Holographic Display Disparity Sensor for AR Headset Alignment
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Solution Overview
Problem
Vertical disparity between displays of artificial-reality glasses causes user discomfort, including increased eye strain, double vision, and reduced image sharpness, due to mechanical design constraints and binocular vision issues.
Innovation Solution
A display disparity sensor using holographic optical elements to couple non-focused light from display waveguides onto light detectors, which are rigidly mounted to the displays, allowing for the detection and correction of positional, angular, and optical disparities between the displays.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If mechanical design interventions are used to align displays, then display alignment can be improved, but device complexity and manufacturing constraints increase
Solution Approach 1:
The patent replaces mechanical alignment adjustments with an optical field-based measurement and correction system. Instead of using complex mechanical interventions to physically align displays, the system uses holographic optical elements to create focused light beams that enable precise measurement of display disparities through light detection, substituting mechanical complexity with optical field manipulation.
Solution Approach 2:
The patent introduces holographic optical elements and light detectors as intermediary components between the displays and the measurement system. These intermediaries transform the light fields from display waveguides into focused beams that carry disparity information, enabling indirect measurement of alignment without direct mechanical intervention on the displays themselves.
2Ease of operation
If display disparity is not corrected, then device complexity is reduced, but user comfort and visual quality deteriorate
Solution Approach 1:
The system performs self-calibration by automatically measuring display disparities using the holographic optical elements and light detectors, then using this measurement data to adjust the display content. The system serves itself by detecting its own alignment state and correcting disparities without requiring external intervention or complex manual calibration procedures.
Solution Approach 2:
The patent implements a feedback loop where light detectors measure the position of focused light spots from display waveguides, the measurement data is processed to determine display disparity, and this information is fed back to correct the displayed content. This continuous feedback mechanism ensures user comfort by automatically maintaining proper display alignment.
3Measurement precision
If light detection sensitivity is increased to measure small disparities, then measurement precision improves, but device complexity and cost increase
Solution Approach 1:
The patent uses holographic optical elements that transform planar light waves into focused spherical light beams. This curvature transformation concentrates the light energy into a tight focal spot, enhancing the signal intensity and measurement precision without requiring proportionally more complex or expensive sensors. The spherical focusing naturally amplifies the spatial frequency information needed for precise disparity measurement.
Solution Approach 2:
The system changes the optical parameters of the light field by using holographic elements to transform the wavefront curvature and spatial distribution. This parameter transformation concentrates the light into a focused beam with enhanced spatial frequency content, allowing standard light detectors to achieve high measurement precision through optimized optical parameter manipulation rather than more complex sensing hardware.
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 effectively reduces display artifacts such as image misalignment and double vision by calibrating images based on disparity measurements, ensuring alignment within specified tolerances and enhancing user comfort and experience.
Implementation Method 1
each holographic optical element is configured to transform planar electromagnetic waves received from a corresponding display waveguide into a focused light beam that is incident onto the respective light detector
Implementation Method 2
each holographic optical element focuses the light received from a corresponding output coupler and onto a corresponding light detector to generate display disparity calibration data
Data Source
AI summary
An artificial-reality (AR) headset including a first holographic element that projects first focused light onto a first light detector and a second holographic element that projects second focused light onto a second light detector. The AR headset includes a first display coupled to the first holographic element, wherein the first display causes display of a first image, and a second display coupled to the second holographic element, where the second display causes display of a second image. The headset includes at least one display engine configured to receive respective calibration data from the first light detector and the second light detector; determine, based on comparing the respective calibration data, a disparity between the first display and the second display; and in accordance with a determination that the disparity between the first display and the second display satisfies disparity correction criteria generate an updated first image or updated second image.