Exposure Device Polarization Rotation for Alignment Accuracy
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Solution Overview
Problem
Existing exposure methods for forming photo-alignment films and optically-anisotropic layers face challenges in achieving high pattern accuracy, particularly with small arc patterns, due to undulation and positioning errors related to the scanning stage's resolution and straightness.
Innovation Solution
An exposure method and device that focus linearly polarized light in a ring shape using an optical member, such as an axicon lens, while rotating the polarization direction and moving the film and optical member in a tilted direction relative to the optical axis, ensuring precise alignment and pattern formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If a scanning stage is used to scan the spot in at least two dimensions along the surface of the polarization-sensitive recording medium, then the alignment pattern can be formed across the entire medium, but the pattern accuracy decreases for small arc patterns due to undulation caused by scanning stage resolution and straightness limitations
Solution Approach 1:
The patent replaces the mechanical scanning stage system with an optical field modulation system. Instead of physically moving the spot across the recording medium using a scanning stage, the invention modulates the polarization state of light across different spatial positions and temporal sequences, achieving pattern formation through optical field control rather than mechanical displacement. This substitution eliminates undulation errors inherent in mechanical scanning systems.
Solution Approach 2:
The patent introduces dynamic polarization control where the polarization state of light is continuously varied in time to encode different spatial positions and pattern information. The polarization selector stage dynamically switches between different polarization states, and the liquid crystal layer's orientation is dynamically adjusted, allowing the same optical path to form different parts of the alignment pattern through temporal modulation rather than mechanical movement.
2Adaptability or versatility
If the polarization selector stage and scanning stage are configured to perform polarization variation and scanning independently, then the system flexibility is improved, but the coordination complexity and positioning accuracy for small features deteriorate
Solution Approach 1:
The patent merges the functions of polarization selection and spatial positioning into a unified optical field modulation system. The polarization selector stage is integrated with the liquid crystal layer and optical paths such that polarization state control and spatial pattern formation are coupled rather than independent. This integration ensures that polarization variations automatically correspond to correct spatial positions without requiring complex coordination between separate scanning and polarization control systems.
Solution Approach 2:
The patent introduces the liquid crystal layer as an intermediary element that mediates between the polarization selector stage and the recording medium. The liquid crystal layer translates polarization state variations into spatially-resolved orientation patterns, acting as a mediator that converts temporal polarization modulation into spatial pattern information. This intermediary function eliminates the need for direct mechanical scanning while maintaining precise spatial control.
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 the accuracy of alignment patterns in photo-alignment films, allowing for the formation of high-precision optically-anisotropic layers with improved stability and uniformity, suitable for applications in liquid crystal displays and other optical elements.
Implementation Method 1
focusing linearly polarized light in a ring shape with an optical member
Implementation Method 2
exposing a film including a compound having a photo-aligned group
Data Source
AI summary
An object is to provide an exposure method and an exposure device for obtaining a photo-alignment film where the accuracy of an alignment pattern is high, and a method of forming an optically-anisotropic layer. In a case where linearly polarized light is focused in a ring shape with an optical member and a film including a compound having a photo-aligned group is exposed, while rotating a polarization direction of the polarized light, the film and the optical member are relatively moved in a direction tilted with respect to an optical axis of the optical member.