Optimal control of laser applications

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Quantum Design, the UK distributor of the InfraTec Image IR Series of thermography cameras, explains how the technology can be used for the optimal control of a series of laser applications.

Laser applications are of vital importance in today’s industry, science and medicine, because the properties of laser radiation result in numerous different applications. Among numerous industrial lasers, there are those that involve the application of thermal energy for material processing. This is where permanent monitoring and control of the heat development play an important role in order to process materials in accordance with their properties and comply with quality and safety standards.

Laser applications that use ther­mo­graphy successfully include laser sintering, laser cutting, laser welding and laser soldering.

Thermography enables the non-contact visualisation and analysis of the heat flow in the respective measurement and test objects or components. The temperature measurement on their surface allows the energy input of the laser to be controlled and ensures that the object to be processed is heated optimally.

The advantages of process control with thermography include non-contact and non-reactive temperature measurement, and the mapping of heat flows in components to gain a complete understanding of the process. Thanks to high measurement accuracy, the control of precisely adjusted energy input and a reduction of thermal load is possible with the exact calculation of the final energy input by laser into the component due to complete geometrical and temporal recording of temperature distributions in highly dynamic processes. The optimum positioning of non-visible lasers (UV laser, IR laser) is also possible, as is the reliable monitoring of the heating and cooling processes of materials.

The overarching benefits of using thermography include the possibility for the early detection of errors in production, active avoidance of rejects and minimisation of returns, plus the optimisation of process and cycle times as well as pre- and post-processing. The non-destructive testing of laser welded joints is also possible, as is direct laser control based on the observed object temperature in real-time. While the derivation of correlations between process parameters and (melting) temperatures also offers advantages.

Infrared cameras for the investigation of laser applications have to meet very specific requirements. This applies, for example, with regard to the temporal resolution: it is characteristic for working with a laser to have short laser action times, where heat input takes place within fractions of a second. This requires measurements with high image frequencies in full and partial images. Especially in micro-material processing with pulsed laser light, the demands on thermography systems – such as the ImageIR 8300 hs – are very high because the processes run at high speeds.

The thermal and geometric resolution of infrared cameras is equally important. Depending on the process and material, lasers can be used to generate very large and small temperature differences, which must be monitored precisely and continuously. Here, InfraTec offers different functions of the cameras, such as HighSense-mode, HDR function, binning mode and geometric resolutions in the HD range.

Often, it is necessary to monitor very precisely – even on fine structures or locally – which input of thermal energy is induced and what the processing temperatures of all materials involved in the process are. Consequently, the combination of geometric and thermal resolution of the camera determines the success of the respective application.

Infrared cameras for laser materials processing include the new InfraTec ImageIR 6300 Z – a small, lightweight, compact system for universal use in thermographic temperature measurements in a wide range of applications. Its excellent price-performance ratio and user-friendliness result from the systematic use of the latest technologies in optics, detector and electronics.

qd-uki.co.uk

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