VR Optical System Lens Arrangement for Ghosting Reduction
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Solution Overview
Problem
Current pancake-type virtual reality (VR) devices suffer from birefringence effects leading to ghosting and low light efficiency due to the use of polarized reflection sheets, and Fresnel lenses are difficult to design and process, causing glare and poor imaging.
Innovation Solution
An optical system comprising a first convex lens, a second meniscus lens, and a third meniscus lens with collinear principal optical axes, eliminating the need for polarized reflection sheets and using thin lenses with specific refractive index and Abbe number ratios to minimize chromatic aberration, while ensuring a small focal length and field of view.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If polarized reflection sheets are used in pancake-type VR devices, then device thickness can be reduced, but birefringence effects occur leading to ghosting and low light efficiency
Solution Approach 1:
The patent removes the polarized reflection sheet from the optical system, extracting the harmful element that causes birefringence and ghosting. The optical system achieves thickness reduction through a different mechanism - using a compact lens assembly with specific focal lengths and arrangements that eliminate the need for the polarized reflection sheet while maintaining imaging quality.
2Length of moving object
If Fresnel lenses are used to reduce device thickness, then device thickness can be reduced, but manufacturing difficulty increases and glare occurs leading to poor imaging
Solution Approach 1:
The patent employs standard spherical or aspherical lens surfaces that can be manufactured using conventional polishing and molding techniques, rather than requiring complex Fresnel lens fabrication. This approach uses readily manufacturable lens elements that achieve the desired optical performance without the manufacturing challenges of Fresnel lenses.
3Reliability
If multiple lenses with different refractive indices are used to correct chromatic aberration, then imaging quality improves, but device complexity increases
Solution Approach 1:
The patent combines multiple lens elements with different refractive indices and Abbe numbers into a unified optical assembly where the lenses work together to correct chromatic aberration. The meniscus lens with positive power and the biconcave lens with negative power are integrated in a compact arrangement that achieves chromatic correction while maintaining overall system compactness.
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 enhances imaging quality, reduces device thickness and weight, and achieves high light efficiency by avoiding stray light and glare, while maintaining a wide field of view and correcting chromatic aberration.
Implementation Method 1
The optical system includes a first lens, a second lens and a third lens that are sequentially arranged from an image side to an object side... The second lens has a positive power, the third lens has a negative power... a ratio of the refractive index of the second lens to the refractive index of the third lens is in a range from 0.85 to 1.15
Data Source
AI summary
An optical system, includes a first lens, a second lens and a third lens that are sequentially arranged from an image side to an object side, and principal optical axes of the first lens, the second lens and the third lens being collinear. The first lens is a convex lens, and at least one of the second lens and the third lens is a meniscus lens.