Prism Optical System for Head-Mounted Display Field Curvature Correction
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Solution Overview
Problem
Existing head-mounted display devices face challenges in achieving a balance between miniaturization, lightweight design, and providing a large field of view while correcting field curvature and pupil shift distortion, which affects the user's imaging experience.
Innovation Solution
An optical system comprising an image source, a first prism, a lens, and a reflective film is designed to optimize the optical path length and path differences, with specific ratios and configurations of optical elements to ensure a larger eye box and eye relief, correcting field curvature and pupil shift distortion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the optical path length is extended to correct field curvature and pupil shift distortion, then imaging quality is improved, but the device volume and weight increase
Solution Approach 1:
The patent introduces a prism component that redirects the optical path in a dimensional direction perpendicular to the original optical axis. This allows the optical path to be extended in three-dimensional space without increasing the linear dimensions of the device, thereby correcting field curvature and pupil shift distortion while maintaining compact device volume.
Solution Approach 2:
The optical elements including the prism, lens, and reflective film are nested within each other in a compact arrangement. The prism contains the optical path, while the lens and reflective film are positioned within or adjacent to the prism structure, creating a nested configuration that maximizes optical path length within minimal device volume.
2Volume of stationary object
If the optical system is miniaturized, then device volume and weight are reduced, but the field of view and eye box size are limited
Solution Approach 1:
The prism redirects light rays through a perpendicular dimension, allowing the optical path to fold back on itself. This dimensional change enables the system to achieve a larger effective field of view and eye box area by utilizing spatial folding rather than linear expansion, keeping the device compact while expanding the functional optical aperture.
3Adaptability or versatility
If the optical path length is increased to accommodate users with different interpupillary distances, then adaptability is improved, but the device complexity increases
Solution Approach 1:
The prism-lens-reflective film assembly serves multiple functions simultaneously: it corrects field curvature, corrects pupil shift distortion, extends the optical path, and provides adaptability for different interpupillary distances. This multi-functionality is achieved through a single integrated optical configuration rather than multiple separate components, thereby improving adaptability while controlling device complexity.
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 enables a miniaturized and lightweight optical system with a larger field of view, accommodating users with different interpupillary distances and allowing users to wear glasses without removing them, while maintaining high imaging quality.
Implementation Method 1
light rays emitted by the image source enters from the first surface of the first prism, undergo at least one total reflection within the first prism, and then exits through the third surface of the first prism
Implementation Method 2
a lens arranged close to the third surface of the first prism
Implementation Method 3
a reflective film arranged on the side of the second lens away from the third surface of the first prism; the light rays reflected by the reflective film exit after passing through the first prism again
Data Source
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AI summary
Embodiments of the present disclosure disclose an optical system and a head-mounted display device. The specific implementation solution is as follows: the optical system comprises: an image source; a first prism having a first surface, a second surface, and a third surface, wherein the first surface is arranged close to the first lens; a lens arranged close to the third surface, wherein a second surface of the first prism is away from the lens; a reflective film arranged on the side of the second lens away from the third surface; wherein light emitted by the image source enters from the first surface of the first prism, undergoes at least one total reflection within the first prism, and then exits through the third surface to the second lens. Among the light rays emitted by the image source, the light ray propagating along the optical axis of the optical system passes through a preset optical path length d within the first prism when passing through the first prism for the first time; the light rays reflected by the reflective film exit after passing through the first prism again; and the ratio f/d of the system focal length f of the optical system to d is greater than or equal to 0.45 and less than or equal to 0.60.