A novel lens free high-accuracy InGaAs radiation thermometer for radiation temperatures above 300°C
- A novel high-accuracy radiation thermometer designed for laboratory applications and based on an InGaAs photon detector is presented. In contrast to other radiation thermometers, no imaging optics is used for collecting the radiation. By using a set of two equally sized optical apertures at fixed distances from the detector and a short distance of the thermometer from the radiation source, the size-of-source effect of the instrument is minimized. The radiation thermometer is designed for temperature measurements from 300°C upwards. Technical details of the radiation thermometer together with the measured reference function according to the ITS-90 up to 962°C and its temporal stability are presented. The size-of-source effect of the novel lens-free radiation thermometer is compared with the lens-based InGaAs reference radiation thermometer of the Physikalisch-Technische Bundesanstalt.