Segmented Polarization Grating for High-Speed Beam Deflection
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Solution Overview
Problem
Conventional polarization gratings fail to simultaneously and independently deflect multiple optical beams with various wavelengths through a wide angle at high speed and are unstable at ambient temperatures, making them unsuitable for advanced autonomous driving applications.
Innovation Solution
The optical beam deflection element employs a half-wave phase plate and polarization grating plate with a polymer-stabilized blue phase liquid crystal, featuring segmented thin-film electrodes and a hermetically sealed structure with temperature control, allowing for high-speed switching and operation across various angular ranges and wavelengths.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional polarization gratings are used for beam deflection, then the device structure is simple, but the deflection angle is limited and multiple beams cannot be independently deflected
Solution Approach 1:
The polarization grating plate is divided into multiple independent segments, each capable of independently deflecting optical beams. This segmentation allows multiple beams to be deflected independently while maintaining a relatively simple overall device structure, resolving the contradiction between adaptability and device complexity.
Solution Approach 2:
The invention uses liquid crystal materials that can dynamically change their optical properties when voltage is applied. This dynamic characteristic enables the polarization grating to adjust its deflection angle and switch between different beam paths, providing independent deflection capability for multiple beams without requiring complex mechanical moving parts.
2Speed
If conventional nematic liquid crystal is used for high-speed switching, then the device structure is simple, but the switching speed is insufficient for μ-second operation
Solution Approach 1:
The invention changes the material parameter from conventional nematic liquid crystal to blue phase liquid crystal, which has inherently faster response characteristics. This material parameter change enables μ-second switching speed while maintaining a relatively simple device structure without requiring additional complex components.
Solution Approach 2:
The invention uses composite material structures including blue phase liquid crystal combined with polymer stabilization and specific electrode configurations. This composite approach achieves fast switching speeds through material properties while keeping the overall device structure manageable through integrated design.
3Reliability
If liquid crystal materials are used without temperature control, then the device structure is simple, but the performance becomes unstable at ambient temperatures
Solution Approach 1:
The invention applies polymer stabilization locally within the liquid crystal material to improve temperature stability. This local quality enhancement provides reliable performance across ambient temperatures while avoiding the need for complex external temperature control systems, thus maintaining device structure simplicity.
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 enables rapid, reliable deflection of multiple optical beams with various wavelengths across wide angles, maintaining stability at ambient temperatures, thus addressing the limitations of conventional systems for advanced autonomous driving and multi-laser radar applications.
Implementation Method 1
a birefringent medium in which a birefringence axis spatially rotates with a constant period
Implementation Method 2
a half-wave phase plate and a polarization grating plate with a polymer-stabilized blue phase liquid crystal
Data Source
Figure 1
Figure 2
Figure 3(A)~3(B)
AI summary
With the conventional optical deflection elements using polarization gratings (PGs), it has been difficult to independently switch multiple optical beams at one time in a variety of angular ranges and angular steps at high speed on the µ-second time scale, and it has been impossible to achieve a highly reliable optical deflection element module capable of operating at different ambient temperatures. Provided is an optical deflection element including: a polarization grating plate having a rectangular or circular segment structure, in which the cycles A of PGs are not uniform within the plate plane and the cycle and/or the rotational direction of a birefringence axis varies; and a phase panel having a segment structure that is accordingly segmented within the same plane are bonded together, wherein their corresponding segments overlap with each other, and optical switches of the polarization gratings are controlled by a voltage change in the phase panel.