Multilayer Liquid Crystal Gratings for Wide-Angle Light Redirection
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing augmented and virtual reality technologies face challenges in providing a comfortable and natural-feeling presentation of virtual image elements amidst real-world imagery due to the complexity of the human visual system, particularly in maintaining a match between accommodation and vergence for realistic depth perception.
Innovation Solution
The use of liquid crystal grating structures with varying tilt angles and compositions in diffractive optical elements to redirect light efficiently across a wide range of incident angles, integrated into display systems like waveguides, enhances the presentation of virtual content by aligning with the human visual system's depth perception mechanisms.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If conventional diffractive optical elements are used, then light redirection is achieved, but diffraction efficiency is limited at large incident angles
Solution Approach 1:
The diffractive optical element is divided into multiple sublayers, each with different grating orientations. This segmentation allows each sublayer to handle specific incident angle ranges, collectively achieving high diffraction efficiency across a wide angular range while maintaining overall system performance
Solution Approach 2:
Different regions of the diffractive optical element have locally optimized grating orientations tailored to specific incident angle ranges. This local quality variation ensures that light at different angles is efficiently redirected by the appropriately oriented sublayers, resolving the contradiction between efficiency and angular versatility
2Productivity
If virtual image elements are presented without transparency to real-world visual input, then immersive virtual reality experience is achieved, but natural visual perception is compromised
Solution Approach 1:
The system dynamically adapts between different optical configurations - switching between opaque VR mode for immersive experiences and transparent AR mode for natural visual perception. This dynamic capability allows the system to provide immersive VR when needed while avoiding visual discomfort by maintaining natural perception when appropriate
Solution Approach 2:
The optical device is designed with multi-functionality to operate in both VR and AR modes, as well as various intermediate states. This universality enables the system to deliver immersive virtual reality experiences while preserving natural visual perception options, thereby avoiding visual discomfort associated with purely opaque displays
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 increases the amount of light redirected with high efficiency, providing a more immersive and comfortable AR/VR experience by aligning with the human visual system's accommodation-vergence reflex, thereby improving depth perception and user comfort.
Implementation Method 1
liquid crystal grating structures with varying tilt angles and twist angles in diffractive optical elements to redirect light efficiently across a wide range of incident angles
Implementation Method 2
The liquid crystal sublayers are helically twisted so as to be helically or rotationally shifted in order to achieve a high diffraction efficiency at large diffraction angles
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
An optical device includes a stack of multiple grating structures, each of which includes a plurality of sublayers of liquid crystal material. Each sublayer of liquid crystal material includes laterally extending repeating units, each formed of a plurality of liquid crystal molecules. The repeating units of the liquid crystal layers are lateral offset from one another, and defined a tilt angle. The grating structures forming the stack of grating structure have tilt angles of different magnitudes. The grating structures may be configured to redirect light of visible or infrared wavelengths. Advantageously, the different tilt angles of the stack of grating structures allows for highly efficient diffraction of light incident on the grating structures at a wide range of incident angles.