Waveguide Incoupler Design for Laser Projection Double-Bounce Mitigation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional optical systems with waveguides face challenges in minimizing double-bounce losses, particularly when light interacts with the incoupler grating at varying angles, leading to inefficient light propagation and reduced image quality in near-eye display systems.
Innovation Solution
The proposed solution involves a laser projection system with a monolithic molded optical relay and a waveguide design where the laser light is scanned along a linear or arc path at the incoupler, reducing the incoupler region's form factor and minimizing double-bounce losses by ensuring light is incident at optimal angles for total internal reflection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If light is incident on the incoupler grating at varying angles, then the waveguide can accept light from different directions, but double-bounce losses increase and light propagation efficiency decreases
Solution Approach 1:
The patent applies local quality by making the incoupler region structurally distinct from the bulk waveguide. The incoupler is designed with specific grating characteristics and geometry optimized for light coupling, while the bulk waveguide maintains properties optimized for low-loss propagation. This localized optimization allows the incoupler to efficiently accept light at various angles while the bulk waveguide minimizes double-bounce losses through its geometry and surface quality.
2Area of stationary object
If the incoupler region size is reduced, then the overall device form factor decreases, but light coupling efficiency may be compromised
Solution Approach 1:
The patent employs parameter changes by optimizing the incoupler's geometric parameters (grating period, depth, orientation) and optical parameters (refractive index profile) to achieve high coupling efficiency in a reduced area. By carefully adjusting these parameters, the incoupler maintains effective light coupling despite the minimized footprint, resolving the contradiction between compact size and coupling performance.
3Ease of manufacture
If conventional waveguide designs are used, then manufacturing is simpler, but double-bounce losses are not minimized and image quality suffers
Solution Approach 1:
The patent applies segmentation by dividing the waveguide into functionally distinct regions: the incoupler region with optimized grating structures for light input, the bulk propagation region for low-loss transmission, and potentially an outcoupler region for light extraction. This segmentation allows each region to be optimized for its specific function while maintaining overall manufacturability, achieving both good image quality and reasonable fabrication 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 approach effectively reduces double-bounce losses, enhancing the efficiency of light propagation within the waveguide and improving image quality in near-eye display systems by optimizing the incoupler region's size and light incidence angles.
Implementation Method 1
minimizing double-bounce losses by ensuring light is incident at optimal angles for total internal reflection
Data Source
AI summary
A laser projection system utilizes a waveguide having a narrow incoupler for double-bounce mitigation and form factor reduction. An optical scanner includes an optical relay positioned in between two scan mirrors. The first scan mirror scans laser light into the optical relay in a first dimension, and the optical relay and converges the scanned laser light towards a second scan mirror. The second scan mirror scans laser light along a second dimension substantially perpendicular to a path over which the laser light is scanned across the second scan mirror, and the convergence introduced by the optical relay causes the laser light to be scanned as a line or arc path of an exit pupil plane that is coincident with the incoupler. The optical relay may include one or more lenses or may be a monolithic molded structure, which may be an Offner-style relay or a molded reflective relay.