LCOS Illumination Lightguide with Polarization-Selective Facets
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Solution Overview
Problem
Conventional optical illumination systems are inefficient in providing uniform illumination, leading to non-uniform image intensity and increased cost, weight, and complexity due to the use of polarizing beam splitters.
Innovation Solution
A compact optical system utilizing a lightguide with parallel, partially reflecting, and polarization-selective facets at an oblique angle, combined with a front-lit reflective polarization rotating image modulator, to spatially modulate light and achieve uniform illumination, reducing the need for polarizing beam splitters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a polarizing beam splitter is used to illuminate the LCOS matrix, then the system can achieve polarized light illumination, but the system complexity, cost, and weight increase
Solution Approach 1:
The patent extracts and removes the polarizing beam splitter from the optical path by using a lightguide with polarization-selective facets that directly couple polarized light to the LCOS matrix, eliminating the need for the PBS and reducing system complexity
Solution Approach 2:
The lightguide with polarization-selective facets serves multiple functions: it guides light, provides polarization selection, and enables direct coupling to the LCOS matrix, replacing what would traditionally require separate components including a PBS
2Illumination intensity
If a polarizing beam splitter is used to illuminate the LCOS matrix, then the system can achieve polarized light illumination, but the cost and weight increase
Solution Approach 1:
The patent extracts and removes the polarizing beam splitter from the optical path by using a lightguide with polarization-selective facets that directly couple polarized light to the LCOS matrix, eliminating the need for the PBS and reducing system complexity
Solution Approach 2:
The patent merges the lightguide, polarization selection, and light coupling functions into a single integrated structure, eliminating the need for separate PBS components and reducing overall system weight
3Device complexity
If conventional illumination methods are used, then the system structure is simpler, but the illumination uniformity across the image light provider is non-uniform
Solution Approach 1:
The patent applies local quality by varying the facet properties (such as reflectivity or orientation) across different regions of the lightguide to compensate for non-uniform light distribution, ensuring uniform illumination across the entire LCOS matrix surface
4Device complexity
If a lightguide with polarization-selective facets is used, then the system achieves compact size and reduced complexity, but the manufacturing precision requirements increase
Solution Approach 1:
The patent employs parameter changes by systematically varying facet parameters (such as reflectivity, orientation, or spacing) to achieve uniform illumination while maintaining manufacturability through established fabrication techniques
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 system achieves uniform illumination across the image light provider, reducing non-uniformities and system complexity, while being more compact and cost-effective compared to conventional implementations.
Implementation Method 1
a first sequence of facets, at least a portion of which are: a plurality of parallel, partially reflecting, and polarization selective surfaces
Implementation Method 2
the first sequence of facets expands light in-coupled to the lightguide such that the light is uniformly coupled-out of the first external surface
Implementation Method 3
a front-lit reflective polarization rotating image modulator: deployed to spatially modulate light coupled-out from the first external surface, outputting reflected light corresponding to an image
Data Source
Figure 1~2
Figure 3A~3B
Figure 3C~3D
AI summary
A system for uniform optical illumination of an image light provider in a smaller (compact) configuration than conventional implementations includes a lightguide having: a first external surface and a second external surface mutually parallel, and a first sequence of facets, at least a portion of which are: a plurality of parallel, partially reflecting, and polarization selective surfaces, at an oblique angle relative to the first and second external surfaces, and between the first and second external surfaces, and a front-lit reflective polarization rotating image modulator: deployed to spatially modulate light coupled-out from the first external surface, outputting reflected light corresponding to an image, and deployed such that the reflected light traverses the lightguide from the first external surface via the first sequence of facets to the second external surface.