Bolometer Array Non-Uniformity Correction Without Mechanical Shutters
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Solution Overview
Problem
Existing infrared detectors with bolometers suffer from non-uniformity and columnar appearance in images due to dispersion of electrical resistances, which current methods fail to adequately correct without increasing costs or complexity.
Innovation Solution
A method involving a detector with first and second bolometers, where the first bolometers are permanently masked and used for reference measurements, and the second bolometers are used for scene imaging, with a calculator processing these measurements to correct for non-uniformity through correlation and subtraction, eliminating the need for mechanical shutters and complex algorithms.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a mechanical shutter is implemented to collect reference images, then reference measurements can be obtained for correction, but cost and device complexity increase due to motorization requirements
Solution Approach 1:
The patent extracts the reference measurement function from a mechanical shutter system and assigns it to dedicated reference bolometers that are permanently masked. This eliminates the need for moving mechanical parts while maintaining the ability to obtain reference images for correction.
Solution Approach 2:
The patent replaces the mechanical shutter system with a static bolometer array configuration where reference bolometers are permanently masked. This substitution eliminates motorization and mechanical complexity while achieving the same reference measurement function through electrical/readout means only.
2Measurement precision
If calibration tables are stored in memory space, then correction accuracy improves, but manufacturing cost increases due to additional memory components
Solution Approach 1:
The patent merges the reference measurement function with the existing bolometer array structure. Reference bolometers are integrated into the same detector chip and readout circuitry as imaging bolometers, eliminating the need for separate memory storage components and reducing manufacturing costs.
Solution Approach 2:
The bolometer array serves dual functions: imaging bolometers capture scene information while reference bolometers (permanently masked) provide reference measurements. This multi-functionality eliminates the need for separate calibration memory components.
3Measurement precision
If complex correction algorithms are implemented, then image non-uniformity correction improves, but computational cost and processing time increase
Solution Approach 1:
The patent performs reference measurements continuously in the background using permanently masked reference bolometers. This preliminary and ongoing action provides up-to-date reference data without requiring complex post-processing algorithms, enabling real-time correction with minimal computational overhead.
Solution Approach 2:
The detector system performs self-calibration by continuously comparing imaging bolometer signals with reference bolometer signals. This self-service mechanism maintains image uniformity automatically without requiring external complex correction algorithms or significant processing time.
4Reliability
If reference measurements are taken at different temperatures, then temperature compensation improves, but measurement time and productivity decrease
Solution Approach 1:
The patent implements continuous reference measurements using permanently masked reference bolometers that operate simultaneously with imaging bolometers. This continuous action provides ongoing temperature compensation without interrupting or slowing down the imaging process, maintaining both reliability and productivity.
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 method effectively corrects pixelation and columnar effects in images while reducing computational and manufacturing costs, maintaining robustness and efficiency without additional mechanical parts.
Implementation Method 1
An infrared detector (or imager) known from the state of the art generally comprises bolometers organized in a matrix manner... these bolometers, sensitive to the temperature of the scene, see their electrical resistance vary
Implementation Method 2
a differential measurement of the currents passing through a blind bolometer and a bolometer of the bolometer matrix makes it possible to deduce the variation in electrical resistivity of the latter
Data Source
Figure 1~2
Figure 3~4a
Figure 4b
AI summary
The invention relates to a method for processing a raw image characterized by the first Pixi(i,j) and the second Pix2(i,j) raw measurements collected by first Bol1(i,j) and second Bol2(i,j) bolometers of a set of Bol(i,j) bolometers of a detector, the first Bol1(i,j) bolometers being closed, the method being executed by a computer on the basis of reference measurements PixREF(i,j) which include first Pix1REF(i,j) and second Pix2REF(i,j) reference measurements associated with the first Bol1(i,j) and second Bol2(i,j) bolometers, the method comprising: a) a correlation step between the first raw measurements Pix1(i,j) and the first reference measurements Pix1REF(i,j); b) a raw image correction step which includes the calculation of corrected measurements PixCor(i,j) of a corrected image for each bolometer Bol(i,j) based on the reference measurements PixREF(i,j) and the result of step a).