DOE Brightness Uniformity Tuning for HMD Vignetting
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Head-mounted display (HMD) devices face challenges in producing consistently high-quality, realistic images due to difficulties in optimizing spatial uniformity of brightness, often resulting in vignetting where image edges appear dimmer than the center, which undermines the visualization experience.
Innovation Solution
Incorporating a diffractive optical element (DOE) with diffraction gratings and total internal reflection characteristics into the optical path of HMD devices, where light exiting the DOE's peripheral region is brighter than the central region, to address brightness non-uniformities without affecting exit pupil size or consuming input data bits for brightness compensation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If conventional optics are used in HMD devices, then the device structure is simple, but the brightness uniformity deteriorates with vignetting at image edges
Solution Approach 1:
The patent applies local quality by creating different optical characteristics in different regions of the waveguide. Specifically, the waveguide has a first region with a first refractive index and a second region with a second refractive index, where the refractive indices differ to control light propagation differently in each region. This allows the peripheral regions to receive more light energy than the central region, compensating for vignetting and achieving uniform brightness across the display without adding complex external optical components.
2Illumination intensity
If brightness compensation is attempted through software or additional optics, then brightness uniformity may improve, but device complexity or data processing requirements increase
Solution Approach 1:
The patent replaces complex mechanical or software-based brightness compensation systems with an optically integrated solution. Instead of using additional optical components or software processing to compensate for vignetting, the invention embeds the brightness uniformity correction directly into the waveguide structure through region-specific refractive index modulation. This optical substitution eliminates the need for separate compensation mechanisms while achieving the desired brightness uniformity.
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 DOE effectively enhances brightness uniformity across the displayed image, improving the realism and quality of the visualization experience by making the edges of the image appear brighter, thus correcting vignetting and other brightness non-uniformities.
Implementation Method 1
a diffractive optical element (DOE) that is optically coupled to receive light from the light emitter and to convey the light along an optical path
Implementation Method 2
Incorporating a diffractive optical element (DOE) with diffraction gratings and total internal reflection characteristics into the optical path
Data Source
AI summary
Introduced here is a display device that comprises a light emitter and a diffractive optical element (DOE) that is optically coupled to receive light from the light emitter and to convey the light along an optical path. The DOE may have an input surface and an output surface parallel to the input surface, where the input surface and the output surface each have a central region and a peripheral region. The DOE further may have optical characteristics such that light exiting the DOE in the peripheral region of the output surface has greater brightness than light exiting the DOE in the central region of the output surface.