LCP Gratings for Waveguide Intensity Uniformity
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Solution Overview
Problem
Augmented reality display systems using optical waveguides often suffer from non-uniform intensity distributions, leading to dark and light fringes and blotches in the replicated images, which are undesirable for user experience.
Innovation Solution
The apparatus includes a planar optical waveguide with an input-coupler, an intermediate-component, and an output-coupler, where one or more of these components are implemented as liquid crystal polymer (LCP) based surface relief gratings or double-side diffractive optical elements, enhancing light intensity distribution by optimizing pupil expansion and polarization rotation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If conventional waveguide components are used for image replication, then the device structure is simple, but non-uniform intensity distributions occur leading to dark and light fringes and blotches
Solution Approach 1:
The patent applies local quality by implementing anamorphic optics at specific locations within the waveguide system. The anamorphic input coupler and anamorphic output coupler are positioned at the input and output apertures respectively, creating localized optical transformations that correct intensity non-uniformities only where needed, rather than requiring complete system redesign
Solution Approach 2:
The patent changes optical parameters by introducing anamorphic transformation matrices that modify the beam shape and intensity distribution. The anamorphic optics alter the lateral magnification and focal ratios of the optical system, transforming the intensity distribution profile from non-uniform to uniform across the exit pupil
2Area of stationary object
If pupil expansion is performed to enlarge the eye box, then the field of view is improved, but intensity non-uniformity increases causing visible fringes
Solution Approach 1:
The patent uses composite optical systems by combining conventional waveguide components with anamorphic optical elements. The anamorphic input coupler and output coupler work together with the waveguide substrate to achieve both pupil expansion and intensity uniformity, creating a composite optical system that addresses multiple requirements simultaneously
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 improves the uniformity of light intensity distribution, reducing noticeable fringes and blotches, resulting in a more coherent and visually appealing augmented reality experience.
Implementation Method 1
The input-coupler couples light corresponding to an image into the bulk-substrate and towards the intermediate-component
Implementation Method 2
The intermediate-component performs horizontal or vertical pupil expansion and directs the light corresponding to the image towards the output-coupler
Implementation Method 3
The output-coupler performs the other one of horizontal or vertical pupil expansion and couples light corresponding to the image out of the waveguide
Implementation Method 4
one or more of the input-coupler, the intermediate-component or the output-coupler comprises a liquid crystal polymer (LCP) based surface relief grating (SRG)
Data Source
Figure 1A~1C
Figure 2
Figure 3~4
AI summary
An apparatus for use in replicating an image associated with an input-pupil to an output-pupil includes an optical waveguide including a bulk-substrate, an input-coupler, an intermediate-component and an output-coupler. The input-coupler couples light corresponding to the image into the bulk-substrate and towards the intermediate-component. The intermediate-component performs horizontal or vertical pupil expansion and directs the light corresponding to the image towards the output-coupler. The output-coupler performs the other one of horizontal or vertical pupil expansion and couples light corresponding to the image, which travels from the input-coupler to the output-coupler, out of the waveguide. The input-coupler, the intermediate-component and/or the output-coupler comprises a liquid crystal polymer based surface relief grating or a double-sided diffractive optical element to improve an intensity distribution of light output by the output-coupler.