Infrared Imaging Drift Correction via Wedge Optics and Blind Pixels
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Solution Overview
Problem
Infrared imaging devices with uncooled microbolometer detectors face inaccuracies due to signal drift caused by environmental temperature changes, particularly in complex optics systems, which limits their use in unattended monitoring over extended periods without frequent maintenance, as existing correction methods like Non-Uniformity Correction (NUC) and blind pixel methods are inadequate for large or complex optics setups.
Innovation Solution
A method and device using stationary wedge-shaped optical components to focus radiation onto separate detector regions, with a blackbody radiation source projected onto a third detector region to continuously correct for environmental temperature changes, allowing for drift correction without moving parts, ensuring accurate gas distribution measurement in the long wave infrared region.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If Non-Uniformity Correction (NUC) with frequent shutter operations is used to correct signal drift, then measurement precision is improved, but device complexity and maintenance requirements increase
Solution Approach 1:
The patent extracts the drift correction function from the mechanical shutter system by implementing separate blind pixel regions that continuously monitor environmental radiation. This allows drift correction without requiring the complex moving shutter mechanism, thereby maintaining measurement precision while reducing device complexity
Solution Approach 2:
The patent introduces blind pixel regions as intermediary elements that indirectly measure environmental radiation changes. These blind pixels serve as mediators between the environment and the main detector array, providing drift correction data without requiring direct mechanical intervention through shutters
2Device complexity
If blind pixel methods are used to reduce shutter operations, then device complexity is reduced, but measurement precision deteriorates due to inability to account for temperature gradients in complex optics
Solution Approach 1:
The patent segments the detector array into functional regions: scene-viewing pixels and blind pixels. The blind pixels are further segmented into multiple regions positioned at different locations within the optics enclosure, allowing each segment to monitor specific environmental radiation sources and temperature gradients, thereby improving drift correction accuracy without requiring shutters
Solution Approach 2:
The blind pixel regions serve multiple functions: they monitor environmental radiation, track temperature gradients across the optics enclosure, and provide continuous drift correction data. This multi-functionality allows the system to maintain high measurement precision without the mechanical complexity of shutters
3Productivity
If unattended monitoring over extended periods is implemented, then productivity is improved, but reliability deteriorates due to signal drift from environmental temperature changes
Solution Approach 1:
The patent implements continuous drift correction by maintaining blind pixel regions that constantly monitor environmental radiation throughout the unattended monitoring period. This continuous action ensures that signal drift is continuously compensated, maintaining measurement reliability over extended periods without requiring periodic maintenance or recalibration
Solution Approach 2:
The blind pixel regions provide continuous feedback on environmental radiation changes and temperature gradients. This feedback is used to dynamically adjust and correct the signals from the main detector array, ensuring measurement reliability is maintained throughout extended unattended 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
This approach effectively reduces signal drift, enabling accurate and continuous monitoring of gas distributions without the need for frequent shutter operations, thereby reducing maintenance costs and ensuring reliable operation for extended periods.
Implementation Method 1
focusing radiation from the scene by a first and second substantially wedge-shaped component through an image forming optical component onto a detector
Implementation Method 2
projecting radiation from a 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
Implementation Method 3
a detector sensitive to radiation in the first and second wavelength bands, the detector being uncooled and including a separate first, second, and third detector region
Data Source
AI summary
A method reduces drift induced by environment changes when imaging radiation from a scene in two wavelength bands. Scene radiation is focused by two wedge-shaped components through a lens onto a detector that includes three separate regions. The wedge-shaped components are positioned at a fixed distance from the lens. The radiation from the scene is imaged separately onto two of the detector regions through an f-number of less than approximately 1.5 to produce a first pixel signal. Imaged radiation on each of the two regions includes radiation in one respective wavelength band. Radiation from a radiation source is projected by at least one of the wedge-shaped components through the lens onto a third detector region to produce a second pixel signal. The first pixel signal is modified based on a predetermined function that defines a relationship between second pixel signal changes and first pixel signal changes induced by environment changes.