Liquid Crystal Reflective Polarizer with Elliptical Light Conversion
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Solution Overview
Problem
Cholesteric liquid crystal (CLC) reflective polarizers experience light leakage due to depolarization, which degrades the extinction ratio and increases as the incidence angle increases, especially when used in applications like virtual reality devices where low light leakage is crucial.
Innovation Solution
The optical device includes a first optical element that converts incident light into elliptically polarized light with specific polarization ellipse parameters, which is then reflected as circularly polarized light by a second optical element with a birefringent material, reducing light leakage by optimizing the ellipticity and orientation angle of the incident light to match the CLC layer properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a CLC reflective polarizer is used to reflect circularly polarized light, then the polarization selectivity is improved, but light leakage occurs due to depolarization which degrades the extinction ratio
Solution Approach 1:
The patent applies preliminary action by converting incident linearly polarized light into elliptically polarized light with optimized parameters before the light reaches the CLC reflective polarizer. This pre-conditioning of the light's polarization state ensures that when the light interacts with the CLC layer, the depolarization effect is minimized and light leakage is reduced to below 0.05%, thereby improving the extinction ratio while maintaining high polarization selectivity
2Adaptability or versatility
If the incidence angle increases, then the field of view is expanded, but light leakage increases which degrades the extinction ratio
Solution Approach 1:
The patent applies parameter changes by optimizing the ellipticity and orientation angle parameters of the incident elliptically polarized light to match the specific properties of the CLC layer (such as helical pitch and birefringence). This parameter optimization creates a robust system where light leakage remains below 0.05% across various incidence angles, allowing the device to maintain high extinction ratios even when the field of view is expanded through increased incidence angle ranges
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 significantly reduces light leakage to below 0.05%, improving the optical performance of CLC reflective polarizers by minimizing light transmittance and maintaining low leakage across various incidence angles.
Implementation Method 1
a first optical element configured to output an elliptically polarized light having one or more predetermined polarization ellipse parameters
Implementation Method 2
a second optical element including a birefringent material with a chirality. The second optical element is configured to receive the elliptically polarized light from the first optical element and reflect the elliptically polarized light as a circularly polarized light
Implementation Method 3
birefringent material with a chirality
Data Source
AI summary
An optical device is provided. The optical device includes a first optical element configured to output an elliptically polarized light having one or more predetermined polarization ellipse parameters. The optical device also includes a second optical element including a birefringent material with a chirality, and configured to receive the elliptically polarized light from the first optical element and reflect the elliptically polarized light as a circularly polarized light.