Diffractive Waveguide Optics for Uniform Exit Pupil Brightness
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Solution Overview
Problem
Existing optical apparatuses, such as exit pupil expanders, suffer from uneven brightness distribution in the exit pupil, leading to non-uniform image quality in display systems like near eye displays and virtual reality headsets.
Innovation Solution
The use of light guiding means with in-coupling and out-coupling diffractive elements, combined with varying diffraction efficiencies and configurations, to uniformly distribute light across the exit pupil.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If conventional exit pupil expanders are used, then the exit pupil size is increased, but the brightness distribution becomes uneven
Solution Approach 1:
The patent applies local quality by varying the diffraction efficiency of different regions of the diffractive optical element. Specifically, the diffractive optical element has a first region with a first diffraction efficiency and a second region with a second diffraction efficiency, where the efficiencies are different. This allows different portions of the exit pupil to have optimized brightness characteristics, compensating for the non-uniform illumination and achieving more uniform overall brightness distribution while maintaining the expanded exit pupil size.
2Device complexity
If diffractive elements with uniform diffraction efficiency are used, then the device structure is simple, but the brightness distribution in the exit pupil is non-uniform
Solution Approach 1:
The patent implements local quality by creating a diffractive optical element with spatially varying diffraction efficiency. The element is divided into at least two regions with different diffraction efficiencies, allowing each region to contribute differently to the overall brightness distribution. This approach maintains relative structural simplicity while achieving uniform brightness through localized property variations rather than complex multi-component designs.
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
This configuration achieves a more uniform brightness distribution in the exit pupil, enhancing image quality and reducing bright corners or dark regions, thereby improving the overall display performance.
Implementation Method 1
The light guiding means comprises an in-coupling diffractive means, an expanding means and an out-coupling diffractive means
Data Source
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AI summary
Examples of the disclosure relate to optical apparatus, modules and devices. Examples of the disclosure relate to an apparatus comprising a light guiding means. The light guiding means comprises at least; in-coupling diffractive means configured to in-couple one or more input beams of light into the light guiding means from a light engine, expanding means configured to expand the one or more input beams of light, and out-coupling diffractive means configured to out-couple the one or more expanded beams of light from the light guiding means. The out-coupling diffractive means comprises at least a first section configured to out-couple the one or more expanded beams of light with a first efficiency and at least a second section configured to out-couple the one or more expanded beams of light with a second efficiency, where the second efficiency is lower than the first efficiency.