Principle and application of infrared thermometer

1. Why use a non-contact infrared thermometer?

Non-contact infrared thermometers use infrared technology to quickly and easily measure the surface temperature of an object. No mechanical contact with the object is required to quickly measure the temperature reading. Just aim, press the trigger, and read the temperature data on the LCD display. Infrared thermometers are light, small, easy to use, and can reliably measure hot, dangerous or hard-to-reach objects without contaminating or damaging the object. Infrared thermometers can measure several readings per second, while contact thermometers take several minutes to measure per second.

2. How does an infrared thermometer work?

Infrared thermometers receive invisible infrared energy emitted by various objects themselves. Infrared radiation is part of the electromagnetic spectrum, which includes radio waves, microwaves, visible light, ultraviolet rays, R rays and X rays. Infrared is located between visible light and radio waves. Infrared wavelengths are often expressed in microns, with a wavelength range of 0.7 microns to 1000 microns. In fact, the 0.7 micron to 14 micron band is used for infrared thermometers.

3. How to ensure the temperature measurement accuracy of infrared thermometers?

The undisputed understanding of infrared technology and its principles is its accurate temperature measurement. When the temperature is measured by an infrared thermometer, the infrared energy emitted by the object being measured is converted into an electrical signal on the detector through the optical system of the infrared thermometer, and the temperature reading of the signal is displayed. There are several important factors that determine the accurate temperature measurement. The most important factors are emissivity, field of view, distance to the light spot and the position of the light spot. Emissivity, all objects reflect, transmit and emit energy, and only the emitted energy can indicate the temperature of the object. When the infrared thermometer measures the surface temperature, the instrument can receive all three types of energy. Therefore, all infrared thermometers must be adjusted to read only the emitted energy. Measurement errors are usually caused by infrared energy reflected from other light sources. Some infrared thermometers can change the emissivity, and the emissivity values ​​of various materials can be found in published emissivity tables. Other instruments are fixed and preset to an emissivity of 0.95. This emissivity value is for the surface temperature of most organic materials, paints or oxidized surfaces, and it is necessary to apply a tape or flat black paint to the measured surface to compensate. When the tape or paint reaches the same temperature as the base material, the temperature of the tape or paint surface is measured, which is its true temperature. Distance to spot ratio, the optical system of the infrared thermometer collects energy from the circular measurement spot and focuses it on the detector. The optical resolution is defined as the ratio of the distance from the infrared thermometer to the object to the size of the measured spot (D:S). The larger the ratio, the better the resolution of the infrared thermometer and the smaller the measured spot size. Laser aiming, only used to help aim at the measurement point. The latest improvement in infrared optics is the addition of a close focus feature, which can provide accurate measurement of small target areas and prevent the influence of background temperature. Field of view, make sure the target is larger than the spot size when the infrared thermometer is measuring. The smaller the target, the closer it should be. When accuracy is particularly important, make sure the target is at least twice the spot size.

4. How to measure temperature with an infrared thermometer?

To measure temperature with an infrared thermometer, aim the infrared thermometer at the object to be measured, press the trigger to read the temperature data on the LCD of the instrument, and make sure to arrange the distance to spot size ratio and field of view. There are several important things to remember when using an infrared thermometer:

1. Only surface temperatures are measured. Infrared thermometers cannot measure internal temperatures.
2. Temperature cannot be measured through glass. Glass has very specific reflection and transmission characteristics that do not allow accurate infrared temperature readings. However, temperature can be measured through the infrared window. Infrared thermometers are best not used to measure the temperature of shiny or polished metal surfaces (stainless steel, aluminum, etc.).
3. Locate hot spots. To find hot spots, aim the instrument at the target and then make an up and down scanning motion on the target until the hot spot is located.
4. Pay attention to environmental conditions: steam, dust, smoke, etc. It blocks the instrument's optical system and affects accurate temperature measurement.
5. Ambient temperature. If the infrared thermometer is suddenly exposed to an ambient temperature difference of 20 degrees or more, allow the instrument to adjust to the new ambient temperature within 20 minutes.

5. What are the most common infrared thermometer applications?

Non-contact infrared thermometers have many applications. The most common ones are:

1. Automotive industry: Diagnosing cylinders and heating/cooling systems.
2. HVAC: Monitoring air stratification, supply/return records, furnace performance.
3. Electrical: Check for faulty transformers, electrical panels and connectors.
4. Food: Scan management, service and storage temperatures.
5. Others: Many engineering, base and renovation applications. (end)