Folded Polarization Optical Layout for Compact AR/VR Imaging
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Solution Overview
Problem
Current optical systems for AR/VR head-mounted devices suffer from issues such as low imaging clarity, poor image stability, and insufficient system compactness.
Innovation Solution
A four-lens optical system design comprising a first lens with positive refractive power, a reflective polarizing element, a quarter-wave plate, a second lens with positive power, a third lens with negative power, a partially reflective element, a second quarter-wave plate, and a polarizer, with specific ratios and configurations of focal lengths, thicknesses, and refractive indices to optimize aberration performance, imaging clarity, and compactness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If a catadioptric optical system with multiple lenses and optical elements is used, then the field of view is enlarged and glare is reduced, but the system complexity and volume increase
Solution Approach 1:
The optical system is divided into distinct functional modules: a catadioptric optical system for field expansion and glare reduction, and a separate image display device for image presentation. This segmentation allows each module to be optimized independently while reducing overall system complexity.
Solution Approach 2:
The patent utilizes folded optical paths and multi-dimensional light manipulation through the catadioptric system, employing mirrors and lenses arranged in three-dimensional space to achieve extended field of view without proportionally increasing system volume.
2Area of stationary object
If a catadioptric optical system with multiple lenses and optical elements is used, then the field of view is enlarged and glare is reduced, but the system volume increases
Solution Approach 1:
The optical elements are arranged in a compact, nested configuration where the folded optical path allows components to be positioned within each other's spatial envelopes, achieving extended optical functionality within a minimized physical volume.
Solution Approach 2:
The system employs three-dimensional optical folding techniques, using mirrors and lens arrangements that manipulate light paths in multiple spatial dimensions, thereby achieving large field of view with compact physical footprint.
3Device complexity
If conventional optical systems are used, then the structure is simple, but the imaging clarity and image stability are insufficient
Solution Approach 1:
The optical system employs a composite design combining refractive elements (lenses) and reflective elements (mirrors) in a catadioptric configuration, leveraging the complementary strengths of both optical approaches to achieve superior imaging clarity and stability while maintaining reasonable system complexity.
Solution Approach 2:
The patent introduces a polarizing beam splitter as an intermediary element that separates and recombines light paths, enabling precise control over light propagation and improving image stability without requiring overly complex optical arrangements.
4Device complexity
If conventional optical systems are used, then the structure is simple, but the image stability is poor
Solution Approach 1:
The catadioptric design combines reflective and refractive optical elements with rigid mechanical mounting structures, creating a stable optical path that is less sensitive to vibrations and environmental disturbances, thereby improving image stability without excessive complexity.
Solution Approach 2:
The polarizing beam splitter serves as a stable intermediary that provides fixed, well-defined light paths with precise angular relationships, enhancing image stability through its inherent polarization-based light separation mechanism.
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 design improves imaging clarity, stability, and reduces the system's volume and weight, enhancing portability and user comfort by optimizing aberration performance and achieving a compact optical system.
Implementation Method 1
a reflective polarizing element
Implementation Method 2
a reflective polarizing element
Implementation Method 3
a first quarter-wave plate; a second quarter-wave plate
Implementation Method 4
a first lens with positive refractive power; a second lens with positive refractive power; a third lens with negative refractive power; a fourth lens with negative refractive power
Implementation Method 5
a partially reflective element
Data Source
AI summary
Disclosed is an optical system, sequentially including along the optical axis from a first side to a second side: a first lens having positive refractive power, its first side surface being convex and its second side surface being planar; a reflective polarizing element; a first quarter-wave plate; a second lens having positive refractive power, its first side surface being convex; a third lens having negative refractive power, its first side surface being concave and its second side surface being planar; a partially reflective element; a second quarter-wave plate; a polarizer; and a fourth lens having negative refractive power; wherein the number of lenses with refractive power in the optical system is four; the effective focal length f1 of the first lens and the effective focal length f3 of the third lens satisfy: −1.5<f3/f1<−1.0; and it is satisfied:2≤(CT3+CTQ2+CTL)/(CT1+CTR+CTQ1)<2.9.