To measure a surface temperature, the user aims the TIF7620 IR Thermometer at the target, presses a button, and reads the temperature display. The device has an optical lens that collects the radiated infrared energy from the object and focuses it on the detector. The detector converts the energy into an electrical signal that's amplified and displayed as a temperature reading. An infrared thermometer measures temperature by sensing the magnitude of radiated energy at infrared frequencies. Using this data and the actual temperature of the detector, the thermometer calculates the temperature of the surface that emitted the energy.