How to Determine the Size of the Target Using an Infrared Thermometer
Infrared thermometers can be divided into single-color thermometers and two-color thermometers (radiation colorimetric thermometers) based on their principles. For a monochromatic thermometer, when measuring temperature, the measured target area should fill the field of view of the thermometer. 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 signals of the thermometer and interfere with the temperature measurement reading, causing errors. In contrast, if the target is larger than the thermometer's field of view, the thermometer will not be affected by the background outside the measurement area. For colorimetric thermometers, the temperature is determined by the ratio of radiated energy in two independent wavelength bands. Therefore, when the measured target 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 targets that are in motion or vibrating, colorimetric thermometers are the best choice. This is due to the small diameter and flexibility of light, which can transmit optical radiation energy in curved, blocked and folded channels.
For two-color thermometers in the infrared era, the temperature is determined by the ratio of radiated energy in two independent wavelength bands. Therefore, when the measured target is small, does not fill the site, and there is smoke, dust, or obstruction on the measurement path that attenuates 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 in motion or vibrating; targets that sometimes move within the field of view or may partially move out of the field of view, under these conditions, using a two-color thermometer is the best choice. If it is impossible to aim directly between the thermometer and the target, or the measurement channel is curved, narrow, or blocked, a two-color fiber optic thermometer is the best choice. This is due to its small diameter and flexibility, which can transmit optical radiation energy on curved, blocked and folded channels, so it can measure targets that are difficult to access, have harsh conditions or are close to electromagnetic fields.
