The ratio of distance measured by an infrared thermometer to the measured target
The optical system of an infrared thermometer collects energy from a circular measuring 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 and the size of the measured spot (D: S). The larger the ratio, the better the resolution of the infrared thermometer, and the smaller the size of the measured spot. Laser aiming is only used to assist in aiming at the measurement point. The new improvement in infrared optics is the addition of near focus characteristics, which can provide measurement for small target areas and prevent the influence of background temperature.
Infrared thermometers receive invisible infrared energy emitted by various objects themselves. Infrared radiation is a part of the electromagnetic spectrum, including radio waves, microwaves, visible light, ultraviolet, R-rays, and X-rays. Infrared is located between visible light and radio waves, and its wavelength is often expressed in micrometers, ranging from 0.7 micrometers to 1000 micrometers. In fact, the 0.7 micrometer to 14 micrometer band is used for infrared thermometers.
The infrared thermometer is lightweight, small in size, easy to use, and can reliably measure hot, dangerous, or difficult to reach objects without polluting or damaging the measured object.
Infrared thermometers can be divided into monochromatic thermometers and bichromatic thermometers (radiation colorimetric thermometers) based on their principles. For a monochromatic thermometer, when measuring temperature, the area of the measured target should fill the field of view of the thermometer. It is recommended that the size of the tested object exceed 50% of the field of view. If the target size is smaller than the field of view, the background radiation energy will enter the visual sound symbol of the thermometer to interfere with the temperature measurement reading, causing errors. On the contrary, if the target is larger than the field of view of the thermometer, the thermometer will not be affected by the background outside the measurement area. For colorimetric thermometers, the temperature is determined by the ratio of radiation energy within two independent wavelength bands. Therefore, when the measured target is very small, does not fill the field of view, there is smoke, dust, obstruction on the measurement path, and there is attenuation of radiation energy, it does not have a significant impact on the measurement results. For small targets that are in motion or vibration, a colorimetric thermometer is the best choice. This is due to the small diameter and flexibility of the light, which can transmit radiation energy through curved, obstructed, and folded channels.
