Target Size Of Infrared Thermometer

Infrared thermometers can be divided into monochromatic thermometers and two-color thermometers (radiometric colorimetric thermometers) according to their principles. For the monochromatic thermometer, when measuring the temperature, the measured target area should be full of the thermometer's field of view. It is recommended that the size of the measured target exceeds 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 to interfere with the temperature 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 a two-color thermometer, the temperature is determined by the ratio of the radiant energy in two independent wavelength bands. Therefore, when the measured target is small, does not fill the site, smoke, dust, and barriers on the measurement path attenuate the radiation energy, it will not affect the measurement results. Even when the energy is attenuated by 95%, the required temperature measurement accuracy can still be guaranteed. For targets that are small and are in motion or vibration; sometimes they move in the field of view, or may partially move out of the field of view. Under this condition, using a two-color thermometer is the best choice. If it is impossible to aim directly between the thermometer and the target, and the measurement channel is bent, narrow, or obstructed, the dual-color fiber optic thermometer is the best choice. This is due to its small diameter and flexibility, which can transmit light radiation energy on curved, blocked and folded channels, so it can measure targets that are difficult to access, under harsh conditions, or close to electromagnetic fields.