Infrared Detection Device Using Liquid Crystal Spectral Filtering
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Solution Overview
Problem
Current spectral imaging technologies for hazardous gas detection and imaging are costly and require moving parts, making them unsuitable for practical civilian and industrial applications, especially since many hazardous gases are transparent in the visible range and require infrared detection.
Innovation Solution
A low-cost device using a bistatic electronically controlled notch absorber with liquid crystal molecules that alternately images a field of view through notch and out-of-notch wavelength ranges, eliminating the need for moving parts by electronically switching between absorption and transmission states, allowing for the calculation of gas path concentration using two-wavelength passive infrared radiometry.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If spectral scanning methods with moving optical components are used, then spectral imaging capability is achieved, but device complexity and cost increase due to moving parts
Solution Approach 1:
The patent replaces mechanical scanning systems (moving mirrors, rotating filter wheels, interferometer components) with a fixed optical system that uses electronic control of liquid crystal variable filters to achieve spectral imaging. This substitution eliminates moving parts while maintaining the capability to capture spectral information across multiple wavelengths.
Solution Approach 2:
The patent uses liquid crystal variable filters that can dynamically change their spectral transmission characteristics through electrical control. This allows the system to electronically switch between different wavelength bands without mechanical movement, achieving spectral scanning functionality through dynamic material properties rather than mechanical motion.
2Measurement precision
If infrared detectors are used for hazardous gas detection, then detection sensitivity is improved, but device cost increases
Solution Approach 1:
The patent employs a single detector array that operates across a broad spectral range, allowing it to detect multiple different hazardous gases simultaneously. By using a fixed optical system with electronically controllable spectral filtering, the same detector can be used for various gas detection applications without requiring specialized detectors for each gas type, thereby reducing overall system cost while maintaining high detection sensitivity.
3Productivity
If snapshot spectral imaging methods are used, then productivity is improved, but manufacturing precision requirements increase due to exotic optical components
Solution Approach 1:
The patent uses commercially available liquid crystal variable filters and standard optical components rather than expensive, custom-fabricated exotic optical elements. The liquid crystal filters are mass-produced consumer electronics components that can be precisely controlled electronically, eliminating the need for complex precision optical fabrication while achieving snapshot spectral imaging capability.
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 device provides reliable and cost-effective detection and imaging of airborne gases by minimizing the use of moving parts and maintaining high sensitivity, enabling the quantification of gas concentration and cloud size with improved spatial and spectral resolution.
Implementation Method 1
a filtering arrangement including first and second independently controllable pluralities of radiation absorbing molecules in the second wavelength band
Implementation Method 2
A low-cost device using a bistatic electronically controlled notch absorber with liquid crystal molecules
Implementation Method 3
a detector of the radiation from the scene sensitive to radiation in the first wavelength band
Implementation Method 4
allowing for the calculation of gas path concentration using two-wavelength passive infrared radiometry
Data Source
AI summary
A device images radiation from a scene. A detector is sensitive to the radiation in a first wavelength band. A lens forms an image of the scene on the detector. A filtering arrangement includes two sets of radiation absorbing molecules. A control unit switches the filtering arrangement between two states. In the first state, all of the radiation in the first wavelength band is transmitted to the detector. In the second state, the radiation in a second wavelength band within the first wavelength band is absorbed by the radiation absorbing molecules. The control unit synchronizes the switching of the filtering arrangement with the detector. Each pixel of the image formed on the detector includes two signals. The first signal includes information from the scene radiation in the first wavelength band. The second signal excludes information from the scene radiation absorbed by the filtering arrangement in the second wavelength band.