Ratio of infrared thermometer measurement distance to measured target
The optical system of an infrared thermometer collects energy from a circular measuring spot and focuses it on a detector, with optical resolution 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 spot. The latest improvement in infrared optics is the addition of a near-focus feature, which provides measurements on small target areas and also protects against background temperatures.
Infrared thermometers receive invisible infrared energy emitted by a wide range of objects themselves. Infrared radiation is part of the electromagnetic spectrum, which includes radio waves, microwaves, visible light, UV, R-rays and X-rays. Infrared is located between visible light and radio waves, infrared wavelengths are often expressed in microns, the wavelength range of 0.7 microns - 1000 microns, in fact, 0.7 microns - 14 microns band used for infrared thermometer.
Infrared thermometers are lightweight, small, easy to use, and can reliably measure hot, dangerous, or hard-to-reach objects without contaminating or damaging the object being measured.
Infrared thermometers can be divided into monochromatic pyrometers and two-colour pyrometers (radiation colorimetric pyrometers) according to the principle. For single-colour pyrometers, the area of the target to be measured should fill the field of view of the pyrometer when conducting temperature measurement. It is recommended that the target size exceeds 50% of the field of view size. If the target size is smaller than the field of view, the background radiant energy will enter the pyrometer's visual acoustic signature and interfere with the temperature reading, resulting in an error. Conversely, if the target is larger than the pyrometer's field of view, the pyrometer will not be affected by the background outside the measurement area. In the case of a colorimetric pyrometer, the temperature is determined by the ratio of the radiant energy in two separate wavelength bands. Therefore, when the measured target is small and does not fill the field of view, the presence of smoke, dust, obstruction on the measurement path, attenuation of the radiant energy, are not significant impact on the measurement results. For small and in motion or vibration of the target, the colourimetric thermometer is * the best choice. This is due to the small diameter and flexibility of the light, which allows the transmission of optical radiation energy over curved, blocked and folded channels.
