Active Optical Engine With Wave Plate Switching for Wider FOV
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Solution Overview
Problem
Existing near-eye display systems face challenges in expanding the field of view (FOV) without increasing the size, weight, and power consumption of projectors, which is particularly problematic for small, lightweight, and energy-efficient devices like head-mounted displays and smart glasses.
Innovation Solution
The use of an active wave plate to switch the polarization of light beams between P and S polarizations, combined with a polarizing beam splitter and multiple light-guide optical elements, allows for the expansion of the FOV by selectively activating facets to redirect light beams at different angles, thereby reducing the optical and physical demands on the projector.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If the projector size is increased to expand the field of view, then the FOV is improved, but the device weight and power consumption increase
Solution Approach 1:
The optical system is divided into multiple light-guide optical elements (first LOE component, second LOE component, third LOE component), each handling specific portions of the light beam to create different facets of the expanded field of view. This segmentation allows the projector to maintain a compact size while achieving a wide FOV through distributed optical processing.
Solution Approach 2:
Light-guide optical elements act as intermediaries between the projector and the user's eye. These elements guide and redirect light beams through multiple internal reflections and coupling-out facets, expanding the apparent field of view without requiring the projector itself to be larger or more powerful.
2Area of stationary object
If the projector size is increased to expand the field of view, then the FOV is improved, but the device power consumption increases
Solution Approach 1:
The optical system is divided into multiple light-guide optical elements (first LOE component, second LOE component, third LOE component), each handling specific portions of the light beam to create different facets of the expanded field of view. This segmentation allows the projector to maintain a compact size while achieving a wide FOV through distributed optical processing.
Solution Approach 2:
Light-guide optical elements act as intermediaries between the projector and the user's eye. These elements guide and redirect light beams through multiple internal reflections and coupling-out facets, expanding the apparent field of view without requiring the projector itself to be larger or more powerful.
3Area of stationary object
If multiple optical paths are added to expand FOV, then the field of view is improved, but the device complexity increases
Solution Approach 1:
Multiple light-guide optical elements are combined in a stacked configuration, sharing common interfaces and optical paths where possible. The first and second LOE components share a first common interface, while the second and third LOE components share a second common interface, reducing overall system complexity compared to completely separate optical systems.
Solution Approach 2:
The active wave plate serves multiple functions: it controls polarization state, enables selective activation of different optical paths, and facilitates the switching between different field of view components. This multi-functionality reduces the need for separate control mechanisms for each optical path.
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 enables a wider, immersive FOV without significantly increasing the size, weight, or power consumption of the projector, providing a more comfortable and efficient near-eye display experience.
Implementation Method 1
The active wave plate is configured to convert the light beam output by the projection optics device from the first polarization to a second polarization when in the activated state
Implementation Method 2
a PBS that is configured to redirect light beams having the first polarization and to allow light beams having the second polarization to pass therethrough
Data Source
Figure 1A
Figure 1B
Figure 2
AI summary
In an embodiment, an apparatus is disclosed that includes at least one processor configured to determine a target coupling-out facet, identify an optical path to the target coupling-out facet, identify an active wave plate corresponding to the optical path, determine a target state of the active wave plate that corresponds to the optical path, set the active wave plate to the identified target state and cause a projection device to project a light beam comprising an image field of view component along the identified optical path.