Infrared Camera Timing Correction for Pulsed Thermography
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Solution Overview
Problem
Infrared camera measurement systems used in thermography face significant timing errors in active thermography due to the non-coincidence of the heating pulse and integration period with the frame sync signal, leading to inaccuracies in temperature measurements, especially in early post-flash frames.
Innovation Solution
The system measures the on-set and duration of the flash pulse by detecting disturbances in pixel values during the frame read-out, allowing for precise timing adjustments to correct temperature measurement equations and prevent saturation by offsetting the flash pulse from the integration period.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the integration time is assumed to coincide with the frame sync signal onset, then the measurement system is simple to operate, but significant timing errors occur in early post-flash frames
Solution Approach 1:
The system performs preliminary measurement of the actual integration time offset relative to the frame sync signal before conducting thermographic measurements. This preliminary characterization of the timing relationship allows subsequent measurements to use corrected time values, eliminating the need for operators to manually adjust timing parameters while maintaining high measurement accuracy.
2Reliability
If the flash pulse coincides with the integration period, then the temperature measurement is maximized, but pixel saturation occurs in early frames
Solution Approach 1:
The system dynamically adjusts the assumed integration time for each frame based on the measured actual integration time offset. By using frame-specific timing corrections rather than a fixed assumption, the system maintains accurate temperature measurements without causing pixel saturation, as each frame is processed with its correct timing parameters.
3Productivity
If the integration time precedes the frame sync signal, then the camera can operate in integrate while read mode, but the measurement time differs significantly from the apparent time
Solution Approach 1:
The system implements feedback by measuring the actual integration time offset and using this information to correct temperature measurement equations. The measured offset value feeds into the data processing algorithm, which automatically adjusts the time parameters for each frame, ensuring accurate measurements while maintaining the efficient integrate while read mode operation.
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 method provides accurate temperature measurements by correcting timing errors and preventing saturation, enhancing the reliability of thermographic data analysis and reducing errors in non-destructive testing applications.
Implementation Method 1
An infrared (IR) camera is typically used for thermography to measure the infrared radiation emitted from a sample as it returns toward a steady state temperature
Implementation Method 2
Pulsed thermography is widely used in the nondestructive evaluation of component parts used in aerospace and the power generation industry
Data Source
AI summary
A method for measuring the timing of a flash event including capturing a first image prior to the commencement of a flash event. Capturing a second image during the occurrence of the flash event, and comparing the second image to the first image to determine a time related characteristic of the flash event.