FPA Gain Normalization and Non-Uniformity Correction
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Solution Overview
Problem
Focal plane arrays (FPAs) face challenges in producing accurate image data due to varying temperature, which causes non-constant system gain and pixel-to-pixel variations, despite conventional methods like thermoelectric cooling, as these methods require maintaining a constant temperature for calibration, limiting their effectiveness.
Innovation Solution
A method that normalizes FPA system gain and corrects pixel non-uniformity by determining the FPA temperature, calculating system gain and non-uniformity correction maps using empirically derived coefficients, and applying these corrections to produce temperature-independent and temperature-dependent image data without temperature control, using a module connected to the FPA and ROIC.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If thermoelectric cooling is used to control FPA temperature, then system gain stability is improved, but device complexity and power consumption increase
Solution Approach 1:
The patent replaces the mechanical/thermal system (thermoelectric cooling) with an electronic computation system. Temperature-dependent gain variations are corrected by measuring FPA temperature and applying computational correction factors to the image data, eliminating the need for physical temperature control hardware while achieving the same stability goal
Solution Approach 2:
The patent changes the approach from controlling the physical parameter (temperature) to controlling the data parameter (gain correction). By measuring temperature and applying corresponding gain corrections to the image data, the system achieves gain stability without maintaining constant physical temperature
2Measurement precision
If thermoelectric cooling is used to maintain constant FPA temperature, then image accuracy is improved, but power consumption increases
Solution Approach 1:
The patent substitutes active thermal management (power-consuming thermoelectric cooling) with passive temperature measurement and computational correction. The FPA operates without active cooling, and temperature-dependent variations are corrected through electronic processing of the captured data
Solution Approach 2:
The system uses the FPA's own temperature measurements to self-correct its output. By measuring its operating temperature and applying pre-determined correction factors, the system compensates for its own temperature-dependent variations without external intervention or additional power-consuming components
3Measurement precision
If correction maps are created at specific temperatures, then pixel non-uniformity correction is improved, but adaptability to temperature changes deteriorates
Solution Approach 1:
The patent transitions from static correction maps (fixed at specific temperatures) to dynamic correction. The system measures the current FPA temperature and selects or calculates the appropriate correction factors in real-time, enabling continuous adaptation to temperature changes while maintaining correction accuracy
Solution Approach 2:
The patent performs preliminary characterization of pixel non-uniformity at multiple temperatures during manufacturing or calibration. These pre-determined correction factors are stored and later applied based on measured operating temperature, combining advance preparation with real-time adaptability
Data Source
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AI summary
A method (200) of normalizing FPA system gain and correcting pixel non-uniformity for varying temperature includes determining an FPA temperature (202), calculating an FPA system gain as a function of the FPA temperature (204), and applying the FPA system gain at the FPA temperature to condition output of the FPA to produce temperature independent image data. The method also includes calculating a non-uniformity correction map on a pixel by pixel basis for the FPA (210), wherein non-uniformity correction for each pixel is a function of the FPA temperature, and applying the non-uniformity correction map to the imaging data from the FPA (212) to produce temperature dependent non-uniformity corrected image data. An imaging system (100) includes a focal plane array (FPA) (102), a temperature sensor (106) operatively connected to measure temperature of the FPA, and a module (112) configured for system gain correction and non-uniformity correction as described above.