Broadband multi-LED reference emitter for the high-speed calibration of non-contact temperature measuring devices

Non-contact temperature measurement using photodiode or camera-based systems is used in almost all industries to monitor, control and regulate thermal processes. The quality of the processed components and the reject rate depend largely on the reliability and accuracy of the measurement, which can only be ensured by periodic calibration. However, with today's state-of-the-art calibration furnaces, this is too time consuming and costly for some. A key advantage of an LED light source is the compact design of the fiber-optic-based measuring head for calibrating temperature measurement systems in the wavelength range of 400 to 1700nm in confined spaces. Another advantage is the very short time required to calibrate a test point, which saves more than 90% of the time and not only opens up new possibilities for optimizing quality assurance, but also improves the availability of the systems. The system enables power densities in the fiber optic based homogenized calibration head comparable to those of a calibration furnace up to 1400°C with a 1 inch opening. Individual temperatures can be set in less than a minute. The individual emitters are actively stabilized and their optical power is controlled with 0.1% stability. Using an innovative beam shaping and control concept, 40 LEDs and 4 filtered halogen radiation sources are superimposed to physically reproduce the temperature radiation of blackbody radiators or real surfaces in the wavelength range of Si or InGaAs sensors.