Folded AR Optical Module With Shared Path and Polarization Routing
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Solution Overview
Problem
Existing diffractive waveguides in augmented reality (AR) technology suffer from low system efficiency and varying efficiency due to different propagation paths of light rays at different field of view, leading to poor display quality.
Innovation Solution
An optical module design incorporating a folded optical path with a turning element and a group of cemented lenses, including a beam splitter, phase retarders, and polarizing reflectors, which combines virtual and real image light rays into a shared optical path, enhancing imaging quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If diffractive waveguides are used as display schemes for augmented reality technology, then the near-eye display function is achieved, but the system efficiency is low and display quality is poor
Solution Approach 1:
The optical module is divided into multiple functional imaging elements (first imaging element with beam splitter and polarizing reflector, second imaging element with turning element) that independently process different light paths. This segmentation allows optimized control of virtual and real image light rays separately, improving overall system efficiency and display quality without the limitations of monolithic diffractive waveguide designs.
Solution Approach 2:
A polarizing beam splitter is introduced as an intermediary component to separate and redirect light paths based on polarization states. This mediator enables efficient routing of virtual image light from the display and real image light from the external environment through different optical paths, then combines them effectively, resolving the efficiency and quality issues of direct diffractive waveguide approaches.
2Adaptability or versatility
If diffractive waveguides are used, then augmented reality display is achieved, but the efficiency varies due to different propagation paths of light rays at different field of view
Solution Approach 1:
Different regions of the optical system are assigned different optical properties and functions. The first imaging element handles specific angular ranges with particular polarization control, while the second imaging element handles other ranges. This local optimization ensures high efficiency across the entire field of view by tailoring the optical path characteristics to the specific requirements of each viewing zone.
Solution Approach 2:
The optical system dynamically adapts to different field of view angles through the coordinated action of multiple imaging elements and polarizing components. As the viewing angle changes, the light automatically follows different propagation paths through the optical elements, which are designed to maintain optimal efficiency for each angular range, thus providing consistent performance across the full field of view.
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 achieves improved display quality by reducing chromatic aberration and module size, while maintaining excellent imaging quality across various wavelengths.
Implementation Method 1
a beam splitter, a first phase retarder and a first polarizing reflector arranged sequentially between lens elements of the lens group
Implementation Method 2
a first phase retarder and a first polarizing reflector arranged sequentially between lens elements of the lens group
Implementation Method 3
a first phase retarder and a first polarizing reflector arranged sequentially between lens elements of the lens group
Implementation Method 4
a second imaging element including an turning element and a second polarizing reflector disposed on either side of the turning element
Implementation Method 5
a first imaging element including a lens group arranged along a same optical axis
Data Source
Figure 1
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AI summary
Embodiments of the present application provide an optical module and a head-mounted display device. The optical module comprises a display, a first imaging element, and a second imaging element. The first imaging element comprises a lens group arranged along the same optical axis, and a light splitting element, a first phase retarder and a first polarization reflector which are sequentially arranged between optical paths of the lens group. A first included angle is formed between the optical axis of the first imaging element and the central axis of the display, and the focal power ϕ1 of the first imaging element is zero. The second imaging element comprises a turning element and a second polarization reflector arranged on any side of the turning element, the second imaging element is located between the display and the first imaging element, and a second included angle is formed between the second imaging element and the optical axis of the first imaging element. According to a novel optical framework provided by the embodiments of the present application, a folding optical path matches the turning element, so that an AR optical scheme that a virtual picture and a real picture share an optical path is realized.