Polarization Recycling Structures for Efficient Waveguide Coupling
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Solution Overview
Problem
Designing electronic devices with displays, such as virtual and augmented reality headsets, is challenging due to unsightly and bulky components that do not achieve desired optical performance levels.
Innovation Solution
Incorporating polarization recycling structures with a polarizing beam splitter, prism, and waveplates between the display module and waveguide to convert unpolarized light into linearly polarized light, maximizing optical efficiency and minimizing light saber artifacts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If polarization recycling structures are added to convert unpolarized light into linearly polarized light, then optical efficiency is maximized and light saber artifacts are minimized, but device complexity increases
Solution Approach 1:
The patent combines the polarizing beam splitter and waveplates into an integrated polarization recycling structure that is mounted directly on the input coupler of the waveguide. This merging of components achieves the desired optical performance (maximizing light coupling efficiency and minimizing light saber artifacts) while reducing the overall device complexity by eliminating the need for separate alignment mechanisms and housing structures.
Solution Approach 2:
The polarization recycling structure acts as an intermediary component between the display module and the waveguide input coupler. It converts unpolarized light from the display module into linearly polarized light that is optimally coupled into the waveguide, thereby improving optical efficiency without requiring changes to the display module or waveguide themselves.
2Illumination intensity
If polarization recycling structures are used to maximize light coupling into the waveguide, then the amount of light provided to the eye box is maximized, but the device becomes bulkier
Solution Approach 1:
The polarization recycling structure is nested onto the input coupler of the waveguide, utilizing the existing optical path and mounting surfaces. The waveplates are mounted directly on the input coupler, and the polarizing beam splitter is integrated into the same optical path, allowing the structure to be compact and not increase the overall device volume significantly.
Solution Approach 2:
The patent utilizes the z-dimensional space above the input coupler surface to mount the waveplates and position the polarizing beam splitter, rather than expanding the lateral footprint of the device. This allows the polarization recycling function to be added without increasing the device's width or depth, maintaining a compact form factor.
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
Maximizes the amount of light coupled into the waveguide and provided to the eye box, while reducing unsightly artifacts, thereby enhancing optical performance and uniformity of the displayed images.
Implementation Method 1
The polarizing beam splitter may transmit a first portion of the unpolarized light as first image light having a first linear polarization. The polarizing beam splitter may reflect a second portion of the unpolarized light as second image light having a second linear polarization.
Implementation Method 2
One or more waveplates may be mounted to the prism for transmitting the second image light. The one or more waveplates may include a half waveplate or a pair of quarter waveplates. Upon transmission by the one or more waveplates, the second image light may have the same linear polarization as the first image light.
Implementation Method 3
The input coupler may be a reflective input coupling prism or a transmissive input coupling prism
Implementation Method 4
The input coupler may be a reflective input coupling prism or a transmissive input coupling prism
Implementation Method 5
The waveguide may have an input coupler and an output coupler
Data Source
AI summary
A display may include a waveguide for providing light to an eye box. The display may include polarization recycling structures having a polarizing beam splitter and a prism. The polarizing beam splitter may transmit a first portion of unpolarized light as first image light having a first polarization and may reflect a second portion of the unpolarized light as second image light having a second polarization. One or more waveplates may be mounted to the prism for transmitting the second image light. Upon transmission by the waveplate(s), the second image light may have the same polarization as the first image light. An input coupler may couple the first and second image light into the waveguide. Providing polarized light to the waveguide may maximize the optical efficiency of the waveguide. The polarization recycling structures may maximize the amount of the image light that is coupled into the waveguide.