Analytische Chemie
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- Contactless temperature measurement (2) (entfernen)
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The contactless measurement of temperatures with pyrometers is state of the art and a number of different commercial devices are available. Alternatively, these temperature measurements can be performed by means of infrared cameras. In light of permanently falling costs, the application of IR cameras simply as contactless thermometers appears to be an alternative to the use of pyrometers. For a current study, the surface temperature development of a sample has to be measured and recorded with at least 20 Hz sampling rate in a temperature range between 0°C and 70°C and with a temperature resolution of 0.1 K. The absolute value of the temperature is not as important as relative changes. Due to disturbing irradiation in the SWIR and MWIR regions, the sensor should work in the LWIR. We compared two pyrometers and a low-cost infrared camera with regard to the requirements defined above. In this paper we describe the setup, the results and the data evaluation. Both, raw data and post processed data, were considered. Surprisingly, the infrared camera had by far the best performance of the considered devices. Particularly, due to the large number of pixel (160 x 120), the S/N could be reduced considerably compared to the pyrometers. We also studied the stability of the frame rate and the related time steps of the IR camera. Although the frame rate is unstable (running under Windows operating system), the output data for the time steps were found to be correct and the required time resolution was achieved.
The application of IR cameras simply as contactless thermometers appears to be an alternative to the use of pyrometers. For a current study, the surface temperature development of a sample has to be measured and recorded with at least 20 Hz sampling rate in a temperature range between 0°C and 70°C and with a temperature resolution of 0.1 K. We compared two pyrometers and a low-cost infrared camera both sensitive in the LWIR only. Surprisingly, the infrared camera had by far the best performance of the considered devices.
Contactless temperature sensing is state of the art and essential part of countless applications in the field of process control and automation. This contribution presents the case of a nondestructive thickness measurement method for polymeric coatings on concrete ground. Two pyrometers and a low-cost infrared camera were taken into account. The particular measurement results were compared with those of a more sophisticated infrared camera. It was found that the low-cost infrared camera has a lower noise level than the pyrometers, even for a single pixel. The opportunity to average over a large number of pixels and to establish a bias correction enables a further noise reduction by almost factor of 10.
Furthermore, the temporal resolution of the infrared camera was investigated by means of a well-defined thermal oscillation. It could be demonstrated that the averaged time stamps are correct and the requirement of a Minimum framerate of 50 Hz is met. Finally, the temperature transient on a polymer coated concrete block during and after a 10 s heating period was recorded with a pyrometer and the infrared camera. This experiment confirmed the suitability of the camera for the intended measurement method.