As a pyrometric optical temperature measurement method, thermography has a lot of special features that distinguishes it from conventional technical temperature measurement with contacting sensors: contactless, nonreactive thermographic temperature measurement can be conducted from a distance with very short response times. It can be used on moving measurement objects and can be used on live sources and encapsulated measurement objects behind protective windows. Lenses with different fields of view can be used to adapt to the geometry of the measurement object and the measurement points. This allows this temperature measurement method to be used for microscopic small details in the micrometer range as well as for objects that may be kilometres away.
In principle, thermographic cameras can measure object temperatures in a range from far below room temperature up to more than 3,000 °C with absolute accuracies in the percentage range. However, real measurement objects and measurement environments usually require a high degree of expertise and experience in design, setup and, if necessary, error compensation of thermographic measurement arrangements.
The visualization of images, also known as thermograms recorded by thermographic cameras, can be performed in different ways. Best known are gray value or so-called false colour representations, in which each temperature value is assigned a gray level or a certain colour. Therefore, the user can get a very clear overview of the temperature distribution on the measurement object and immediately detect anomalies such as hotspots and discontinuities, which can indicate hidden faults for example. Another important feature is the ability of thermographic cameras to depict rapid changes in temperature or temperature distributions: Thermographic sequences, which can be captured in full frame mode at frame rates of up to several hundred hertz and in subwindow modes up to several kilohertz, allow temporal resolutions down to the submillisecond range. This ability ensures the user to record temporal profiles of thermal processes in detail for a better understanding, and if necessary to optimise them.
A special field, the so-called active thermography is utilising these capabilities to make hidden defects in specimens like cracks, blowholes and delamination visible by the help of mainly artificial temperature changes in a non-destructive way.
Due to their modern variable interfaces, our thermographic cameras can be used easily for process optimisation and quality assurance in almost all fields of industrial metrology and image processing. Based on thermal images and sequences it becomes obvious if the manufacturing process is running within defined parameters or deviations will occur. As a result, product quality increases while costs decrease.