Waveguide Diffractive Elements Recycle Zero-Order Light
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Solution Overview
Problem
Conventional waveguides with diffractive/holographic elements suffer from significant light loss, leading to reduced light intensity for human eyes and increased ghost/stray light production.
Innovation Solution
A waveguide device and optical engine design that includes a first diffractive element, a second diffractive element, a third diffractive element, and a waveguide element, where the second diffractive element reflects and recycles the zero-order light back into the waveguide, allowing it to be further diffracted by the third diffractive element, thereby increasing light intensity by at least 50%.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If conventional diffractive elements are used in waveguides, then the device structure is simple, but light loss is significant (40% or more intensity loss)
Solution Approach 1:
The patent recovers the zero-order light that would otherwise be lost by redirecting it through additional diffractive elements back into the waveguide, converting waste light into useful output and increasing overall light efficiency
Solution Approach 2:
The patent introduces intermediary diffractive elements (second and third diffractive elements) that act as mediators to capture and redirect the zero-order light, transforming it from a harmful loss into a beneficial contribution to the final image output
2Device complexity
If conventional diffractive elements are used in waveguides, then the device structure is simple, but ghost/stray light is easily produced
Solution Approach 1:
The patent converts the harmful zero-order light (which causes ghost images and stray light) into a beneficial component by redirecting it through additional diffractive elements to contribute to the final image output, thereby eliminating the harmful effect while maintaining simplicity
3Speed
If light is diffracted by diffractive elements, then the light propagates at specific angles, but the zero-order light directly exits causing intensity loss
Solution Approach 1:
The patent segments the light handling function into multiple diffractive elements, where the first element creates the zero-order light and the second and third elements specifically target and redirect this zero-order light, allowing independent optimization of each element's function
Solution Approach 2:
The patent adds another dimensional aspect to light control by introducing multiple diffractive elements that operate in sequence, transforming the single-stage diffraction into a multi-stage process that recovers and redirects light in a new spatial dimension
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 proposed solution effectively recycles lost light, significantly increasing the intensity of light outputted by the optical engine, thereby enhancing the performance of augmented reality display systems by reducing light loss and ghost light production.
Implementation Method 1
The first diffractive element has a first grating configured to diffract light of a wavelength to propagate with a first diffraction angle
Implementation Method 2
The second diffractive element has a second grating configured to diffract the light of the wavelength to propagate with a second diffraction angle
Implementation Method 3
The third grating is configured to diffract the light of the wavelength to propagate with the first diffraction angle
Implementation Method 4
The fourth grating is configured to diffract the light of the wavelength to propagate with the second diffraction angle
Implementation Method 5
The waveguide element is configured to guide light propagated from the first diffractive element and the second diffractive element to the third diffractive element
Data Source
AI summary
A waveguide device includes a first diffractive element, a second diffractive element, a third diffractive element, and a waveguide element. The first diffractive element has a first grating configured to diffract light of a wavelength to propagate with a first diffraction angle. The second diffractive element has a second grating configured to diffract the light of the wavelength to propagate with a second diffraction angle. The third diffractive element has a third grating and a fourth grating. The third grating is configured to diffract the light of the wavelength to propagate with the first diffraction angle. The fourth grating is configured to diffract the light of the wavelength to propagate with the second diffraction angle. The waveguide element configured to guide light propagated from the first diffractive element and the second diffractive element to the third diffractive element.