The ratio of the measuring distance of the thermometer to the measured target
The optical system of the infrared thermometer collects energy from a circular measuring spot and focuses it on the detector. The optical resolution is defined as the ratio (D:S) of the distance from the infrared thermometer to the object to the measured spot size. The larger the ratio, the better the resolution of the infrared thermometer and the smaller the measured spot size. Laser aiming, only to aid in aiming at the measuring point. A recent improvement in infrared optics is the addition of a near-focus feature, which provides measurements on small target areas and is immune to background temperature effects.
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, R-rays, and X-rays. Infrared is between visible light and radio waves. Infrared wavelengths are commonly expressed in microns, and the wavelength range is 0.7 microns to 1000 microns. In fact, the 0.7 microns to 14 microns band is used for infrared thermometers.
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 single-color thermometers and two-color thermometers (radiation colorimetric thermometers) according to the principle. For a monochromatic thermometer, when measuring temperature, the area of the target to be measured should fill the field of view of the thermometer. It is recommended that the measured target size 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 and acoustic symbols of the thermometer and interfere with the temperature measurement readings, causing errors. Conversely, if the target is larger than the pyrometer's field of view, the pyrometer will not be affected by background outside the measurement area. For colorimetric thermometers, the temperature is determined by the ratio of radiant energy in two independent wavelength bands. Therefore, when the target to be measured is small, does not fill the field of view, and there are smoke, dust, and obstructions on the measurement path, which attenuate the radiation energy, it will not have a significant impact on the measurement results. For small and moving or vibrating targets, the colorimetric thermometer is the best choice. This is due to the small diameter of the light rays and their flexibility to transport light radiant energy over curved, blocked and folded channels.
