Final answer:
An infrared thermometer or pyrometer is used for measuring temperature by holding it close to an object without contact. It reads infrared radiation emitted by the object. This type of thermometer is advantageous for temperature measurement in cases where traditional contact thermometers are not suitable.
Step-by-step explanation:
The type of thermometer that is read by holding it as close as possible to the product without actually touching it is an infrared thermometer or pyrometer. Such thermometers measure the infrared radiation which varies with temperature. They are used in various applications where contact with the object is not possible or advisable, such as checking the temperature of an aircraft carrier's ventilation system, or for measuring body temperature more accurately than traditional alcohol thermometers by placing them gently in the ear canal.
The phenomenon of the alcohol column going down in an alcohol thermometer before going up when placed in a hot liquid is due to the initial contraction of the alcohol due to its contact with the cooler surface of the thermometer's bulb before it starts to absorb heat and expand.