No-Moving-Parts Dual Spectral Imager With Blackbody Drift Correction
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Solution Overview
Problem
Infrared imaging devices with uncooled microbolometer detectors face challenges in maintaining sensitivity and reliability due to environmental temperature changes causing signal drift, especially when used for long-term monitoring without maintenance, and existing drift correction methods are inadequate for complex optics systems.
Innovation Solution
A dual-wedge-shaped component system with fixed filters and a blackbody radiation source is used to separate and filter infrared radiation into two wavelength bands, allowing for simultaneous imaging and drift correction without moving parts, maintaining high sensitivity through a low f-number optical design.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Difficulty of detecting and measuring
If spectral filtering techniques are used to detect gas clouds in infrared wavelength bands, then detection capability for hazardous gases is improved, but device cost increases due to the need for expensive infrared detectors
Solution Approach 1:
The optical system is segmented into multiple optical paths, each with dedicated spectral filters for specific wavelength bands. This allows the use of cost-effective uncooled microbolometer detectors while achieving specialized infrared detection capabilities through spatial separation of spectral filtering functions.
2Measurement precision
If a large focusing lens numerical aperture (low f-number) is designed to increase detector sensitivity, then sensitivity to radiation of interest is improved, but system complexity increases due to the need for moving components
Solution Approach 1:
The patent replaces moving optical components with fixed spectral filtering elements (prisms, beam splitters, or beam combiners) that achieve wavelength band separation without mechanical movement. This maintains the low f-number optical design for high sensitivity while eliminating the complexity and reliability issues associated with moving parts.
3Reliability
If filtering techniques without moving parts are implemented via prisms or beam splitters, then system reliability is improved, but numerical aperture decreases thereby decreasing sensitivity
Solution Approach 1:
The patent resolves the sensitivity loss by introducing a third dimension - multiple optical paths arranged spatially. Each path uses fixed filtering elements, but the overall system maintains high numerical aperture by distributing the filtering function across multiple dimensional paths rather than requiring a single complex filtering element that would block light.
4Measurement precision
If drift correction is performed using environment radiation monitoring, then measurement accuracy is improved, but device complexity increases due to additional optical components
Solution Approach 1:
The optical system is designed with multi-functionality where the same optical paths and detectors used for primary gas detection also serve to monitor environment radiation. The fixed spectral filtering elements simultaneously perform wavelength selection and provide reference signals for drift correction, eliminating the need for separate correction subsystems.
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 reliable and accurate infrared imaging with reduced maintenance needs by correcting for environmental drift, ensuring quantitative gas detection in complex environments.
Implementation Method 1
directing radiation from a field of view of the scene by the first wedge-shaped component through the image forming optical component
Implementation Method 2
directing radiation from a field of view of the scene by the first wedge-shaped component through the image forming optical component onto a first region of an uncooled detector
Implementation Method 3
filtering the directed radiation by the first wedge-shaped component to allow radiation in the first wavelength band to be imaged
Implementation Method 4
uncooled detectors, such microbolemter type arrays
Implementation Method 5
projecting radiation from a blackbody radiation source by at least one of the first or second wedge-shaped components through the image forming optical component onto the third detector region
Data Source
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Figure 3A~4
AI summary
A device images radiation from a scene. An image forming optical component forms an image of the scene on an uncooled detector having two separate regions. A first filter allows radiation in a first wavelength band to be imaged on the first detector region. A second filter allows radiation in a second wavelength band to be imaged on the second detector region, Two fixedly positioned wedge-shaped components each direct radiation from the scene through the image forming optical component onto the detector through an f-number of less than 1.5. A blackbody source positioned within, the.device reduces drift induced by -environmental, changes surrounding the devices. The blackbody source projects radiation through one of the wedge- shaped components onto a region of the detector that does not receive radiation from the scene. Pixel signals produced from the scene radiation are modified based on pixel signals produced from the blackbody.