Near-Eye Display SLM for Reduced Waveguide Interference
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Solution Overview
Problem
Near-eye display devices face challenges with large LED modules that result in a bulky product due to the need for a wide field of view and high resolution, and laser-based light sources cause undesirable interference within the waveguide due to their high spatial coherence, affecting image quality.
Innovation Solution
Incorporating a spatial light modulator (SLM) to reduce the spatial coherence of laser light rays before they enter the waveguide, and using optical structures within the waveguide to minimize interference, such as anti-reflection coatings or polarization-changing elements, to ensure non-coherent light propagation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If large LED modules are used to achieve wide field of view and high resolution, then image quality is improved, but device size and weight increase making the product bulky
Solution Approach 1:
The patent replaces the mechanical/optical system using large LED modules with a laser-based system. Lasers provide coherent light that can be efficiently coupled into waveguides, achieving wide field of view and high resolution without requiring large light source modules. This substitution of the light generation mechanism resolves the contradiction between image quality and device size/weight.
Solution Approach 2:
The patent transitions from using large lateral LED modules to using compact laser sources combined with waveguide optics that expand the beam in controlled dimensions. The waveguide structure enables light propagation and image formation in a different spatial configuration, achieving wide field of view through optical path design rather than large source size.
2Weight of stationary object
If laser-based light sources are used to reduce device size, then device compactness is improved, but spatial coherence causes interference within the waveguide affecting image quality
Solution Approach 1:
The patent introduces an intermediary element (such as a diffuser, scattering medium, or specialized optical component) within the waveguide system to reduce the spatial coherence of the laser light. This intermediary breaks up the coherent light paths that cause interference while maintaining the compact laser source, thus resolving the contradiction between device compactness and image quality.
Solution Approach 2:
The patent modifies the coherence parameter of the laser light by introducing optical elements that alter the light's spatial coherence properties. By changing the coherence parameter from high (causing interference) to reduced levels (minimizing interference), the system maintains compactness while improving image quality.
3Manufacturing precision
If spatial coherence of laser light is reduced using SLM and optical structures, then interference is minimized improving image quality, but device complexity increases
Solution Approach 1:
The patent integrates the spatial light modulator and optical structures into multi-functional components that serve both coherence reduction and other system functions (such as beam shaping, steering, or modulation). By making components multi-functional, the patent reduces overall device complexity while maintaining image quality improvements.
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 NED device with improved image quality by reducing interference and maintaining a wide field of view without the bulkiness associated with large LED modules.
Implementation Method 1
Incorporating a spatial light modulator (SLM) to reduce the spatial coherence of laser light rays before they enter the waveguide
Implementation Method 2
Waveguides may be used in an NED device to convey light representing artificially-generated images from the image generation components of the device to an optical receptor of a user
Implementation Method 3
using optical structures within the waveguide to minimize interference, such as anti-reflection coatings or polarization-changing elements
Implementation Method 4
using optical structures within the waveguide to minimize interference, such as anti-reflection coatings or polarization-changing elements
Data Source
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AI summary
Disclosed are an apparatus and method for reducing interference for a near-eye display device. The near-eye display device includes an imager, a spatial light modulator and a waveguide. The imager generates an image based on light from a coherent light source. The spatial light modulator modulates phases of a plurality of coherent light rays representing the image received from the imager. The waveguide receives and guides the light rays having varied phases such that light rays propagating within the waveguide are incoherent with each other.