Inclined Diffractive Gratings for Wide Field of View Waveguides
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Solution Overview
Problem
Optical transmission arrangements for display systems, such as HUDs and HMDs, face limitations in achieving a large field of view due to restrictions in the field angle spectrum, leading to edge regions being absent in transmitted images, particularly in formats like 16:9, and result in a complex structure with multiple light guides and coupling arrangements.
Innovation Solution
Incorporating diffractive input and output coupling gratings inclined at angles between 20° to 60° relative to the normal of the light guide interface, allowing for a single light guide to transmit fields of view up to 80° by enhancing the diffraction of light at large angles, thereby increasing the field angle spectrum without the need for multiple light guides or complex structures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If conventional coupling arrangements are used, then the structure remains simple, but the field of view is restricted and edge regions are absent
Solution Approach 1:
The patent applies parameter changes by inclining the diffractive gratings at specific angles (20°-60°) relative to the light guide interface normal. This angular parameter modification enables the gratings to diffract light at large angles, thereby expanding the field of view to up to 80° while maintaining a single light guide structure without requiring multiple stacked light guides
2Adaptability or versatility
If multiple light guides are used to increase field of view, then the field angle spectrum is improved, but the material thickness and device complexity increase
Solution Approach 1:
The patent modifies the grating inclination angle parameter to enable a single light guide to achieve field of view angles up to 80°, eliminating the need for multiple stacked light guides and reducing material thickness for smartglass integration
Solution Approach 2:
The patent introduces angular dimensionality by inclining the gratings relative to the light guide interface, utilizing the angular space more efficiently to expand the field angle spectrum within a single light guide rather than stacking multiple guides in the thickness direction
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 enables a larger field of view of up to 80° while maintaining a compact and less complex optical transmission arrangement, suitable for integration into spectacle lenses, by utilizing a single light guide and optimizing diffraction efficiency through inclined gratings.
Implementation Method 1
The input coupling arrangement has at least one diffractive input coupling grating, which is inclined at an angle in relation to a normal of an interface of the light guide arrangement
Implementation Method 2
by way of the input coupling arrangement having at least one diffractive input coupling grating
Implementation Method 3
light being guided in said light guide arrangement by way of total-internal reflection at optical interfaces of the optically denser material of the light guide arrangement to an optically thinner material
Implementation Method 4
the output coupling arrangement having at least one diffractive output coupling grating, which is inclined at an angle in relation to a normal of an interface of the light guide arrangement
Implementation Method 5
by way of the output coupling arrangement having at least one diffractive output coupling grating
Data Source
AI summary
An optical transmission assembly for transmitting a source image includes a waveguide assembly, an incoupling assembly for coupling light emitted from the source image into the waveguide assembly, and an outcoupling assembly for coupling the light guided in the waveguide assembly out of the waveguide assembly. The light emitted from the source image and coupled into the waveguide assembly can be propagated between the incoupling assembly and the outcoupling assembly in the waveguide assembly by means of a total reflection. The incoupling assembly has at least one diffractive incoupling grating which is inclined by an angle (α) ranging from 20° to 60° relative to a normal of a boundary surface of the waveguide assembly, and/or the outcoupling assembly has at least one diffractive outcoupling grating which is inclined by an angle (α) ranging from 20° to 60° relative to a normal of a boundary surface of the waveguide assembly.