Circular Polarizing Filter with Scattering Layer
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Solution Overview
Problem
Existing circular polarizing filters fail to achieve high circular polarizance and sensitivity in sensor systems due to alignment defects and foreign substances in cholesteric liquid crystal layers, even with high uniformity, and the use of cover glass reduces circular polarizance.
Innovation Solution
A circular polarizing filter with a reflected light-scattering cholesteric liquid crystal layer that has alignment defects and a specific configuration to reduce interface reflection, enhancing scattering properties for improved circular polarizance, including a layer with a cholesteric liquid crystalline phase and a light blocking layer to block unwanted wavelengths.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a cholesteric liquid crystal layer with high alignment uniformity is used, then the circular polarizing filter can be manufactured with high precision, but the circular polarizance is still reduced due to alignment defects and foreign substances
Solution Approach 1:
The patent intentionally introduces light-scattering particles into the cholesteric liquid crystal layer, converting the harmful effect of scattering (which normally reduces polarizance) into a beneficial effect. The light-scattering particles increase the path length of light through the layer, enhancing the selective reflection of circularly polarized light and improving circular polarizance despite the presence of alignment defects and foreign substances.
2Duration of action of stationary object
If cover glass is disposed on the transmitted light side to protect the filter, then the filter durability is improved, but the circular polarizance is reduced due to interface reflection
Solution Approach 1:
The patent introduces a light-scattering layer as an intermediary between the cholesteric liquid crystal layer and the cover glass. This intermediary layer reduces interface reflection by scattering light, thereby maintaining high circular polarizance while allowing the cover glass to provide mechanical protection and durability to the filter structure.
3Manufacturing precision
If the cholesteric liquid crystal layer is made highly uniform to reduce defects, then the manufacturing precision is improved, but the sensitivity in sensor systems is reduced
Solution Approach 1:
The patent converts the normally harmful light-scattering effect into a beneficial enhancement of sensor sensitivity. By incorporating light-scattering particles, the filter increases the interaction length of light with the cholesteric liquid crystal layer, thereby enhancing the selective reflection properties and improving the sensitivity of sensor systems that detect circularly polarized light.
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 solution significantly improves the circular polarizance and sensitivity of the filter, allowing for effective transmission and reflection of circularly polarized light, suitable for applications in sensor systems and plant cultivation.
Implementation Method 1
a layer which is uniformly aligned such that the helical axis of a cholesteric liquid crystalline phase formed of a cholesteric liquid crystal compound is perpendicular to a cell substrate or a surface of a support is generally known to function as a circularly-polarized light-selective polarizing filter
Implementation Method 2
the circularly-polarized light separating layer includes a reflected light-scattering circularly-polarized light separating layer
Data Source
AI summary
According to the invention, there is provided a circular polarizing filter for selectively transmitting circularly polarized light of any one sense of either right-handed circularly polarized light or left-handed circularly polarized light at a specific wavelength in which scattering transmittance/vertical transmittance when circularly polarized light of the sense of the specific wavelength enters from any one surface is less than scattering reflectance/regular reflectance when circularly polarized light of the other sense enters from the surface. The circular polarizing filter includes a circularly-polarized light separating layer, the circularly-polarized light separating layer includes a reflected light-scattering circularly-polarized light separating layer, and may further include a reflected light-non-scattering circularly-polarized light separating layer, the reflected light-scattering circularly-polarized light separating layer is composed of a layer having a cholesteric liquid crystalline phase fixed therein, and the reflected light-non-scattering circularly-polarized light separating layer is composed of a layer having a cholesteric liquid crystalline phase fixed therein, or a laminate including a linearly-polarized light separating layer and a λ/4 phase difference layer. The circular polarizing filter of the invention has a high circular polarizance, and a high-sensitivity sensor system can be provided using the circular polarizing filter of the invention.