Tunable Optical Filter for Multi-Spectral Thermal Imaging
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Solution Overview
Problem
Current radiometrically calibrated imaging systems face challenges with emissivity variations and limited dynamic range due to fixed aperture optics and reliance on emissivity estimations, which affect accuracy and functionality, especially in complex scenes with non-uniform temperature profiles.
Innovation Solution
A multi-spectral imaging system utilizing a tunable optical filter coupled with a broadband imaging system, allowing discrete infrared wavelengths to be selected and processed for emissivity-independent thermal imaging, and dynamically adjusting the quality factor to control radiation and prevent pixel saturation/underfilling, thereby expanding the temperature range and accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If fixed aperture optics are used in radiometric infrared imaging systems, then the system structure is simple, but the dynamic range of temperature data is limited
Solution Approach 1:
The patent applies dynamics by replacing fixed aperture optics with a variable aperture optical system that can dynamically adjust its opening size. This allows the system to adapt to different temperature ranges and radiance levels, enabling both low and high temperature measurements within the same imaging system without requiring multiple fixed systems.
2Measurement precision
If multiple fixed optical filters are used for multi-wavelength measurements, then discrete wavelength sampling is achieved, but the system becomes bulky and slow with high power requirements
Solution Approach 1:
The patent applies universality by using a single tunable optical filter that can select multiple discrete wavelengths sequentially, replacing the need for multiple fixed filters. This single component performs the function of multiple filters, reducing system complexity, size, and power requirements while maintaining the capability for multi-wavelength measurements.
Solution Approach 2:
The patent replaces mechanical filter wheel systems with an electronically controlled tunable optical filter. This substitution eliminates bulky mechanical components, reduces power consumption, and enables faster wavelength switching without the complexity of electromechanical devices.
3Adaptability or versatility
If detector pixel integration time is varied to expand temperature range, then temperature dynamic range increases, but measurement time and system complexity increase
Solution Approach 1:
The patent applies dynamics by implementing variable aperture optics that can quickly adjust the amount of radiated energy reaching the detector. This dynamic control allows the system to handle both low and high temperature measurements within a single integration time period, eliminating the need for multiple integration time measurements and reducing total measurement time.
4Ease of operation
If emissivity estimation is used in radiometric systems, then temperature measurement is possible, but accuracy is reduced due to emissivity variations
Solution Approach 1:
The patent applies parameter changes by measuring radiated energy at multiple discrete wavelengths and using ratio techniques to calculate temperature. This method changes the measurement approach from relying on single-wavelength emissivity estimates to using multi-wavelength ratios that cancel out emissivity effects, thereby improving temperature accuracy without sacrificing ease of operation.
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 system achieves accurate emissivity-corrected temperature data and extended dynamic range, enabling true imaging capabilities and improved performance in complex scenes by generating monochromatic images at various wavelengths and adjusting radiation levels, surpassing limitations of conventional systems.
Implementation Method 1
A multi-spectral imaging system utilizing a tunable optical filter coupled with a broadband imaging system, allowing discrete infrared wavelengths to be selected and processed
Implementation Method 2
measures the radiated energy of a scene at selected discrete wavelengths in the 2 μm-10 μm range using a focal plane array-based imaging camera
Implementation Method 3
An image processing system may process selected monochromatic infrared images by using a ratio technique to generate an emissivity-independent thermal image of the scene
Implementation Method 4
The tunable optical filter may also be used to adjust a quality factor and control an amount of radiated energy that is passed to an image sensor of the broadband imaging system thereby acting as an aperture
Data Source
AI summary
A multi-spectral imaging system utilizing tunable optics is disclosed. Various disclosed systems include a tunable optical filter coupled to a broadband imaging system. The tunable optical filter allows discrete infrared wavelengths to pass to the broadband imaging system so that monochromatic infrared images of a scene may be captured. An image processing system may process selected monochromatic infrared images by using a ratio technique to generate an emissivity-independent thermal image of the scene. The tunable optical filter may also be used to adjust a quality factor and control an amount of radiated energy that is passed to an image sensor of the broadband imaging system thereby acting as an aperture to account for both low and high radiance portions of the scene.