Laboratory NDT systems for Laser-excited Thermography

Laser-excited thermography is a non-contact, non-destructive testing method that is very well suited for the characterisation of weld seams, thin layers and material joints. The method is particularly used when heating must take place very precisely in time and space and without contact. The energy can be applied in pulses or periodically. Due to the Fourier analysis, the technique is very robust and also works under difficult environmental conditions. LTvis is expandable with all other Edevis excitation sources and software modules.

LTvis – made for fast inspections, for example of weld seams, coatings, etc.

  • Laser excited thermography is a non-contact testing method
  • Ideal for the characterisation of welds and for layer characterisation
  • Precise and fast flaw detection
  • Excellent for automated tests in the process cycle
Laser Thermography
Principle of Laser Thermography

Principle of Laser-excited Thermography

Laser thermography can be used both as pulse-phase thermography and as lockin thermography. The optical lockin thermography (LIT) method is based on heat flow analysis. It is often referred to as heat flow thermography.

The surface of the examined object is heated with laser light. The resulting heat flow into the material is altered by thermal obstacles such as pores, detachments or material thickness variations of the object. Heat accumulation causes “hot spots” to form on the surface, which are detected by imaging with an infrared camera. The sensitivity of the method is very high due to the use of Fourier analysis. The evaluation is not only carried out on one image, but on a whole sequence of images. From this, a phase and amplitude image is calculated by means of a Fourier transformation. In the phase image, interfering effects resulting from different emission coefficients or inhomogeneous excitation are significantly reduced. The statement about the interface state and/or the material thickness or the coating thickness is now possible.

Typical Applications of Laser-Thermography

Valve seat ring with concealed porosity. Due to the conical mirror and the colinear design, the entire inner surface can be inspected before machining.
Non-contact grinding burn detection on reference samples (before nital etching)
Characterisation of cylinder bore surfaces
Particle detection on electrodes: Coating and metal particles detectable on anode and cathode.


  • Testing of weld seams, brazed seams
  • Layer analysis (impurities, inclusions,…) 
  • Layer thickness measurements
  • Testing of bonded joints

LTvis Software

DisplayImg Software Module LTvis

The LTvis software module allows the complete control and activation of edevis lasers. Safety aspects as well as laser parameterization are controlled by the software. Both edevis lasers of type FL and NT are supported. Important parameters such as laser power, pulse length and delay or modulation frequency as well as the evaluation frequencies can be preset.

The software parameterizes the edevis laser via the serial port and controls the excitation power during the measurement via the analog interface of the Edevis Signal Generator (ESG). All parameters and result values are stored as metadata with the measurement result image files.

DisplayImg Professional »

Laser protection housing

The edevis laser safety cabin effectively protects against laser radiation and ensures safe working without further protective equipment (laser safety goggles). The built-in safety PLC and locking of the pneumatic lift doors result in the highest possible work safety.

At the same time, the integrated optical table enables professional test setups. The optionally available additional modules “X95” and “Microbench” allow an efficient setup with further optical components in the beam path.

The optionally available monitoring camera provides continuous insight into the measurement process.

Technical Data

LaserLTvis 100 NTLTvis 250 NTLTvis 50 FLLTvis 300 FL
Output power100 W250 W50 W300 W
Power supply230 V / 16 A230 V / 16 A230 V / 16 A230 V / 16 A
CoolingAir / WaterWaterAir / WaterAir/ Water
Wavelength938 nm938 nm1070 nm1070 nm
Housing19”, 4 HU19”, 3 HU19″, 3 HU19″, 4 HU

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