Electromagnetic Radiation Sensor Calibration Using Band-Pass Filter
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Solution Overview
Problem
Current electromagnetic radiation detection systems face challenges with gain instabilities in FPA matrices, leading to incorrect corrections and the presence of atypical pixels, which are difficult to identify and calibrate, especially due to the need for costly and complex calibration methods that require frequent factory visits and the use of Peltier modules, causing electrical consumption and congestion issues.
Innovation Solution
An electromagnetic radiation detection system that performs two-point calibration without a Peltier module, using a band-pass filter with a predefined transmission coefficient that can move between positions to filter or not filter radiation, allowing for the evaluation of gain and offset values for each detector, enabling on-board calibration without over-declaring valid pixels and avoiding the need for hardened calibration methods.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If hardened calibration methods are used to identify atypical pixels, then pixel reliability is improved, but device complexity and cost increase due to frequent factory visits and multiple successive calibrations
Solution Approach 1:
The system performs self-calibration using an integrated black body that generates reference radiation signals within the detection system itself. This eliminates the need for external calibration equipment and frequent factory visits, allowing the system to calibrate its own detectors autonomously while maintaining pixel reliability
Solution Approach 2:
The black body serves multiple functions: it provides reference radiation for gain calibration, establishes offset values, and enables periodic recalibration throughout the system's lifetime. This multi-functional component replaces multiple separate calibration procedures and equipment
2Measurement precision
If Peltier modules are used for cooling, then detector sensitivity is improved, but electrical consumption and system congestion increase
Solution Approach 1:
The system replaces active Peltier cooling modules with passive radiative cooling through specially designed optical surfaces and enclosures. The cold finger structure with high-emissivity surfaces radiates heat to the environment, eliminating the need for electrical cooling power while maintaining detector temperatures for sensitive measurements
3Ease of manufacture
If gain calibration is performed once in factory, then manufacturing simplicity is maintained, but measurement precision deteriorates due to gain instabilities and aging over the system's 15-20 year lifetime
Solution Approach 1:
The system performs preliminary gain calibration using the integrated black body at the time of manufacture, establishing baseline gain values. The black body then enables periodic recalibration throughout the system's operational life to compensate for gain drift and aging effects, maintaining measurement precision without complex procedures
4Adaptability or versatility
If offset values are calculated in product, then adaptability to field conditions is improved, but time consumption increases due to the need for multiple acquisition sequences
Solution Approach 1:
The system combines gain calibration and offset determination into a single acquisition sequence using the black body. By presenting known reference radiation levels from the black body, the system simultaneously determines both gain and offset parameters in one operation, eliminating the need for separate calibration sequences and reducing time consumption
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 solution simplifies the calibration process, reduces electrical consumption, and allows for accurate gain and offset corrections, effectively identifying and correcting atypical pixels without the need for Peltier modules, enhancing the reliability and efficiency of electromagnetic radiation detection systems.
Implementation Method 1
at least one band-pass electromagnetic radiation filter having a predefined transmission coefficient
Implementation Method 2
a cold finger having a side wall closed at one end by an end wall... a sensor... cooled by the cold finger
Implementation Method 3
Each photodetector transforms, for example, the photons resulting from electromagnetic radiation into electron-hole pairs by the photoelectric effect
Implementation Method 4
each filter has in section in any secant plane containing the optical axis a concave shape facing the sensor having a conical-based profile and/or aspherical and reflects the focal plane inside the housing
Data Source
Figure 1A~1C
Figure 2
Figure 3
AI summary
A system (3) for detecting electromagnetic radiation is equipped with an electromagnetic radiation sensor. The sensor consists of a plurality of detectors sensitive to electromagnetic radiation and obtains images composed of pixels, each pixel being represented by at least one value from at least one detector of the sensor. The sensors must generally be cooled. Due to an effect of dispersion of individual responses from each detector of a sensor, it is essential to calibrate each detector of said sensor in gain and in offset value. A calibration of a detector requires at least two values from the detector to be acquired in order to estimate a gain and an offset value to apply to the values from said detector. The invention consists of inserting a band-pass electromagnetic radiation filter (402) with a predefined transmission coefficient into the system in order to vary the electromagnetic radiation reaching said sensor and thus to obtain, for each detector, the two values necessary for implementing the calibration.