Infrared Thermometer
Introduction
How do infrared thermometers work? The most basic design consists of a lens to focus the infrared (IR) energy on to a detector, which converts the energy to an electrical signal that can be displayed in units of temperature after being compensated for ambient temperature variation. This configuration facilitates temperature measurement from a distance without contact with the object to be measured. As such, the infrared thermometer is useful for measuring temperature under circumstances where thermocouples or other probe type sensors cannot be used or do not produce accurate data for a variety of reasons. Some typical circumstances are where the object to be measured is moving; where the object is surrounded by an EM field, as in induction heating; where the object is contained in a vacuum or other controlled atmosphere; or in applications where a fast response is required.
Why should I use an infrared thermometer to measure temperature in my application? Infrared pyrometers allow users to measure temperature in applications where conventional sensors cannot be employed, specifically, in cases dealing with moving objects (i.e., rollers, moving machinery, or a conveyor belt), or where non-contact measurements are required because of contamination or hazardous reasons (such as high voltage), where distances are too great, or where the temperatures to be measured are too high for thermocouples or other contact sensors.
What is meant by Field of View, and why is it important? The field of view is the angle of vision at which the instrument operates, and is determined by the optics of the unit. To obtain an accurate temperature reading, the target being measured should completely fill the field of view of the instrument. Since the infrared device determines the average temperature of all surfaces within the field of view, if the background temperature is different from the object temperature, a measurement error can occur. OMEGA offers a unique solution to this problem. Many OMEGA infrared pyrometers feature patented laser switchable from circle to dot. In the circle mode a built-in laser sighting creates a 12-point circle which clearly indicates the target area being measured. In the dot mode a single laser dot marks the center of the measurement area.
How can I mount the infrared pyrometer? The pyrometer can be of two types, either fixed-mount or portable. Fixed mount units are generally installed in one location to continuously monitor a given process. They usually operate on line power, and are aimed at a single point. The output from this type of instrument can be a local or remote display, along with an analog output that can be used for another display or control loop. Battery powered, portable infrared ‘‘guns’’ are also available; these units have all the features of the fixed mount devices, usually without the analog output for control purposes. Generally these units are utilized in maintenance, diagnostics, quality control, and spot measurements of critical processes.
Infrared Thermometer Types