting the optical control mechanism from lateral geometric complexity to vertical layering. This reduces manufacturing cost by using simple flat layers that are easier to produce and assemble.
Solution Approach 2:
The layered structure serves multiple functions simultaneously: the first glass layer and first semiconductor layer define the internal cavity, the second semiconductor layer with slanted surfaces provides optical redirection, and the second glass layer completes the structural enclosure. This multi-functionality reduces the need for separate specialized components.
3Ease of operation
If curved glass is used in wearable headgear, then image projection is achieved, but user comfort decreases due to bulk
Solution Approach 1:
By organizing the optical system in a vertical stack rather than using lateral curvature, the patent reduces the lateral footprint to less than 0.3 cm³. This compact vertical arrangement makes the device suitable for wearable headgear where minimal lateral bulk is critical for user comfort.
Solution Approach 2:
The system nests multiple functional layers within a compact volume, with the internal cavity containing the MEMS mirror suspended from the first semiconductor layer. This nested arrangement maximizes functional density while minimizing the overall lateral footprint.
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 results in a more compact and cost-effective image projection system that enhances user comfort by minimizing bulk, while maintaining image quality through efficient light steering using MEMS mirrors and optical elements.
Implementation Method 1
the first internal slanted surface is configured to receive the light beams from the light source and direct the light beams toward the second internal slanted surface
Implementation Method 2
the second internal slanted surface is configured to receive the light beams from the first internal slanted surface and direct the light beams toward the MEMS mirror
Implementation Method 3
the MEMS mirror is configured to steer the light beams to render the image
Data Source
AI summary
An image projection system includes a layer stack defining an internal cavity, and a microelectromechanical system (MEMS) mirror arranged in the internal cavity. The layer stack includes a first glass layer, a first semiconductor crystal layer, a second semiconductor crystal layer, and a second glass layer, the internal surfaces of which define the internal cavity. The second semiconductor crystal layer includes a first internal slanted surface and a second internal slanted surface that define a portion of the internal cavity. The first internal slanted surface is configured to receive light beams from a light source and direct the light beams toward the second internal slanted surface. The second internal slanted surface is configured to receive the light beams from the first internal slanted surface and direct the light beams toward the MEMS mirror. The MEMS mirror is configured to steer the light beams to render an image.