Photothermal radiometry is a non-contact, non-destructive inspection method that is very well suited for the characterization of thin layers, hardening depths, grinding burn detection, and other challenging applications. This heat flow method is used particularly when extremely high measurement accuracy is required. The measurement using photothermics is much faster than a materialographic analysis using cuts, polishing and microscopy, and, after appropriate calibration, enables a real-time analysis of hardening depths. The process is used both in production and in research and development.
ForaTherm – no more cutting
- Allows for non-destructive characterization of surface engineered components (after calibration)
- Realtime inspection
- From random sampling to 100% inline inspection
Principle of photothermal radiometry
The photothermal method is based on periodic surface heating using laser light. The modulated heat flows from the surface into the interior of the component, whereby the heat flow is influenced by the material properties and the sample geometry. An infrared detector continuously records the radiation intensity-proportional signal from the surface, which is analyzed by a lock-in amplifier for amplitude and phase. The phase can be linked to certain material parameters such as hardness or layer thickness by means of calibration measurements. This requires both photothermal measurements and a subsequent destructive test of representative reference samples. For imaging measurements, the components must be scanned.
Typical ForaTherm applications
- Measurement of case hardening depth (chd)
- Measurement of layer thickness
- Detection of grinding burn
- Measurement of porosity in thin layers
- Detection of missing adhesion of thin layers
- Detection of covered corrosion
The software for controlling the laser and the kinematics and for data acquisition is customized.
|Bandwidth||0.01 Hz – 200 kHz|
|Power supply||230 V / 10A|
|Housing||19” / 12 RU|
|Laser protection||optional, e.g. L x W x H 1200 mm x 900 mm x 800 mm|
|Kinematics||optional, e.g. xyz linear stages and rotation stage|