The temperature of a distant object can also be determined by analysis of the infrared radiation from the object. Radiometers operating in the infrared range serve as the basis for many instruments, including heat-seeking devices in missiles and devices for spotting and photographing persons and objects in the dark or in fog. Medical uses of infrared radiation range from the simple heat lamp to the technique of thermal imaging, or thermography . A thermograph of a person can show areas of the body where the temperature is much higher or lower than normal, thus indicating some medical problem. Thermography has also been used in industry and other applications.
Some lasers produce infrared radiation.