AR Projection Module Integration for Higher Resolution and Less Ghosting
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Solution Overview
Problem
Existing augmented reality (AR) display devices face limitations due to a low refractive index difference at the interface of the projection source and beam shaping element, leading to reduced resolution, stray light, and a large, cumbersome optical structure.
Innovation Solution
Integration of the projection source and beam shaping element into a unitary piece, using an intermediate matching medium with a refractive index greater than 1, such as a liquid or liquid crystal medium, to reduce refractive index differences and enhance light transmittance, while incorporating a polarizing beamsplitter and wave plate to minimize ghost images and interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the projection source and beam shaping element are separated by air, then the optical structure is simple and easy to manufacture, but the numerical aperture is difficult to increase and the resolution is limited
Solution Approach 1:
The patent integrates the projection source and beam shaping element into a unified structure by filling the gap between them with an intermediate matching medium having refractive index between 1.3 and 2.6. This merging eliminates the air gap interface, increases the numerical aperture to greater than 0.7, and improves resolution without significantly complicating the optical structure
Solution Approach 2:
The patent introduces an intermediate matching medium with refractive index between 1.3 and 2.6 as a mediator between the projection source and beam shaping element. This intermediary substance fills the gap and optimizes light transmission, enabling higher numerical aperture and resolution while maintaining structural simplicity
2Ease of manufacture
If the projection source and beam shaping element are separated by air, then the assembly is easy to manufacture, but relatively more light is reflected at the interface generating stray light and ghost phenomenon
Solution Approach 1:
The intermediate matching medium serves as an intermediary that eliminates the high refractive index difference at the air-lens interface. By filling the gap with material having refractive index between 1.3 and 2.6, it reduces reflection and stray light generation while maintaining ease of assembly through simple gap filling
Solution Approach 2:
The patent changes the refractive index parameter of the medium between projection source and beam shaping element from air (n=1.0) to an intermediate medium (n=1.3-2.6). This parameter change reduces the refractive index difference at interfaces, minimizing reflection and ghost phenomenon while preserving manufacturing simplicity
3Ease of operation
If the projection source and beam shaping element are discrete and separate components, then the optical structure is easy to assemble, but the structure is large in size and easily damaged
Solution Approach 1:
The patent merges the discrete projection source and beam shaping element into a more integrated structure by filling the gap with intermediate matching medium. This creates a unified optical module that is more compact and mechanically stronger while maintaining ease of assembly through the simple gap-filling process
Solution Approach 2:
The patent uses composite material approach by combining the projection source, beam shaping element, and intermediate matching medium into an integrated optical module. This composite structure enhances mechanical strength and compactness while preserving assembly simplicity
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
Improves light efficiency, reduces ghost images, and results in a more compact, easily assembled, and comfortable AR display device with enhanced brightness and resolution.
Implementation Method 1
Due to a low refractive index of the air, a numerical aperture is difficult to increase, and a limit resolution of a system is limited. Due to a large refractive index difference at an interface of the lens 2 with the air, i.e. at an incident surface of the light, relatively more light is reflected at the interface, generating more stray light and resulting in serious ghost phenomenon
Implementation Method 2
the optical path module comprises a beamsplitter and a curved reflector
Implementation Method 3
at a beamsplitting side of the beamsplitter 3, a portion of the light is reflected onto a reflecting surface of the reflector 4
Data Source
Figure 1~3
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Figure 5~6
AI summary
The application provides an augmented reality display device comprising a projection source module and an optical path module, the projection source module comprising a projection source (12) and a beam shaping element (14) which are integrated into a unitary piece, and the optical path module comprising a beamsplitter (20) and a reflector (60), wherein virtual image light (VL) emitted from the projection source (12) and carrying virtual image information is emitted out of the projection source module after being shaped by the beam shaping element (14), projected onto the beamsplitter (20) first, then reflected onto the reflector (60) by the beamsplitter (20), then reflected by the reflector (60), and enters a human eye (E) eventually, and scene light (AL) carrying real scene information enters the reflector (60) from an outside of the reflector (60), and is transmitted through the reflector (60) and the beamsplitter (20) into the human eye (E). The application also provides a wearable augmented reality system comprising the augmented reality display device and the projection source module for the augmented reality display device.