Microbolometer FPA Calibration via On-Board Coarse and External Fine Correction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current methods for calibrating microbolometer focal plane arrays (FPAs) are time-consuming and expensive due to the need for extensive data collection and processing, requiring multiple iterations of image capture, upload, calculation, and download, which can take up to ten hours for a single temperature range.
Innovation Solution
A method that utilizes an on-board processor in thermal cameras to perform coarse calibration and an external computer for fine calibration, reducing the need for time-consuming data communication by calculating and applying non-uniformity corrections locally and sending only the fine corrections for external processing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If blind non-uniformity corrections are generated using the prior art method of capture/upload/calculation/download/flash-write performed up to eighty times, then calibration precision is improved, but calibration time increases to up to ten hours
Solution Approach 1:
The patent divides the calibration process into two distinct stages: a first stage performing coarse calibration with reference and detector NUCs applied in the FPA, and a second stage performing fine calibration with external computer processing. This segmentation allows the time-consuming iterative process to be reduced while maintaining calibration precision, as the coarse calibration provides a good initial state that requires fewer refinement iterations.
Solution Approach 2:
The patent applies preliminary coarse calibration corrections (reference NUCs and detector NUCs) to the FPA before performing the fine calibration calculations on the external computer. This preliminary action establishes a baseline calibration state that significantly reduces the number of iterative refinement cycles needed, thereby reducing total calibration time while maintaining precision.
2Measurement precision
If extensive data collection and processing is performed for calibration, then calibration accuracy is improved, but productivity decreases due to the time-consuming nature of the process
Solution Approach 1:
The patent segments the data processing workload between the FPA (coarse calibration with reference and detector NUCs) and the external computer (fine calibration). This segmentation enables parallel processing capabilities and reduces the bottleneck of data communication, allowing multiple FPAs to be calibrated simultaneously or in rapid succession, thereby improving productivity while maintaining calibration accuracy.
Solution Approach 2:
The patent introduces an intermediary external computer system that performs the computationally intensive fine calibration calculations. This intermediary handles the complex data processing tasks that would otherwise bottleneck the FPA calibration process, enabling faster calibration throughput while maintaining high accuracy through sophisticated algorithms.
3Measurement precision
If multiple iterations of image capture, upload, calculation, and download are performed, then non-uniformity correction precision is improved, but device complexity increases due to the multi-step process
Solution Approach 1:
The patent segments the calibration process into distinct functional blocks: reference NUC application, detector NUC application, fine calibration calculation, and fine correction application. Each segment has a specific purpose and can be independently optimized or implemented, reducing the overall system complexity while maintaining high correction precision through focused processing at each stage.
4Loss of time
If coarse calibration with reference and detector NUCs is applied before fine calibration, then calibration time is reduced, but initial calibration precision may be insufficient
Solution Approach 1:
The patent performs preliminary coarse calibration using reference NUCs and detector NUCs to establish a baseline correction state. This preliminary action is intentionally less precise but sufficiently accurate to provide a good starting point for the subsequent fine calibration process, thereby reducing total calibration time while the final precision is achieved through the fine calibration refinement.
Solution Approach 2:
The patent uses the results from the coarse calibration as feedback for the fine calibration process. The fine calibration algorithms use the coarse calibration state as an initial condition and iteratively refine the corrections based on actual measurement data, ensuring that the final precision requirements are met while benefiting from the time savings of the preliminary coarse calibration.
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 from hours to minutes, allowing for faster and more efficient calibration of multiple thermal cameras simultaneously, eliminating the bottleneck of slow data communication and flash memory writing.
Implementation Method 1
A microbolometer is an elemental infrared detector that utilizes a material whose electrical resistance changes as a function of temperature
Implementation Method 2
the absorbed incident infrared radiation to generate a temperature change in the bolometer material
Data Source
AI summary
On-board non-uniformity correction calibration methods for a microbolometer focal plane array in a thermal camera are disclosed. The methods include performing first calculations in the processor unit of the thermal camera to generate and apply a set of coarse correction bias voltages to the detector elements. The method also includes performing calculations in the external computer based on image data collected by the thermal camera with the coarse correction bias voltages applied to the detector elements to generate a set of fine correction bias voltages. The method also includes downloading the fine correction bias voltages to the thermal camera and applying the fine correction voltages to the detector elements to establish a fine calibration of the microbolometer focal plane array.