Switchable Metasurface DOE Using Fluid-Filled Grating Recesses
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Solution Overview
Problem
Existing augmented reality systems using waveguides with in-coupling diffraction gratings require large optics and increased image field size, leading to image quality degradation at the periphery, and there is a need for switchable diffractive optical elements that can be turned on and off.
Innovation Solution
A dynamically actuable diffractive optical element (DOE) with a substrate having a diffraction grating and a fluid region, where a fluid displacer is controlled by an electric signal to switch the grating between 'on' and 'off' states, altering its diffraction properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multiple waveguides with in-coupling diffraction gratings are used to couple light, then light coupling efficiency is improved, but image field size increases leading to image quality degradation at the periphery
Solution Approach 1:
The patent employs dynamically switchable diffraction gratings that can be activated or deactivated based on operational requirements. This dynamic control allows the system to optimize light coupling efficiency when needed while maintaining compact image field dimensions, thereby preventing image quality degradation at the periphery that would result from permanently enlarged optics
Solution Approach 2:
The invention utilizes variable refractive index materials or tunable diffraction grating parameters that can be adjusted to optimize optical performance. By changing these parameters dynamically, the system achieves efficient light coupling without permanently increasing the physical size of optical elements, thus maintaining image quality across the field
2Productivity
If the size of optics is increased to accommodate multiple waveguides, then light coupling capability is improved, but device weight and complexity increase
Solution Approach 1:
The patent implements dynamically controllable diffraction gratings that can be switched on and off as needed. This dynamic capability allows the system to achieve enhanced light coupling efficiency without permanently increasing the physical dimensions and weight of optical components, thereby maintaining a lightweight device design
3Adaptability or versatility
If switchable diffractive optical elements are implemented, then optical path control is improved, but device complexity increases
Solution Approach 1:
The patent replaces complex mechanical switching mechanisms with electrically or optically controlled diffraction gratings. This substitution enables dynamic control of optical paths through electrical signals or optical pumping, achieving versatile optical path management while avoiding the mechanical complexity and moving parts associated with traditional switching mechanisms
Solution Approach 2:
The invention employs diffraction gratings that can serve multiple functions: they act as beam splitters, waveguide couplers, and optical switches depending on their activation state. This multi-functionality reduces the need for separate components for each optical control function, thereby managing device complexity while enhancing adaptability
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
Enables efficient light coupling into multiple waveguides without increasing image field size, maintaining image quality, and providing a lightweight, switchable optical solution for augmented reality systems.
Implementation Method 1
A diffraction grating is an optical component that deflects light by an angle that is dependent on the wavelength of light and the angle of incidence on the grating
Implementation Method 2
The fluid has an index of refraction that is closer to an index of refraction of the diffraction grating than is an index of refraction of air or vacuum
Data Source
AI summary
A dynamically actuable lens includes a substrate having a surface and a metasurface diffractive optical element (DOE) formed on the surface. The metasurface DOE includes a plurality of raised portions and defines a plurality of recesses between adjacent raised portions. The dynamically actuable lens also includes a movable cover overlying the metasurface DOE and comprising a hydrophilic material, a quantity of a fluid disposed on the movable cover, and a drive mechanism coupled to the movable cover. The drive mechanism is configured to move the movable cover toward the metasurface DOE to displace a portion of the quantity of the fluid into the plurality of recesses, thereby rendering the metasurface DOE in an “off” state, and move the movable cover away from the metasurface DOE, causing the portion of the quantity of the fluid retracting from the plurality of recesses, thereby rendering the metasurface DOE in an “on” state.