AR Waveguide Diffractive Structure for Spatial Uniformity
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Solution Overview
Problem
Existing augmented and virtual reality displays face challenges in achieving spatial uniformity of optical output while maintaining a wide angular field of view.
Innovation Solution
Incorporating an intermediate diffractive optical structure between the input grating and the output diffractive optical structure in a waveguide, which provides a one-dimensional expansion of light through double diffraction, ensuring self-conjugation and minimizing undesirable optical effects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If an intermediate diffractive optical structure is added to improve spatial uniformity, then spatial uniformity of optical output is improved, but device complexity increases
Solution Approach 1:
The optical path is segmented into three distinct diffractive optical structures: an input grating, an intermediate diffractive optical structure, and an output grating. The intermediate structure is further segmented into multiple zones with different diffraction characteristics, allowing independent optimization of different spatial regions to achieve uniform optical output across the entire field of view.
Solution Approach 2:
An intermediate diffractive optical structure is introduced as a mediator between the input and output gratings. This intermediate structure performs a first diffraction that expands the optical beam in one dimension, creating a more uniform spatial distribution before the light reaches the output grating, thereby improving overall spatial uniformity without compromising the primary coupling function.
2Manufacturing precision
If diffraction is used to expand light in one dimension, then spatial uniformity is improved, but angular field of view may be reduced
Solution Approach 1:
The diffraction parameters of the intermediate structure are carefully controlled and optimized. By adjusting the grating period, groove depth, and orientation of the intermediate diffractive structure, the patent achieves one-dimensional beam expansion while maintaining minimal impact on the angular field of view. The design parameters are selected to provide the necessary spatial uniformity while preserving wide angular coverage for both augmented and virtual reality applications.
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 approach enhances spatial uniformity of the optical output and preserves a wide angular field of view, improving the overall performance and user experience in augmented and virtual reality displays.
Implementation Method 1
Light from the projector is coupled into the waveguide by a diffraction grating (an input grating)
Implementation Method 2
an intermediate diffractive optical structure configured to receive light from the input diffractive optical structure, provide a one-dimensional expansion of the received light, and couple the expanded light towards the output diffractive optical structure
Implementation Method 3
The light is then coupled out of the waveguide by another diffraction grating (an output grating) so that it can be viewed by a user
Implementation Method 4
The projected light is totally internally reflected within the waveguide
Data Source
AI summary
A device is disclosed comprising a waveguide (2; 102), an input diffractive optical structure (4; 104) configured to receive light from a projector and couple the received light into the waveguide and an output diffractive optical structure (10; 110). An intermediate diffractive optical structure (6, 8; 106) is configured to receive light from the input diffractive optical structure (4; 104), provide a one-dimensional expansion of the received light, and couple the expanded light towards the output diffractive optical structure (10; 110). The output diffractive optical structure (10; 110) is configured to receive light from the intermediate diffractive optical structure and couple it towards a viewer. The intermediate diffractive optical structure (6, 8; 106) comprises diffractive features that are oriented at a first angle to light received from the input diffractive optical structure to provide a first diffraction and a second diffraction within the intermediate diffractive optical structure in order to couple light towards the output diffractive optical structure. The first diffraction couples light from the input diffractive optical structure towards the diffractive features at a second angle so that the second diffraction is provided at a plurality of spaced positions in the intermediate diffractive optical structure thereby providing the one-dimensional expansion of light. The second diffraction couples light towards the output diffractive optical structure.