Analysis of the Distance Coefficient of Infrared Thermometers
The distance coefficient of an infrared thermometer is determined by D: S, where D represents the distance between the thermometer probe and the target, and S represents the diameter of the light spot.
For ease of understanding, for example, using a flashlight, the beam of light from a flashlight is divergent, and the farther away it is, the larger the spot transmitted on the object. D is the distance from the flashlight to the object, S is the diameter of the light spot, and their ratio is called the distance coefficient ratio. The difference is that the infrared thermometer purely absorbs the infrared waves emitted by the object, while the flashlight emits visible light.
When using an infrared thermometer, the measured target should be filled with a field of view, usually 1.5 times the relationship.
For a fixed focal length thermometer, the focal point of the optical system is the minimum position of the light spot, and the light spot near and far from the focal point will increase, with two distance coefficients. Therefore, in order to accurately measure temperature at distances close to and far from the focal point, the size of the measured target should be greater than the size of the spot at the focal point; The zoom thermometer has a minimum focus position that can be adjusted based on 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, i.e. increasing the D: S ratio, the higher the cost of the thermometer.
The thermometer has a red laser dot that is used for target indication. Many people who are not familiar with it believe that the measured temperature is the temperature of that point, but this is actually a misconception. The temperature read is actually the average temperature of a circle with a diameter of S centered on that point. This is also why there is a difference in the temperature measured at the same point, far away and near, Because the S has changed (the distance is different, and the attenuation of infrared wave energy will also have an impact).
