Etude et Réalisation d’un Thermomètre sans Contact

Abstract

Temperature measurement plays a central role in many fields, including medicine, industry, the food sector and home automation. Contact-based measurement methods, although well established, show limitations when the target is inaccessible, fragile, moving, or when a risk of contamination must be avoided. This dissertation addresses the study and realization of a non-contact thermometer based on the detection of the infrared radiation emitted by any body whose temperature is above absolute zero. The first chapter reviews the physical fundamentals of thermal radiation (Planck's, StefanBoltzmann's and Wien's laws), the notion of emissivity, and the main types of infrared sensors used in non-contact thermometry. The second chapter details the electronic design of the realized system, built around an MLX90614 infrared thermopile sensor, an Arduino microcontroller in charge of acquisition and processing, and an LCD display combined with an audible and visual alarm triggered when a temperature threshold is exceeded. The third chapter presents the practical realization of the prototype, the experimental protocol that was set up, and the results obtained, compared with those of a reference contact thermometer. The results show that the realized prototype allows fast, non-contact temperature measurement, with a limited average deviation from the reference measurement, while highlighting the influence of emissivity, distance and environment on measurement accuracy.