Tunable Liquid Crystal Optical Filter for Spectral Imaging
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing camera systems face challenges in acquiring images in different spectral light sub-bands with high signal-to-noise ratio, as specialized filter arrays often result in reduced resolution and signal-to-noise ratio due to partial sensor array usage.
Innovation Solution
A tunable optical filter with switchable liquid crystal layers that can block or transmit specific spectral light sub-bands, allowing the same sensor array to capture images across a broad spectrum, including ultraviolet, visible, NIR, and IR light, using differential sensors and active or passive illumination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If specialized filter arrays are used to acquire images in different spectral light sub-bands, then spectral imaging capability is improved, but resolution and signal-to-noise ratio are reduced due to partial sensor array usage
Solution Approach 1:
The patent applies dynamics by replacing static specialized filter arrays with a dynamic tunable optical filter system. The optical filter can be electrically tuned to different spectral sub-bands using liquid crystal layers, allowing the same sensor array to be fully utilized for each spectral band. This dynamic adjustment enables high-resolution spectral imaging without the resolution loss inherent in fixed filter arrays that only use portions of the sensor array.
Solution Approach 2:
The patent implements universality by creating a single optical filter system that can perform multiple spectral imaging functions. The tunable optical filter serves as a universal component that can be adjusted to capture images across various spectral light sub-bands (visible, NIR, SWIR, etc.), replacing the need for multiple specialized filter arrays. This allows the complete sensor array to be used for each spectral band, maintaining high resolution and signal-to-noise ratio while achieving broad spectral coverage.
2Device complexity
If the same sensor array is used for multiple imaging types, then device complexity is reduced, but spectral selectivity and image quality deteriorate without specialized filters
Solution Approach 1:
The patent uses dynamics to enable a single sensor array to reliably capture images across multiple spectral bands. The electrically tunable optical filter dynamically adjusts its spectral transmission characteristics based on the desired imaging band, ensuring high spectral selectivity and image quality for each band. This eliminates the need for multiple specialized sensor arrays while maintaining reliable spectral imaging performance.
Solution Approach 2:
The patent applies parameter changes by modifying the optical filter's spectral transmission parameters through electrical control. The liquid crystal layers in the optical filter can be tuned to change their optical properties, allowing the filter to selectively transmit or block specific spectral bands. This parameter adjustment mechanism enables the same sensor array to achieve reliable spectral selectivity and image quality across different imaging types without requiring physical changes to the sensor array itself.
3Adaptability or versatility
If optical filter blocks spectral light in reflection state, then spectral selectivity is improved, but light transmission and signal intensity are reduced
Solution Approach 1:
The patent utilizes phase transitions of liquid crystal materials to achieve spectral selectivity without significant light loss. The liquid crystal layers can switch between different phases (transmissive and reflective states) based on applied voltage, enabling precise spectral filtering. When in transmissive mode, the filter allows maximum light transmission to the sensor array, maintaining high signal intensity. When spectral selectivity is needed, the filter transitions to reflective mode for specific bands while maintaining overall system efficiency through active illumination.
Solution Approach 2:
The patent introduces active illumination as an intermediary to compensate for any light transmission losses. The illumination source provides controlled spectral light that ensures sufficient signal intensity reaches the sensor array after passing through the tunable optical filter. This intermediary illumination system works in conjunction with the optical filter to maintain both spectral selectivity and adequate signal intensity, allowing the filter to operate in reflection state for selectivity while the illumination compensates for transmission reduction.
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
Enables high signal-to-noise ratio imaging in various spectral light sub-bands by selectively tuning the optical filter to block or transmit specific spectral ranges, allowing the same sensor array to be used for multiple imaging types without reducing resolution or increasing noise.
Implementation Method 1
The optical filter includes a plurality of liquid crystal layers switchable between a reflection state and a transmission state. Each liquid crystal layer is configured to block spectral light in a different spectral light sub-band and transmit spectral light outside of the spectral light sub-band in the reflection state.
Implementation Method 2
Each liquid crystal layer is configured to block spectral light in a different spectral light sub-band and transmit spectral light outside of the spectral light sub-band in the reflection state.
Data Source
AI summary
A camera includes an optical filter for a sensor array of the camera. The optical filter includes a plurality of liquid crystal layers switchable between a reflection state and a transmission state. Each liquid crystal layer is configured to block spectral light in a different spectral light sub-band and transmit spectral light outside of the spectral light sub-band in the reflection state, and to transmit spectral light in the spectral light sub-band in the transmission state. An active illuminator of the camera is configured to emit active light in a selected spectral light sub-band. One or more of the plurality of liquid crystal layers is switched from the transmission state to the reflection state to tune the optical filter to block spectral light in all but the selected spectral light sub-band. The sensors of the sensor array are addressed to measure spectral light in the selected spectral light sub-band.