Diffractive Waveguide Dispersion Compensation in AR
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Augmented reality devices face challenges in maintaining image quality and ergonomics due to the use of prisms, which cause light to refract and increase manufacturing costs, while also requiring complex designs to minimize dispersion.
Innovation Solution
The combination of a prism and a diffractive waveguide that compensates for refractive dispersion by adjusting the input and output couplers' structures and orientations, allowing the projector to be aligned within the frame arm while the waveguide is disposed at a wrap angle, thereby reducing image blur and manufacturing complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If a prism is used to refract light in the projection system, then the projector can be aligned with the waveguide, but chromatic dispersion causes image blur and requires complex compensation designs
Solution Approach 1:
A diffractive optical element (DOE) is introduced as an intermediary component between the prism and waveguide to compensate for chromatic dispersion. The DOE acts as a mediator that corrects the wavelength-dependent angular separation caused by the prism, restoring spectral alignment and eliminating image blur while maintaining the simplified projector alignment configuration.
Solution Approach 2:
The patent employs a diffractive optical element with specific grating parameters (period, orientation, depth) that are optimized to counteract the dispersion characteristics of the prism. By carefully selecting and adjusting these parameters, the system achieves chromatic compensation without requiring complex mechanical adjustments or additional optical components.
2Manufacturing precision
If complex dispersion compensation designs are implemented, then image quality is maintained, but device complexity and manufacturing cost increase
Solution Approach 1:
The patent replaces complex mechanical dispersion compensation mechanisms with a diffractive optical element that achieves the same function through optical diffraction principles. This substitution eliminates the need for moving parts, complex alignment mechanisms, or multiple optical components, thereby reducing device complexity while maintaining effective chromatic compensation.
Solution Approach 2:
By utilizing the wavelength-dependent diffraction properties of the DOE and carefully selecting its grating parameters, the system achieves dispersion compensation through parameter optimization rather than complex structural design. This approach simplifies the overall system while maintaining image quality.
3Ease of operation
If the waveguide is disposed at a wrap angle from the projector's major axis, then ergonomics are improved, but dispersion compensation becomes more challenging
Solution Approach 1:
The diffractive optical element serves as a mediator that decouples the ergonomic wrap angle configuration from dispersion compensation requirements. By placing the DOE in the optical path, it actively corrects chromatic dispersion regardless of the waveguide's angular orientation, allowing the system to maintain both ergonomic benefits and image quality without increased complexity.
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 configuration enhances ergonomics, reduces device size and weight, and maintains clear image quality while minimizing manufacturing costs by compensating for the refractive dispersion caused by the prism, resulting in improved usability and image clarity.
Implementation Method 1
The projection system includes a projector and a prism. The projector projects an image along the projectors major axis. The prism refracts the image having a first spectrum, a second spectrum, and a third spectrum.
Implementation Method 2
The waveguide includes an input coupler and an output coupler. The input coupler includes input structures at an input period and an input orientation and the input coupler is configured to receive the spectrums at different corresponding input angles. The output coupler includes output structures at an output period and an output orientation and the output coupler out couples the respective spectrums at an about equal output angle.
Data Source
AI summary
The present disclosure relates to augmented reality devices and related methods. In one or more embodiments, an augmented reality device includes a projection system and a waveguide. The projection system includes a projector and a prism. The projector projects an image along the projectors major axis. The prism refracts the image having a first spectrum, a second spectrum, and a third spectrum. The waveguide is disposed at a wrap angle from a plane formed from the major axis of the projector. The waveguide includes an input coupler and an output coupler. The input coupler includes input structures at an input period and an input orientation and the input coupler is configured to receive the spectrums at different corresponding input angles. The output coupler includes output structures at an output period and an output orientation and the output coupler out couples the respective spectrums at an about equal output angle.