Active thermography is an attractive new technique for the nondestructive inspection of materials and structures. This technique uses a thermal perturbation to stimulate the response of the part being evaluated. Dedicated image processing is necessary to recover quantitative information about possible buried low thermal conductance defects. A technique is presented which allows recovery of the complete temporal history curve of the sample following the thermal stimulation, taking into account the typical limitations of digital systems both in terms of speed to capture images and available memory to hold them. The technique is based on the use of a logarithmic time scale to record the observational data. Such a time scale is shown to allow acquisition of infrared images over long periods of time without exceeding the computer memory capacity while retaining all the important features of the temperature history curve following the thermal perturbation necessary to detect low thermal conducting defects.
Electrical and Computer Engineering, Volumes 1 and 2 4 p (SEE N93-30215 11-31)
- Pub Date:
- Infrared Inspection;
- Nondestructive Tests;
- Image Processing;
- Infrared Imagery;
- Quality Assurance and Reliability