Infrared Camera Calibration Using Integration Time Variation
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Solution Overview
Problem
Infrared cameras require lengthy calibration processes due to differences in photodetector responsivity, especially for MCT detectors, which necessitate frequent recalibration and involve the use of precise blackbody thermoelectric coolers, increasing setup time and costs.
Innovation Solution
A non-uniformity correction calibration method that calculates correction coefficients based on changes in integration time rather than temperature, allowing for calibration at a constant temperature and reducing the need for thermoelectric coolers, thereby simplifying the calibration process and reducing time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional NUC calibration based on temperature adjustment is used, then correction coefficients can be obtained, but calibration time becomes excessively long and complex cooling equipment is required
Solution Approach 1:
The patent changes the calibration parameter from temperature to integration time. Instead of varying the blackbody temperature to obtain correction coefficients, the method varies the integration time while maintaining a constant temperature reference. This parameter substitution eliminates the need for temperature cycling and complex cooling equipment, dramatically reducing calibration time while still providing accurate correction coefficients for different integration time conditions
Solution Approach 2:
The patent extracts the temperature control requirement from the calibration process. By separating the temperature stabilization function (maintaining constant reference temperature) from the calibration variable (integration time), the method eliminates the need for dynamic temperature adjustment and complex thermoelectric cooler systems, keeping only the essential constant temperature reference
2Measurement precision
If precise blackbody thermoelectric coolers are used for calibration, then accurate temperature control is achieved, but system complexity and costs increase
Solution Approach 1:
The patent removes the thermoelectric cooler and temperature cycling mechanism from the calibration system. By extracting the temperature control function and replacing it with a simple constant temperature reference, the method eliminates complex cooling equipment while maintaining sufficient temperature stability for accurate calibration
Solution Approach 2:
The patent replaces expensive, complex thermoelectric cooler systems with a simple, low-cost constant temperature reference source. This substitution uses inexpensive equipment that maintains temperature sufficiently for calibration purposes without requiring the sophisticated temperature control mechanisms of conventional systems
3Reliability
If conventional calibration with temperature cycling is used, then comprehensive correction is achieved, but setup time and operational delays increase
Solution Approach 1:
The patent changes the independent variable in the calibration process from temperature to integration time. This allows calibration to be performed rapidly by adjusting electronic integration time parameters rather than physically cycling temperatures, enabling the camera to become operational much faster while still achieving reliable correction across different operating conditions
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 significantly reduces calibration time and costs while maintaining camera reliability, particularly for MCT detectors, by using a constant temperature reference and eliminating the need for complex thermoelectric cooler systems.
Implementation Method 1
an array of photodetectors which collects the incident radiation
Implementation Method 2
a constant temperature reference value... by means of a blackbody
Data Source
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AI summary
A method and a system for calibrating an infrared camera (100) is disclosed. The method comprises the steps of setting an integration time value for an array of photodetectors (104) of the infrared camera (100) and acquiring a calibration scene having a homogeneous temperature; applying a plurality of variations on the integration time value and reading out corresponding thermal responses for the array of photodetectors (104); averaging the plurality of thermal responses of the array of photodetectors (104) for each variation applied to the integration time value and calculating a plurality of coefficients of correction for the array of photodetectors (104). Advantageously, according to the present disclosure, calibration time in factory or start-up time for those IR cameras that uses MCT detectors can be reduced. In turn, less complexity for the test equipment is required.