Diffractive Optical Waveguide Total Reflection Layer Color Uniformity
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Solution Overview
Problem
Existing diffractive waveguides suffer from non-uniform color due to inadequate propagation distances and exit pupil densities of red, green, and blue light, leading to poor color uniformity and reliability issues such as attachment parallelism and bubble formation between layers.
Innovation Solution
A diffractive optical waveguide with a stacked total reflection layer comprising a high refractive index first light propagation layer and a low refractive index second light propagation layer, deposited via a deposition method, along with coupling-in and coupling-out gratings, which enhances light reflection and pupil expansion, improving color uniformity and reliability by avoiding attachment problems.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single-layer high refractive index total reflection layer is used, then the structure is simple, but the propagation distance and exit pupil density of light are insufficient, resulting in poor color uniformity
Solution Approach 1:
The total reflection layer is segmented into two distinct layers: a first light propagation layer with high refractive index and a second light propagation layer with low refractive index. This segmentation allows each layer to perform specific optical functions, with the high refractive index layer providing strong light confinement and the low refractive index layer enabling sufficient propagation distance and exit pupil density, thereby achieving good color uniformity while maintaining reasonable structural complexity.
2Manufacturing precision
If the second light propagation layer is attached to the first light propagation layer, then the light propagation performance is improved, but attachment problems such as poor parallelism, bubbles and attachment failure occur
Solution Approach 1:
The mechanical attachment process is replaced with a deposition process. The second light propagation layer is deposited directly onto the first light propagation layer through vapor deposition or similar techniques, eliminating the need for mechanical bonding. This substitution avoids attachment-related problems such as poor parallelism, bubble formation, and attachment failure, while ensuring reliable inter-layer coupling and improved light propagation performance.
3Manufacturing precision
If the second light propagation layer is deposited via deposition method, then the propagation distance and exit pupil density of red, green and blue light are improved, but the deposition process control complexity increases
Solution Approach 1:
The deposition process is controlled by adjusting key parameters such as deposition thickness, deposition rate, and material composition. By optimizing these parameters, the second light propagation layer achieves the desired optical properties including sufficient propagation distance and exit pupil density for red, green, and blue light. The parameter-based control approach provides a systematic method to manage deposition complexity while achieving precise optical performance.
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 solution effectively improves color uniformity by enhancing light propagation and exit pupil densities, while ensuring reliable attachment and design flexibility through controlled deposition thickness and material type of the second light propagation layer.
Implementation Method 1
the total reflection layer includes a first light propagation layer and a second light propagation layer, which are disposed in a stacked manner... light emitted from the first light propagation layer may be reflected in the second light propagation layer
Data Source
AI summary
The present invention provides a diffractive optical waveguide and a preparation method thereof, and an augmented reality display device. The diffractive optical waveguide includes: a total reflection layer, wherein the total reflection layer includes a first light propagation layer and a second light propagation layer, which are disposed in a stacked manner, a refractive index of the second light propagation layer is less than a refractive index of the first light propagation layer, and the second light propagation layer is deposited on one surface of the first light propagation layer via a deposition method; and a coupling-in grating and a coupling-out grating, wherein the coupling-in grating and the coupling-out grating are disposed at intervals on a side of the first light propagation layer that faces away from the second light propagation layer.