Diffractive Filtering in Waveguide Displays for Image Uniformity
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Solution Overview
Problem
Waveguide display systems face issues with image nonuniformities and ghost images due to undesired color bands being coupled into waveguides, which existing absorptive and reflective filters fail to adequately address, leading to inefficiencies and increased power consumption.
Innovation Solution
The implementation of diffractive filtering between waveguides to selectively diffract out-of-band wavelengths, preventing them from being coupled into wavelength-band-specific waveguides, thereby avoiding nonuniformities and ghost images.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If absorptive or reflective filters are used to block out-of-band wavelengths, then image uniformity is improved, but optical losses increase and power consumption increases
Solution Approach 1:
The patent replaces absorptive and reflective filters with diffractive optical elements (gratings) that use diffraction to redirect out-of-band wavelengths. This substitution eliminates the need for absorption or reflection mechanisms, reducing optical losses while maintaining image uniformity through wavelength-selective diffraction into waveguides.
2Manufacturing precision
If absorptive or reflective filters are used to block out-of-band wavelengths, then image uniformity is improved, but device complexity increases
Solution Approach 1:
The patent merges the filtering function with the waveguide input couplers by integrating diffractive optical elements directly into the waveguide structures. This consolidation eliminates separate filter components and reduces overall device complexity while maintaining wavelength-selective functionality for image uniformity.
3Manufacturing precision
If multiple waveguides are used to deliver different color subframes, then color image quality is improved, but susceptibility to nonuniformities and ghost images increases
Solution Approach 1:
The patent introduces diffractive optical elements as intermediary components between the light source and multiple waveguides. These elements act as wavelength-selective mediators that direct specific wavelength bands into appropriate waveguides, preventing cross-contamination of wavelength bands that causes nonuniformities and ghost images while maintaining color image quality.
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
Diffractive filtering effectively limits out-of-band wavelengths from entering intended waveguides, enhancing image uniformity and reducing optical losses, thus improving the overall performance of waveguide display systems.
Implementation Method 1
a diffractive filter positioned optically between the first waveguide and the second waveguide, the diffractive filter being configured to diffract light of the first wavelength band and transmit light of the second wavelength band
Data Source
AI summary
Examples are disclosed that relate to the use of diffractive filtering in a waveguide display system. One example provides a display system including a light source, a first waveguide configured to conduct light of a first wavelength band from the light source, the first waveguide comprising a first input coupler, a second waveguide configured to conduct light of a second wavelength band from the light source, the second waveguide comprising a second input coupler, and a diffractive filter positioned optically between the first waveguide and the second waveguide, the diffractive filter being configured to diffract light of the first wavelength band and transmit light of the second wavelength band.