Thermographic Lock-In Excitation
Thermographic lock-in excitation is an active thermography technique with modulated thermal excitation for precise detection of small material defects. It minimizes variations in surface emissivity through phase-shifted evaluation.
Physico-chemical mechanism of action
Thermographic lock-in excitation uses modulated thermal excitation to detect material defects. The excitation is generated in a known frequency band and the material's response to this excitation is measured. Phase-shifted evaluation minimizes the influence of surface emissivity variations, enabling more precise detection.
Metallurgical relevance & risks in welding
This technique is particularly useful for detecting small material defects and deformations in weld areas. Incorrect excitation parameters or inaccurate evaluation can lead to missed or false results, which can compromise quality assurance.
Workshop practice & action instructions
To successfully use thermographic lock-in excitation, the following steps must be observed:
1. Excitation settings: The excitation frequency and amplitude must be set precisely to achieve the desired material behavior.
2. Evaluation: The phase-shifted evaluation must be carried out correctly to compensate for surface emissivity variations.
3. Calibration: Regular calibration of the measuring equipment is necessary to ensure the accuracy of the results.