Analysis of the Infrared Thermometer's Distance Coefficient
The distance coefficient of the infrared thermometer is determined by D:S, D represents the distance between the probe of the thermometer and the target, and S represents the diameter of the spot.
For ease of understanding, use a flashlight as an example. The beam of the flashlight is divergent, and the farther away it is, the larger the spot on the object will be. D is the distance from the flashlight to the object, S is the diameter of the spot, and their ratio is called the distance coefficient ratio. The difference is that the infrared thermometer purely absorbs the infrared waves radiated by the object, while the flashlight emits visible light.
When using an infrared thermometer, the target to be measured should fill the field of view, usually 1.5 times the relationship.
For a pyrometer with a fixed focal length, the focal point of the optical system is the minimum spot position, and the spot will increase near and far from the focal point, and there are two distance coefficients. Therefore, in order to accurately measure temperature at a distance close to and far from the focus, the size of the measured target should be larger than the spot size at the focus; the zoom thermometer has a minimum focus position, which can be adjusted according to the distance to the target.
If the thermometer must be installed far away from the target due to environmental conditions, and to measure small targets, a high optical resolution thermometer should be selected. The higher the optical resolution, the higher the D:S ratio. The cost of the thermometer is also higher.
There is a red laser point on the thermometer, which is used for target indication. Many people who don’t know where it is, think that the measured temperature is the temperature at that point. In fact, this is a misunderstanding. The temperature read is actually based on that point. The point is the center of the circle, the average temperature of a circle with a diameter of S, which is why the temperature measured at the same point is different when it is far away and close to it, because the S has changed (the distance is different, the energy of the infrared wave Attenuation also plays a role).
