Non-contact infrared thermometers are widely used in medical and industrial application. In medical applications, digital thermometers have been replacing mercury stick thermometers due to more convenient measurements and also due to the hazard of mercury in legacy thermometers. The ear type thermometers, for instance, are non-contact thermometers that measure the infrared energy radiated from the ear canal. They use thermopiles and thermistors to measure the temperature. Thermopiles generate an output voltage proportional to the energy absorbed. The thermistor measures the cold-junction temperature of the thermopile. The thermopile and thermistor measurements are used to calculate the compensated temperature. This post will show you how simple it is to build a digital infrared thermometer circuit using a thermopile.
The Melexis MLX90614 is a digital non-contact thermopile for non-contact temperature measurements. Both the IR sensitive thermopile detector chip and the signal conditioning ASIC are integrated in the same TO-39 can. Integrated into the MLX90614 are a low noise amplifier, 17-bit ADC and powerful DSP unit thus achieving high accuracy and resolution of the thermometer.
All you need to do is, download the library and add it to the Arduino IDE. The library even contains a simple code to read the Thermopile and which display the result via the serial monitor.
To make it more exciting, we connected an LCD to the Arduino and displayed the results on there.