Emissivity, all objects reflect, transmit and emit energy, only the emitted energy can indicate the temperature of the object. When an infrared thermometer measures surface temperature, the instrument receives all three of these energies. Therefore, all infrared thermometers must be adjusted to read only the energy emitted. Measurement errors are usually caused by infrared energy reflected from other light sources.

The ratio of distance to spot, the optical system of the infrared thermometer collects energy from the circular measuring spot and focuses it on the detector, and the optical resolution is defined as the ratio of the distance from the infrared thermometer to the object to the size of the spot to be measured (D :S). The larger the ratio, the better the resolution of the infrared thermometer, and the smaller the spot size to be measured.
Laser aiming to help aim at the measurement point. The latest improvement in infrared optics is the addition of a near-focus feature that provides accurate measurement of small target areas and prevents the effects of background temperature.
Field of view, make sure the target is larger than the spot size measured by the infrared thermometer, the smaller the target, the closer it should be. When accuracy is particularly important, make sure the target is at least 2 times the spot size.