Raytek Digital Infrared Thermometer MI3 - Digital Infrared Thermometer The Raytek MI3 digital infrared thermometer represents a new generation of performance and innovation in continuous noncontact temperature monitoring for a broad range of OEM applications and manufacturing processes. Each MI3 infrared temperature thermometer is a two piece system with a miniature sensing head and separate communications electronics. The miniature sensing head can be installed in any system and outperforms much larger sensors, making the Raytek MI3 the best valued IR temperature sensor in its class. Raytek Digital Infrared Thermometer is available through HeatSource.