Switchable Liquid Crystal Optical Filter for Dual-Spectral Imaging
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Solution Overview
Problem
Existing camera systems face challenges in acquiring high-resolution images of both visible and infrared light using the same sensor array, as current solutions like non-converged sensors result in decreased resolution and signal-to-noise ratio due to partial utilization of the sensor area.
Innovation Solution
An electronically switchable optical filter using liquid crystals that can be configured to block or transmit specific spectral light sub-bands, including visible and infrared, regardless of polarization, allowing the entire sensor array to be utilized for infrared imaging while rejecting interfering visible wavelengths.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If non-converged sensors are used to acquire both visible and infrared images, then the camera can capture multiple spectral bands, but the resolution and signal-to-noise ratio decrease due to partial utilization of the sensor area
Solution Approach 1:
The patent employs a dynamically switchable optical filter that can transition between different spectral transmission states. The filter is controlled by a controller that switches it to a first state for infrared imaging and a second state for visible imaging, allowing the same sensor array to be fully utilized for each spectral band at different times, thereby maintaining high resolution and signal-to-noise ratio while achieving multi-spectral capture capability
Solution Approach 2:
The patent implements time-sequential acquisition where the optical filter is switched between states to discard unwanted spectral bands during specific acquisition periods. The controller switches the filter to block visible light during infrared acquisition and block infrared light during visible acquisition, ensuring the entire sensor array is dedicated to one spectral band at a time, thus recovering full sensor utilization for each imaging mode
2Measurement precision
If the entire sensor array is used for infrared imaging, then the signal-to-noise ratio improves, but visible light interference must be blocked
Solution Approach 1:
The patent introduces an optical filter as an intermediary component between the scene and the sensor array. This filter selectively transmits infrared wavelengths while blocking visible wavelengths during infrared imaging mode, allowing the entire sensor array to be utilized for infrared detection without contamination from visible light interference. The filter is switched out of the optical path during visible imaging mode to allow full visible spectrum transmission
Solution Approach 2:
The optical filter exhibits wavelength-selective transmission properties, with different transmission characteristics for different spectral bands. During infrared imaging, the filter has high transmission for infrared wavelengths and high blocking for visible wavelengths, optimizing the signal-to-noise ratio for infrared detection while eliminating visible light interference
3Measurement precision
If a switchable optical filter is added to enable spectral selection, then image quality in specific bands improves, but the device complexity increases
Solution Approach 1:
The patent employs a single optical filter component that performs multiple functions: it acts as an infrared pass filter during infrared imaging, as a visible pass filter during visible imaging, and can be positioned in or out of the optical path as needed. This multi-functional filter, combined with a control system, replaces what would otherwise require separate sensor arrays or multiple specialized filters, thereby managing device complexity while achieving high spectral selectivity and image quality
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 image acquisition in both visible and infrared spectral bands, with the optical filter switching between reflection and transmission states to optimize sensor array usage, thereby improving image quality and efficiency.
Implementation Method 1
a first plurality of liquid crystals configured to dynamically form cholesteric phase structures in a reflection state that block right-handed circularly polarized light in a spectral light sub-band and transmit light outside of the spectral light sub-band
Implementation Method 2
block right-handed circularly polarized light in a spectral light sub-band and transmit light outside of the spectral light sub-band
Implementation Method 3
dynamically form a nematic phase arrangement in a transmission state that transmits light in the spectral light sub-band
Data Source
AI summary
An optical filter for a camera is switchable between a reflection state and a transmission state. The optical filter includes a first plurality of liquid crystals configured to dynamically form cholesteric phase structures in the reflection state that block right-handed circularly polarized light in a spectral light sub-band and transmit light outside of the spectral light sub-band. The first plurality of liquid crystals dynamically forms a nematic phase arrangement in the transmission state that transmits light in the spectral light sub-band. The optical filter further includes a second plurality of liquid crystals configured to dynamically form cholesteric phase structures in the reflection state that block left-handed circularly polarized light in the spectral light sub-band and transmit light outside of the spectral light sub-band. The second plurality of liquid crystals dynamically form a nematic phase arrangement in the transmission state that transmits light in the spectral light sub-band.