Liquid Crystal Grating Beam Steering for HMDs
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Solution Overview
Problem
Conventional head-mounted displays are bulky and heavy due to complex optics, leading to user discomfort and inefficiencies in virtual and augmented reality experiences due to chromatic dispersion and optical artifacts.
Innovation Solution
A compact and lightweight head-mounted display device utilizing a combination of a pixel array and microlens tiles, with a beam steering device that sequentially transmits light of different colors using specific voltages to reduce chromatic dispersion and enhance efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If conventional complex optics are used in head-mounted displays, then beam steering capability is achieved, but device weight and size increase causing user discomfort
Solution Approach 1:
The patent replaces conventional mechanical/optical beam steering systems with an electro-optic liquid crystal grating system. The liquid crystal grating uses electric fields to control light diffraction, eliminating the need for heavy mechanical moving parts or complex optical assemblies, thereby significantly reducing device weight while maintaining beam steering capability.
Solution Approach 2:
The patent dynamically changes the phase retardation parameter of the liquid crystal grating by applying different voltages to steer light beams to different locations. This parameter-based control method replaces physical reconfiguration of optical paths, enabling lightweight compact design while achieving precise beam steering.
2Volume of moving object
If electro-optic elements are used for beam steering, then device compactness is improved, but chromatic dispersion occurs causing optical artifacts
Solution Approach 1:
The patent employs sequential color transmission, cycling through different wavelengths (colors) in a periodic manner. By transmitting red, green, and blue colors sequentially rather than simultaneously, the system eliminates chromatic dispersion artifacts while maintaining compact electro-optic design, as each wavelength is steered independently at different time intervals.
Solution Approach 2:
The patent dynamically adjusts the liquid crystal grating's phase retardation in real-time to match the sequential color transmission timing. This dynamic control ensures that each color is steered to the correct retinal location at the moment of transmission, eliminating optical artifacts while preserving device compactness.
3Object-generated harmful factors
If sequential color transmission is implemented, then chromatic dispersion is reduced, but transmission time increases
Solution Approach 1:
The patent pre-calculates and stores the optimal phase retardation values for each wavelength in a lookup table. This preliminary preparation allows the system to rapidly switch between colors without computational delays, minimizing transmission time while effectively eliminating chromatic dispersion through precise sequential control.
Solution Approach 2:
The patent maintains continuous operation by seamlessly cycling through colors at high speed, ensuring that the sequential transmission is imperceptible to users. The continuous updating of phase retardation values keeps the beam steering effective throughout the color cycling process, minimizing perceived transmission time while eliminating chromatic artifacts.
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
The solution provides a compact, efficient, and user-friendly display device with improved field of view and reduced optical artifacts, enhancing the virtual and augmented reality experience.
Implementation Method 1
A beam steering device includes a liquid crystal grating having a phase retardation that is adjustable by applying a voltage between a pair of electrodes of the liquid crystal grating
Implementation Method 2
A beam steering device includes a liquid crystal grating having a phase retardation that is adjustable by applying a voltage between a pair of electrodes of the liquid crystal grating
Data Source
AI summary
A method includes sequentially transmitting, through a beam steering device, light of a first color and light of a second color that is distinct from the first color. The method also includes applying a first voltage to the beam steering device for transmission of the light of the first color through the beam steering device; and applying a second voltage to the beam steering device for transmission of the light of the second color through the beam steering device. A device configured to perform the method is also described.