How an Infrared Thermometer Works


There are several different ways to measure the temperature of an object; the old way was to insert a thermometer into an object and gauge the reaction of the mercury inside the thermometer. Modern thermometers, even analogue ones, no longer use mercury. They use a safer liquid that is coloured so as to be easily visible. Furthermore, you don’t need to insert a thermometer anymore. If you work in the restaurant industry, you can check the temperature of food by simply shining an infrared thermometer on it. The infrared thermometer gauges the temperature of an object without ever actually touching it; this is great for food service in which it is unhealthy and unsanitary for the waitstaff to touch other people’s food. The thermometer only measures the surface temperature; if you are trying to gauge how well something has been cooked, you need to use an internal thermometer. An infrared device is sufficient for surface evaluations, though. Here’s how they work.

Black Body Radiation

By its technical definition, black body radiation is the radiation that is emitted from a non-reflective and solid surface. In this case, it would be the food or the plate. Black body radiation is a very narrow spectrum of radiation that depends completely on the temperature of an object. So, as the temperature of an object changes, so does the amount of black body radiation. If you can measure the amount of radiation, you can accurately measure the temperature of the object. This is how an infrared thermometer works. You shine the measuring tools at an object and the lens in the object measures the amount of radiation. It then converts that into a number which is the temperature.

The Uses

Restaurants use infrared thermometers frequently to check if food is at the right temperature. It only measure the surface, though; so you should not trust it to keep you safe from foodborne illness. You need an internal thermometer for that. Infrared thermometers are not only useful in a restaurant though.

Many different industries use infrared thermometers for various reasons. In mechanical and industrial capacities, the infrared thermometer can be used to make sure that a material is safe to touch or move. Also, you can gauge if a machine is running too hot. For example, the friction that comes from a machine not being properly aligned or properly oiled will create heat. That heat can be a sign that something has gone wrong with your machine; however, if it’s normally too hot to touch, it can be difficult to gauge the amount of a temperature increase. Therefore, the only way to accurately assess this is with a hands-free measuring device. Infrared thermometers can also be used in a medical setting.

The temperature of someone’s forehead is an admittedly imprecise way to determine if someone has a fever. Nonetheless, taking multiple readings can give you an indication if the temperature is in fact trending upwards.

Infrared thermometers are used in many different settings. They are used by restaurant and medical professionals, as well as private individuals in different applications.