laser thermometer on desk

Infrared Thermometer Gun - All You Need to Know

Infrared Thermometer 

What are they?

Infrared thermometers or temperature guns takes the temperature of the object your gun is pointed at. They are often referred to as non-contact as you do not need to physically touch the object you are measuring. This is extremely useful for measuring the heat off dangerously hot objects like industry ovens or to check faulty electrical circuits. The use for them is wide and varied, from your common kitchen tool to industry heavy duties ones. 

How do they work?

The infrared thermometer works by sending out a red light (light) to the object that needs to be measured, which will then be reflected back and converted into electrical signals. The electrical signal is proportional to the infrared energy emitted which is also proportional to its temperature. To prevent interference from external factors that may alter the readings, a special plastic window is made to only allow certain frequencies through.

Are they accurate?

Whilst thermometers can vary in their accuracy they are still within around ±1% or ± 1℃. There are other factors which may affect the readings;

  • The user's body temperature
  • The reflectivity of the measured object
  • Dirt on the lens of the gun
  • Steam or dust between the object and gun
  • Distance and size of the object being measured
  • The gun's temperature difference to the environment

Minimizing the factors of dirt, steam, and difference in temperature from the environment to the gun and the human body temperature can easily be managed with care and preparation. Allow for up to 20 minutes for the gun to go to the new environment's temperature (for example if you stepped indoors to a cool place from a hot outdoors). Wearing gloves can also reduce the user's body temperature. 

Reflectivity and Emissivity

Different materials will reflect light and heat differently, for example, shiny metal and glossy paint will have a high reflection compared to wood. The first and easy way to counter this is to use a nonreflective tape to wrap around or on the object, you want to measure if this is not possible or the object is too hot then choose a thermometer gun with Emissivity setting. 

Emissivity is the measure of how much heat an object emits. This is measured from a range of 0 does not really emit heat (non-emissive) to 1 which emits a lot of heat (emissive). A good rule of thumb to find the emissivity of an object is to look at its color. The darker it is the greater the emissivity.

Distance and Size

There is a common misconception that the laser point is exactly where the laser gun measures. This is only used as a guide to point the gun, as the range in where the gun takes the measurement is larger than the dot the further away you are from the object. 

Most thermometers have a distance to spot ratio of 12:1 which translate to about 2.5 cm at 30 cm or about an inch to 12 inches. Be extra considerate when taking the temperature of a small area at a greater distance as you may end up covering areas beyond the intended target.

Where to purchase a non-contact Thermometer Measuring Laser gun

The Perfect Prime TM series non-contact thermometer guns have the emissivity setting as well as distance to spot ratio feature, enabling users to have the greatest accuracy when measuring temperatures at a distance. 


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