An infrared (IR) thermometer is a sensor measuring the temperature of an object without coming into contact with it. Using infrared technology, noncontact IR thermometers quickly and conveniently measure surface temperature, providing fast temperature readings of hot, dangerous or hard-to-reach surfaces without object contact or contamination. This method provides several readings per second, whereas contact methods can take minutes with each measurement.

The ability to measure surface temperature without breaching the target's exterior is crucial in demanding manufacturing environments. Noncontact thermometers are especially useful in process heating applications, which can involve extreme operating conditions.

When searching for the correct noncontact IR temperature measurement instrument, a number of factors should be considered. In addition to your budget parameters and manufacturer/product reliability, the type of measurement application and instrument accuracy are important.

Application Considerations

Physical factors to consider when choosing an IR thermometer include temperature range, material, interfering gases and ambient temperature. Also keep in mind:

    The target must be optically (infrared-optically) visible to the thermometer.

  • The optics of the sensor must be protected from environmental conditions.

  • Only surface temperatures can be measured, with the emissivity of different material surfaces taken into account.

Also, will the instrument be part of an integrated process control solution or used for occasional measurements obtained as reference data?

Accuracy Requirements

Users should examine the thermometer's performance and consider the degree of accuracy required by the application. Be sure to check the manufacturer's accuracy definition for inclusion of emissivity values -- the amount of readable energy released by the object.

Environmental conditions, such as steam, dust or smoke, could prevent accurate measurement by obstructing the unit's optic. Noise, electromagnetic fields or vibrations are other conditions that should also be considered.

The temperature surrounding the target, known as ambient temperature, could affect the accuracy of any measurement. Some IR thermometers respond better than others to environments with high ambient operating temperatures.

New Sensor Technology

Recent innovations in IR technology have resulted in sensors that are small enough to be installed just about anywhere, yet perform as well as much larger systems. The new sensors reduce costs, increase reliability and provide smaller units of measurement.

IR devices offering a combination of user-selectable and scalable analog signal outputs can enable seamless integration into existing control equipment or OEM systems. RS-232 communications eases sensor configuration, and is valuable for troubleshooting in hard-to-reach locations. Optional RS-485 communications allows multiple sensors to be networked on two wires, which can reduce installation cost and facilitate custom equipment design.

In addition, the higher ambient operating temperature range of today's advanced IR sensors enables installation in locations where air-cooling is either not practical or affordable. This feature is particularly beneficial for builders or users of ovens and dryers.

For more information

Contact Raytek. Call (800) 227-8074 or visit