Liquid Crystal Layer-Set Filter for Narrowband Light Selection
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Solution Overview
Problem
Existing band-pass filters lack versatility and efficiency in selectively transmitting light in a specific wavelength range while blocking other ranges, particularly in optical devices.
Innovation Solution
A novel filter configuration comprising three or more liquid crystal layer sets, each formed by twisted and aligned liquid crystal compounds with opposite twisted directions, and polarizers disposed in crossed nicols, where the twisted angles and Δnd values are carefully controlled to achieve a λ/2 retardation effect only for a specific wavelength range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional band-pass filters (polarization interference filters, birefringent crystal filters) are used, then light transmission in specific wavelength ranges is achieved, but the filters lack versatility and efficiency in selective transmission
Solution Approach 1:
The filter is divided into multiple liquid crystal layer sets (three or more) stacked in the thickness direction. Each layer set contains first and second liquid crystal layers with opposite twisted directions, allowing independent control of optical properties for each layer. This segmentation enables versatile wavelength selection while maintaining high transmission efficiency through cumulative retardation effects.
Solution Approach 2:
The patent utilizes changes in liquid crystal molecule orientation (twisted direction and twisted angle) to control optical properties. By adjusting the twisted angle (e.g., 45 degrees) and stacking multiple layers with opposite twists, the filter achieves wavelength-selective transmission. The parameter Δnd (birefringence × thickness) is carefully controlled to produce λ/2 retardation for specific wavelengths, enabling both versatility and efficiency.
2Measurement precision
If multiple liquid crystal layers with opposite twisted directions are stacked, then precise spectral control is achieved, but the device complexity increases
Solution Approach 1:
Multiple liquid crystal layers with opposite twisted directions are combined into integrated layer sets. Each layer set functions as a unified optical element where the first and second layers work together to produce the desired λ/2 retardation effect. This merging approach achieves precise spectral control while managing complexity through functional integration rather than treating each layer as separate components.
Solution Approach 2:
The filter employs composite liquid crystal structures where layers with different twisted directions are combined. The first liquid crystal layer and second liquid crystal layer form a composite system with complementary optical properties. This composite approach enables precise wavelength selection through interference effects while the overall structure remains manageable through systematic design of layer thickness and orientation.
3Manufacturing precision
If the filter structure uses three or more liquid crystal layer sets with specific twisted angles, then narrow wavelength range transmission is achieved, but the manufacturing precision requirements increase
Solution Approach 1:
The liquid crystal layers are pre-aligned during manufacturing to achieve specific twisted angles (e.g., 45 degrees) and opposite twisted directions. Alignment films or surface treatments are applied beforehand to guide liquid crystal molecule orientation. This preliminary alignment action ensures that the critical parameters for narrow wavelength selection are established during fabrication, reducing the need for post-manufacturing adjustment while achieving high manufacturing precision.
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 filter effectively transmits light in a narrow wavelength range and blocks other wavelengths, allowing for precise spectral control and improved performance in optical devices.
Implementation Method 1
a first liquid crystal layer formed by fixing the liquid crystal compound twisted and aligned in the thickness direction, and a second liquid crystal layer formed by fixing the liquid crystal compound twisted and aligned in the thickness direction
Implementation Method 2
a twisted angle of the liquid crystal compound in the first liquid crystal layer and a twisted angle of the liquid crystal compound in the second liquid crystal layer are equal
Implementation Method 3
polarizers between which the three or more liquid crystal layer sets are interposed in the thickness direction, in which the polarizers between which the three or more liquid crystal layer sets are interposed in the thickness direction are disposed so that transmission axes of the polarizers are orthogonal to each other
Data Source
AI summary
An object of the present invention is to provide a novel filter that is used as a band-pass filter or the like. To achieve the object, three or more liquid crystal layer sets, each consisting of a first liquid crystal layer formed by twisting, aligning, and fixing a liquid crystal compound and a second liquid crystal layer in which a twisted direction of a liquid crystal compound is opposite to that in the first liquid crystal layer, are provided, alignment directions of the liquid crystal compound are parallel to each other at an interface between the first liquid crystal layer and the second liquid crystal layer, and a twisted angle of the liquid crystal compound in the first liquid crystal layer and a twisted angle of the liquid crystal compound in the second liquid crystal layer are equal.