AR Waveguide Out-Coupling Grating Partitioning for Uniform Brightness
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing AR/MR glasses using diffractive optical waveguides suffer from non-uniform brightness in the field of view due to varying diffraction efficiencies of light beams at different angles, which is not suitable for mass production and affects user experience.
Innovation Solution
Optimize grating parameters of the coupling-in and coupling-out gratings in AR optical waveguides to ensure uniform diffraction efficiencies across different angles and partitions, partitioning the coupling-out grating to minimize perceptible brightness changes, and adjust grating duty ratios to compensate for light attenuation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If diffractive optical waveguide is used for AR/MR glasses, then mass production capability and device thinness are improved, but non-uniform brightness in field of view occurs
Solution Approach 1:
The coupling-out grating is divided into multiple partitions along the propagation direction of light beams. Each partition has independently optimized grating duty ratios to compensate for light attenuation at different positions, ensuring uniform brightness across the field of view while maintaining mass production capability through a systematic design approach
Solution Approach 2:
Different grating duty ratios are applied to different partitions of the coupling-out grating based on local light attenuation characteristics. This local optimization ensures that each region contributes uniformly to the overall brightness, resolving the non-uniform brightness issue while keeping the device suitable for mass production
2Device complexity
If array optical waveguide is used, then design simplicity is improved, but manufacturing difficulty increases and mass production is restricted
Solution Approach 1:
The invention transitions from array waveguide geometry to diffractive grating parameters optimization. By changing the design approach from structural arrangement to parameter tuning (grating duty ratios, periods, depths), the solution achieves both design simplicity and manufacturing ease suitable for mass production
3Illumination intensity
If grating duty ratios are optimized for uniform brightness, then brightness uniformity is improved, but manufacturing precision requirements increase
Solution Approach 1:
By segmenting the grating into partitions with gradually varying duty ratios, the invention reduces the precision requirement for each individual partition compared to requiring perfect uniformity across the entire grating. This stepwise optimization makes high brightness uniformity achievable with standard manufacturing tolerances
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
Achieves uniform brightness across the field of view, improving user experience and facilitating mass production by reducing manufacturing complexity and light loss.
Implementation Method 1
a coupling-in grating 110, configured to couple light beams generated by an optical machine into the optical waveguide
Implementation Method 2
an optical waveguide body 120... Light beams in different directions in the light beam group
Implementation Method 3
a coupling-out grating 130... the coupling-out diffraction efficiencies of the respective partitions are different, thereby improving the situation where an image transmitted through the AR optical waveguide exhibits a change in brightness
Data Source
Figure 1
Figure 2
Figure 3
AI summary
The disclosure provides a design method of a coupling-out grating of an AR optical waveguide, the AR optical waveguide including a coupling-in grating, an optical waveguide body and the coupling-out grating, and the design method including: S101: calculating a diffraction coupling-in angle, at which a light beam is diffracted and coupled into the optical waveguide body through the coupling-in grating, according to an angle at which the light beam is incident to the coupling-in grating, a wavelength of the light beam and a grating period of the coupling-in grating; S102: calculating a distance between two adjacent coupling-out positions of the light beam on the coupling-out grating according to the diffraction coupling-in angle and a thickness of the optical waveguide body; S103: calculating a brightness difference rate of the light beam after being coupled out multiple times through the coupling-out grating according to the maximum diffraction efficiency of the coupling-out grating; and S104: calculating the number of partitions of the coupling-out grating according to a length of the coupling-out grating, a sensitivity of a human eye to the light beam, the brightness difference rate, and the distance between the two adjacent coupling-out positions.