Thermographic lock-in excitation using phase-adaptive lasers
Thermographic lock-in excitation with phase-adaptive lasers uses modulated laser radiation to generate periodic thermal waves and precisely locate defects. Phase shifts in the detector signal enable accurate depth determination.
Physico-chemical mechanism of action
The technique uses a phase-adaptive laser that is modulated to generate periodic thermal waves. This thermal treatment changes the material's thermal conductivity and causes the material to heat and cool in different ways. Detection of these temperature changes is done by a thermal sensor that captures phase shifts in the signal.
Metallurgical relevance & risks in welding
This technique is particularly useful for precisely locating defects and cracks in complex components. It enables detailed analysis of thermal treatment and can help identify defect sources and make improvements. However, there is a risk that incorrect settings or inaccurate phase shifts can distort the detector signal, leading to misinterpretations.
Workshop practice & action instructions
To use the technique effectively, the following steps should be observed:
1. Calibrate the device: Make sure the laser and thermal sensor are properly calibrated.
2. Prepare the material: Remove all surface conditions and determine the optimal thermal treatment time.
3. Modulate the laser radiation: Use phase-adaptive modulation to generate periodic thermal waves.
4. Analyze the detector signal: Monitor the phase shifts in the detector signal and adjust the settings if necessary.
5. Interpret defects: Use the precise detection capability to locate defects and cracks.