Multispectral Filter Layout for Uniform Tint and Low Crosstalk
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Solution Overview
Problem
Existing multispectral imaging apparatuses face issues with light leakage and interference (crosstalk) due to incomplete beam separation using microlens arrays, leading to non-uniform image tints and requiring significant effort to quantify interference levels across pixels.
Innovation Solution
A filter comprising an optical filter layer with at least three reflective layers made of cholesteric liquid crystal layers having different reflection center wavelengths, combined with a patterned retardation layer having a slow axis direction corresponding to the reflection center wavelengths, which reduces interference and enhances image quality by providing a uniform tint in multispectral images.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If beam separation is performed using a microlens array, then multispectral image acquisition is enabled, but light leakage and interference (crosstalk) occur between adjacent pixels
Solution Approach 1:
The filter is divided into multiple wavelength-selective regions, each containing reflective layers with specific reflection center wavelengths. This segmentation allows different wavelength ranges to be directed to different pixel groups, achieving spectral separation without requiring complete beam separation by microlens array
Solution Approach 2:
Different regions of the filter have different optical characteristics tailored to specific wavelength ranges. The reflective layers are strategically positioned and configured with different reflection center wavelengths (e.g., first reflective layer for blue-green range, second for green-yellow range, third for red range) to optimize performance for each spectral band
2Reliability
If signal processing is performed to remove interference influence, then image quality can be improved, but a huge amount of effort is required to obtain interference amounts for each pixel
Solution Approach 1:
The filter structure is designed to minimize interference at the optical level before detection. By using reflective layers with specific reflection center wavelengths and configuring their positions and thicknesses, the filter pre-separates wavelength ranges and reduces crosstalk, eliminating the need for complex post-processing to quantify and correct interference
Solution Approach 2:
The patent converts the potential harmful effect of partial beam separation into a beneficial outcome by designing reflective layers that actively manage light distribution. The reflective layers reflect specific wavelength ranges to appropriate pixel groups, transforming what could be interference into organized spectral separation that enhances image quality
3Stability of the object's composition
If non-uniform interference occurs across pixels, then image tint becomes non-uniform, but achieving uniform tint requires obtaining interference amounts for each pixel position
Solution Approach 1:
The filter is designed with spatially varying optical properties to compensate for position-dependent interference. Reflective layers are strategically positioned at different locations with different reflection center wavelengths and thicknesses, creating local optimizations that ensure uniform image tint across all pixel positions without requiring complex measurement and correction
Solution Approach 2:
The patent varies key parameters of the reflective layers including reflection center wavelengths, layer thicknesses, and positional arrangements to optimize performance. By adjusting these parameters across different regions of the filter, the design achieves uniform image tint while minimizing interference, eliminating the need for complex measurement and correction procedures
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 effectively minimizes light interference and achieves a higher-quality multispectral image with uniform tints by aligning the retardation layer's slow axis with the reflective layers' wavelengths, improving detection accuracy and image quality.
Implementation Method 1
the reflective layers have different reflection center wavelengths
Implementation Method 2
an optical filter layer 20; and a patterned retardation layer 22 that is laminated on the optical filter layer 20, in which the optical filter layer includes at least three reflective layers that are formed of a cholesteric liquid crystal layer, the reflective layers have different reflection center wavelengths
Implementation Method 3
the patterned retardation layer has a slow axis in a direction corresponding to the reflection center wavelength of the reflective layer
Data Source
AI summary
Provided a filter and an imaging apparatus for obtaining a higher-quality multispectral image in which the tint of the image is uniform. The filter includes: an optical filter layer; and a patterned retardation layer that is laminated on the optical filter layer. The optical filter layer includes at least three reflective layers that are formed of a cholesteric liquid crystal layer, and the reflective layers have different reflection center wavelengths. Alternatively, the optical filter layer includes a reflective layer that is formed of a cholesteric liquid crystal layer having at least two different reflection center wavelengths. The patterned retardation layer has a slow axis in a direction corresponding to the reflection center wavelength of the reflective layer.