Optical Waveguide Beam Splitter with Reflective Polarizers
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Solution Overview
Problem
Head-mounted display devices face challenges in providing uniform illumination to spatial light modulators, which is essential for high-quality images, especially in compact and lightweight designs.
Innovation Solution
The use of optical waveguides with reflective polarizers and polarization selective elements to redirect and transmit light in a controlled manner, ensuring uniform illumination of spatial light modulators within the display devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If compact-sized and light-weighted optical devices are used in head-mounted display devices, then device portability and user comfort are improved, but uniform illumination of spatial light modulators becomes challenging
Solution Approach 1:
The optical waveguide is divided into multiple segments with different extraction features at various positions. Each segment redirects a portion of the light to the spatial light modulator, enabling uniform illumination across the entire modulator surface while maintaining a compact waveguide structure that reduces overall device weight.
Solution Approach 2:
Different regions of the optical waveguide are equipped with extraction features having different optical properties tailored to local illumination requirements. This ensures that each area of the spatial light modulator receives appropriate light intensity, achieving uniform illumination without requiring a large, heavy optical system.
2Illumination intensity
If multiple reflective polarizers are disposed inside the optical waveguide to redirect light portions, then illumination uniformity is improved, but device complexity increases
Solution Approach 1:
Multiple reflective polarizers and extraction features are integrated into a single optical waveguide structure. This merging of components achieves uniform illumination through controlled light redirection while avoiding the complexity of separate optical assemblies, as all elements work together within one unified waveguide system.
Solution Approach 2:
The optical waveguide serves multiple functions simultaneously: it guides light from the source, contains multiple reflective polarizers for light redirection, and incorporates extraction features for controlled light extraction. This multi-functionality achieves uniform illumination without requiring additional separate components, thereby reducing overall device complexity.
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 approach enhances image quality and device efficiency by providing consistent illumination to spatial light modulators, improving the performance of head-mounted display devices in virtual, augmented, and mixed reality applications.
Implementation Method 1
The first reflective polarizer receives light propagating inside the optical waveguide, redirects a first portion of the light in a first direction
Implementation Method 2
The first reflective polarizer and the second reflective polarizer are disposed inside the optical waveguide so that the first reflective polarizer receives light propagating inside the optical waveguide
Implementation Method 3
A second portion, distinct from the first portion, of the light undergoes total internal reflection, thereby continuing to propagate inside the optical waveguide
Data Source
AI summary
An optical device includes an optical waveguide and a plurality of reflective polarizers. The plurality of reflective polarizers include a first reflective polarizer and a second reflective polarizer disposed inside the optical waveguide so that the first reflective polarizer receives light propagating inside the optical waveguide, redirects a first portion of the light in a first direction, and transmits a second portion of the light in a second direction non-parallel to the first direction. The second reflective polarizer receives the second portion of the light from the first reflective polarizer, redirects a third portion of the light, and transmits a fourth portion of the light. A ratio between the first portion and the second portion of the light has a first value and a ratio between the third portion and the fourth portion of the light has a second value distinct from the first value.