Waveguide Polarization Structure for Uniform Holographic Display Light
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Solution Overview
Problem
Existing holographic display technologies face challenges in achieving uniform light emission intensity and coherence in backlight units due to manufacturing difficulties in adjusting light extraction efficiency, which affects the quality of 3D image display.
Innovation Solution
A waveguide structure with multiple layers and gratings, including polarization separation and conversion elements, is designed to achieve uniform light extraction efficiency by varying transmission/reflection ratios across different areas, ensuring consistent light intensity output.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If light extraction efficiency is adjusted by varying output grating properties across different areas, then uniform light emission intensity is achieved, but manufacturing complexity increases
Solution Approach 1:
The patent applies local quality by varying the light extraction efficiency of the output grating across different areas of the waveguide. Specifically, the output grating is designed with different grating depths, periods, or orientations in different regions to compensate for the non-uniform light distribution, ensuring that the final emitted light has uniform intensity across the entire display area.
Solution Approach 2:
The patent implements parameter changes by modifying the physical parameters of the output grating (such as grating depth, period, duty cycle, or orientation angle) across different areas of the waveguide. These parameter variations are carefully controlled to adjust the local light extraction efficiency, transforming the non-uniform light distribution into a uniform output.
2Reliability
If high coherence light is used in holographic display backlight unit, then 3D image quality is improved, but light uniformity becomes difficult to achieve
Solution Approach 1:
The patent resolves this contradiction by applying local quality through spatially varying the output grating characteristics. The input grating maintains high coherence light from the laser source, while the output grating is locally optimized in different areas to extract light uniformly, thus preserving coherence while achieving uniformity.
Solution Approach 2:
The patent uses segmentation by dividing the output grating into multiple zones with different parameters. Each zone is independently optimized to extract light at the appropriate intensity level, allowing the system to maintain overall coherence while achieving local uniformity across the entire emission area.
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 waveguide structure ensures uniform light emission intensity, enhancing the quality of 3D image display by maintaining coherence and reducing manufacturing complexities.
Implementation Method 1
a first waveguide layer 110 and a second waveguide layer 120... for waveguiding light
Implementation Method 2
a first input grating 210, a second input grating 220, and a third input grating 230... provided on the waveguide layers
Implementation Method 3
an output grating 500... provided on the second waveguide layer 120
Implementation Method 4
a first polarization separation element 310... having different transmission/reflection ratios for each area
Implementation Method 5
a first polarization conversion element 410... provided on the first waveguide layer 110
Data Source
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AI summary
Provided is a waveguide structure (15) including an output grating (500), a polarization conversion element (410) provided parallel to the output grating (500), and a polarization separation element (310) provided between the output grating (500) and the polarization conversion element (410), wherein the polarization separation element (310) is configured to transmit, to the output grating (500), light (L1) having a first polarization direction among light incident on the polarization separation element (310), and reflect, to the polarization conversion element (410), light (L2) having a second polarization direction different from the light having the first polarization direction among the light incident on the polarization separation element (310). (Fig. 13)