Ultrasonic Thermometer: Temperature Remote-Sensing Technique using the Ultrasonic System

C.-C. Tong, T.-C. Chang, K.-L. Wen, and W.-S. Jwo (Taiwan)


Temperature measurement, Remotesensing, Ultrasonicsystem, Timeofflight TOF, Speed of sound as a functionof temperature.


The goal of this article is to report on the design, implementation, and testing of an ultrasonic thermometer that can be used to accurately and remotely measure the surface temperature of an object. The speed of sound is proportional to air temperature and experiences a drastic change near the surface of a heat source. Accordingly, a hot surface will cause the time-of-flight (TOF) of an ultrasonic pulse to decrease as the pulse travels to the object and back to the source. The proposed system described in this article is designed to be sensitive to this change in TOF and is calibrated to relate the TOF measurement to an actual temperature reading. A 7th order polynomial is used to describe the functional relation between surface temperature and signal time-of flight. Experimental testing of this function fit results in an error of 0.85 C0 .

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