Pixel Non-Uniformity Correction Using Temperature-Dependent Maps
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Solution Overview
Problem
Focal plane arrays (FPAs) in imaging systems face significant pixel non-uniformity issues due to manufacturing variance and temperature changes, which are typically addressed through calibration maps and thermoelectric cooling, but these methods are not effective at low light levels and require constant temperature maintenance.
Innovation Solution
A method to calculate and apply a non-uniformity correction map on a pixel-by-pixel basis using empirically derived coefficients and FPA temperature, allowing for temperature-dependent correction of imaging data without the need for temperature control devices like thermoelectric cooling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If thermoelectric cooling is used to control FPA temperature, then temperature stability is improved, but device complexity and power consumption increase
Solution Approach 1:
The patent replaces the mechanical/physical thermoelectric cooling system with an electronic/software-based correction approach. Instead of physically controlling temperature, the system uses temperature sensors to monitor FPA temperature and applies computational correction maps to compensate for thermal effects, thereby eliminating complex temperature control hardware while maintaining imaging accuracy across varying temperatures
Solution Approach 2:
The patent changes the approach from controlling the physical temperature parameter to correcting the signal parameters based on temperature measurements. By using temperature-dependent correction maps that adjust pixel responses based on measured temperature, the system compensates for thermal effects without attempting to physically maintain constant temperature, thus reducing device complexity
2Stability of the object's composition
If thermoelectric cooling is used to control FPA temperature, then temperature stability is improved, but power consumption increases
Solution Approach 1:
The patent replaces the energy-intensive thermoelectric cooling system with a low-power electronic correction approach. Instead of continuously powering cooling devices to maintain temperature, the system uses minimal power for temperature sensing and computational correction, dramatically reducing overall power consumption while maintaining accurate imaging across temperature variations
Solution Approach 2:
The system uses the FPA's own temperature sensor to monitor its thermal state and self-corrects for temperature effects using stored correction maps. This self-service approach eliminates the need for external active cooling systems, allowing the FPA to compensate for its own thermal variations without consuming additional power for temperature control hardware
3Manufacturing precision
If calibration maps are used to correct pixel non-uniformity, then manufacturing variance is addressed, but temperature changes reduce correction effectiveness
Solution Approach 1:
The patent transitions from static calibration maps to dynamic, temperature-dependent correction maps. Instead of using a single fixed correction map, the system generates or selects correction maps based on measured temperature, allowing the correction parameters to adapt dynamically to changing thermal conditions. This enables the system to maintain pixel uniformity across a range of temperatures rather than being optimized for a single calibration temperature
Solution Approach 2:
The patent makes the correction parameters temperature-dependent by using measured temperature values to determine which correction map to apply. This parameter change approach allows the correction system to adapt to different operating temperatures, maintaining manufacturing precision while gaining temperature adaptability through the use of temperature-sensitive correction parameters
4Measurement precision
If correction maps are applied at a specific temperature, then accurate image data is produced at that temperature, but accuracy decreases at different temperatures
Solution Approach 1:
The patent implements dynamic adaptation by selecting or generating correction maps based on real-time temperature measurements. Instead of being fixed for a single temperature, the correction system dynamically adjusts to match the current operating temperature, ensuring accurate image data across the full temperature range rather than only at the calibration temperature
Solution Approach 2:
The system uses temperature sensors to continuously monitor FPA temperature and feeds this information back to the correction system. This feedback loop allows the correction maps to be selected or adjusted based on actual temperature conditions, maintaining measurement precision across varying temperatures through continuous temperature-aware correction
Data Source
Figure 1
AI summary
A method of correcting pixel non-uniformity for varying temperature includes determining an FPA temperature and calculating a non-uniformity correction map on a pixel by pixel basis for the FPA (102), wherein the non-uniformity correction for each pixel is a function of the FPA temperature and empirically derived coefficients. The method also includes applying the non-uniformity correction map at the FPA temperature to condition output of the FPA to produce temperature dependent non-uniformity corrected image data. An imaging system includes a focal plane array (FPA). A temperature sensor (106) is operatively connected to measure FPA temperature. A module (112) is operatively connected to the FPA and temperature sensor to calculate and apply a non-uniformity correction map as described above. There need be no temperature control device for the FPA. The FPA can include a buffered current mirror pixel architecture, and can include an InGaAs material for infrared imaging.