Infrared Thermometer

An infrared thermometer is a thermometer which infers temperature
from a portion of the thermal radiation sometimes called black-body radiation emitted by the object being measured.

Infrared thermometers have good accuracy when measuring most objects, but shiny, reflective surfaces can be a challenge.

The reason for this is that not all materials emit the same amount of infrared energy when they are at the same temperature.
Infrared (IR) thermometers are not harmful. 
IR thermometers do no emit radiation, only measuring it like a digital camera.