Infrared Portable Thermometers Infrared Thermometer measure the surface temperature of an object. It's optics sense emitted, reflacted and transmitted energy, which is collected & focused on a detector. It's electronics translate information into a temperature reading which is displayed on the unit. We offer RAYTEK.usa, OPTEX & GRILLO.japan, make portable handheld type, mounting type & specialised sensors for online temperature measurement. IR Thermometers are used to measure temperature from -30ºC to 3000ºC.