Folded Optical Layout for Compact Head-Mounted Image Quality
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Solution Overview
Problem
Conventional optical lenses for head-mounted devices struggle to balance size reduction with high image quality, with Fresnel lenses compromising image quality while conventional lenses fail to minimize device size effectively.
Innovation Solution
An optical system comprising an aperture stop, reflective polarizer, partial reflector, quarter-wave plates, and multiple lens elements, including one with negative refractive power, is designed to fold light paths and reduce stray light, thereby minimizing device size while maintaining high image quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional optical lenses are used, then image quality is good, but device size cannot be effectively reduced
Solution Approach 1:
The optical system is divided into multiple lens elements (first optical lens element, second optical lens element, third optical lens element) with different refractive powers. Each lens element performs specific optical functions, allowing the system to achieve both compact size and high image quality through coordinated action of segmented components rather than relying on a single conventional lens.
Solution Approach 2:
The patent introduces a reflective polarizer and partial reflector that fold the light path in a multi-dimensional arrangement. By combining refractive and reflective optical elements in a three-dimensional configuration, the system achieves compact device size while maintaining adequate image quality through sophisticated light path management.
2Volume of moving object
If Fresnel lenses are used, then device size is reduced, but image quality becomes poor
Solution Approach 1:
The optical system uses a composite configuration combining multiple lens elements with different refractive properties and a reflective polarizer. This composite approach integrates the advantages of both refractive and reflective optical elements, achieving compact size through multi-element arrangement while maintaining high image quality through precise optical design and stray light reduction.
Solution Approach 2:
The reflective polarizer and partial reflector act as intermediary elements that control and direct light paths between the lens elements and the image sensor. These intermediary components enable the system to achieve compact size while maintaining image quality by mediating the optical interactions and reducing stray light effects.
3Manufacturing precision
If multiple lens elements are added to improve image quality, then device complexity increases
Solution Approach 1:
The patent merges multiple optical functions into a compact arrangement of lens elements and reflective components. By combining refraction and reflection in a unified optical path, the system achieves high image quality while controlling device complexity through integrated design rather than separate independent components.
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 optical system achieves a compact form factor with improved image quality by folding light paths and reducing stray light, enhancing user experience through reduced weight and size without sacrificing image clarity.
Implementation Method 1
a reflective polarizer located between the aperture stop and the image surface
Implementation Method 2
a reflective polarizer located between the aperture stop and the image surface
Implementation Method 3
a first quarter-wave plate located between the reflective polarizer and the partial reflector, a second quarter-wave plate located between the partial reflector and the image surface
Implementation Method 4
a first optical lens element located between the aperture stop and the image surface, a second optical lens element located between the first optical lens element and the image surface, a third optical lens element located between the second optical lens element and the image surface
Data Source
AI summary
An optical system includes an aperture stop, an image surface, a reflective polarizer, a partial reflector, first and second quarter-wave plates and first, second and third lens elements. The aperture stop and the image surface are respectively at a front side and a rear side of the optical system. The reflective polarizer is between the aperture stop and the image surface. The partial reflector is between the reflective polarizer and the image surface. The first quarter-wave plate is between the reflective polarizer and the partial reflector. The second quarter-wave plate is between the partial reflector and the image surface. The first lens element is between the aperture stop and the image surface. The second lens element is between the first lens element and the image surface. The third lens element has negative refractive power and is between the second lens element and the image surface.