Principle of Infrared Thermometer

Infrared thermometers are widely used in electric power, electronics, medical treatment, equipment maintenance, fire protection, military and other fields. It is also our common instrument, but do you know its principle? The following Infrared Thermometer Suppliers will tell you how it works.

The infrared rays received from the measured object are focused on the detector by the lens through the filter. The detector generates a current or voltage signal proportional to the temperature through the integration of the radiation density of the measured object. In the electrical components connected thereafter, the temperature signal is linearized, the emissivity area is corrected, and converted into a standard The output signal. In principle, there are portable thermometers and fixed thermometers. Therefore, when choosing a suitable Infrared Thermometer for different measurement points, the following features will be the main ones:

Infrared Thermometer

1.The aiming device has this function. The measuring block or measuring point pointed by the thermometer can be seen. The aiming device can be often not needed for a large area of the object to be measured. In the case of a small object to be measured and a long measurement distance, it is recommended that the sight is equipped with a dashboard scale or laser pointer in the form of a transparent mirror.

2. Lens The lens determines the measured point of the thermometer. For large-area objects, a thermometer with a fixed focal length is generally sufficient. But when the measurement distance is far from the focus point, the image at the edge of the measurement point will be unclear. For this reason, it is better to use a zoom lens. Within the given zoom range, the thermometer can adjust the measuring distance. The latest thermometer has a zoom interchangeable lens. The near and far lenses can be replaced without calibration and recheck. 

3. The temperature of the sensor, that is, the spectral receiver, is inversely proportional to the wavelength. When the temperature of the object is low, a sensor sensitive to the long-wave spectral region is very suitable. When the temperature is high, a photoelectric sensor composed of germanium, silicon, indium-gallium, etc., which is sensitive to the short wave, will be used. When selecting the spectral sensitivity, the absorption bands of hydrogen and carbon dioxide should also be considered. Within a certain wavelength range, the so-called "atmospheric window", H2 and CO2 are almost transparent to infrared rays, so the light sensitivity of the thermometer must be within this range in order to eliminate the influence of atmospheric concentration changes When measuring thin films or glass, it is also necessary to consider that these materials are not easily penetrated within a certain wavelength. In order to avoid the measurement error caused by the background light, use a suitable sensor that only receives the surface temperature. Metal has this physical property, and the emissivity increases with the decrease of the wavelength. Based on experience, measuring the temperature of the metal is generally the shortest The measurement wavelength.

The company also provides a Portable Infrared Thermometer, if necessary, please feel free to contact us