Optical Display System Using Diffractive Liquid Crystal Lenses
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Solution Overview
Problem
Conventional Maxwellian-view displays face challenges with small eyebox size, poor image quality, and reduced optical efficiency due to the vergence-accommodation conflict, and existing solutions like pupil duplication and steering methods either compromise image clarity or increase system complexity.
Innovation Solution
An optical display system incorporating a controllable optical image-generating apparatus, a beam scanning unit, an exit pupil steering apparatus with diffractive liquid crystal lenses, and an eye-tracking apparatus to adjust the direction of circularly polarized image output based on viewer position, ensuring high optical efficiency and improved image quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If pupil duplication methods using holographic gratings are applied to enlarge eyebox, then the eyebox size is increased, but the optical efficiency drops to 1/N and image clarity deteriorates due to ghost images and mismatched chief rays
Solution Approach 1:
The patent employs a liquid crystal display (LCOS) modulator that dynamically modulates the phase of incident light based on real-time eye tracking data. This dynamic phase modulation enables the system to steer the exit pupil to different positions on demand, rather than having multiple fixed viewing points simultaneously present as in holographic grating approaches. The dynamic control maintains high optical efficiency by directing all light to the correct viewing position.
Solution Approach 2:
The system incorporates an eye tracking apparatus that provides real-time feedback on the user's eye position. This feedback is used by the LCOS modulator to adjust the phase of light dynamically, ensuring the exit pupil is always steered to the correct position corresponding to the user's actual viewing location. This closed-loop feedback mechanism eliminates the chief ray mismatch problem and maintains optimal optical efficiency.
2Device complexity
If conventional lens coupler is used in pupil steering system, then the system structure is simplified, but image quality deteriorates significantly because the lens coupler can achieve diffraction limits only at one incident angle
Solution Approach 1:
The patent replaces the conventional lens coupler with a liquid crystal on silicon (LCOS) modulator that uses electro-optic phase modulation to steer the exit pupil. This substitution eliminates the need for mechanical moving parts while achieving superior image quality through dynamic phase control. The LCOS modulator can adjust the phase of light waves to precisely control the direction of the exit pupil without the angular limitations of fixed lens couplers.
Solution Approach 2:
The system changes the optical parameters dynamically by using the LCOS modulator to modulate the phase of incident light according to different viewing positions. By adjusting the phase parameter in real-time based on eye tracking feedback, the system maintains high image quality across multiple viewing positions without requiring mechanical adjustments or multiple fixed optical paths.
3Measurement precision
If mechanical shifting parts are added to correct chief ray mismatch in pupil steering system, then the viewing direction accuracy is improved, but the system complexity and weight increase
Solution Approach 1:
The patent eliminates mechanical shifting parts by using an LCOS modulator that achieves viewing direction adjustment through electro-optic phase modulation. The LCOS device controls the phase of light waves to steer the exit pupil to different positions without any mechanical moving parts, thereby maintaining viewing direction accuracy while avoiding the complexity and weight of mechanical systems.
Solution Approach 2:
Instead of mechanically shifting optical components to correct chief ray mismatch, the system changes the phase parameter of light using the LCOS modulator. This parameter change approach allows dynamic adjustment of the exit pupil position and viewing direction through electrical control, eliminating the need for mechanical shifting parts while maintaining precision.
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 system achieves an expanded eyebox, natural viewing experience, and high optical efficiency while maintaining a simple and lightweight design by directing the image output to the correct diffractive liquid crystal lens, minimizing optical aberrations and matching the chief ray with the viewing direction.
Implementation Method 1
an exit pupil steering apparatus, including diffractive liquid crystal lenses, wherein each diffractive liquid crystal lens focuses the circularly polarized image output of one circular polarization state to a distinct focus point
Implementation Method 2
a controllable optical image-generating display apparatus, which generates circularly polarized image output
Data Source
AI summary
An optical display system and an electronic device are disclosed. The optical display system comprises: a controllable optical image-generating display apparatus, generating circularly polarized image output; a beam scanning unit, adjusting a direction of the circularly polarized image output; an exit pupil steering apparatus, including diffractive liquid crystal lenses, each of which focuses the circularly polarized image output of one circular polarization state to a distinct focus point and let light with the other circular polarization state pass directly through; and an eye-tracking apparatus, detecting position information of a viewer's eye pupil and providing the position information to the beam scanning unit. The beam scanning unit adjusts the direction of the circularly polarized image output according to the position information, so that the circularly polarized image output is diffracted by one of the diffractive liquid crystal lenses.