1. The advantages of infrared pyrometer measurement

The infrared pyrometer has many advantages for non-contact temperature measurement by receiving infrared rays radiated by the measured body.
1. Use the infrared pyrometer to measure the temperature of objects that are difficult to reach or move, such as materials with poor heat transfer performance or small heat capacity.
2. The infrared pyrometer can quickly realize an effective regulation loop in a short response time.
3. Infrared pyrometer does not have parts that will wear out, so there is no continuous cost like using a thermometer. Especially for small objects to be measured, such as contact measurement, large measurement errors will occur due to the thermal conductivity of the object. Here, the infrared pyrometer can be used without any doubt, and for corrosive chemicals or sensitive surfaces, such as paint, paper and plastic rails. Through remote remote control measurement, it can be far away from the dangerous area, so that the operator is not dangerous.

2. The principle structure of the infrared pyrometer

The infrared pyrometer focuses the infrared rays received from the object to be measured on the detector through a lens through a filter. The detector generates a current or voltage signal proportional to the temperature by integrating 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 infrared pyrometers and fixed infrared pyrometers. Therefore, when choosing a suitable infrared pyrometer for different measuring points, the following features will be the main ones:

1. Sight

The sight has this function, the measuring block or measuring point pointed by the infrared pyrometer can be seen, and the sight 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 measuring 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 infrared pyrometer. For large-area objects, an infrared pyrometer 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 infrared pyrometer can adjust the measuring distance.

3. The sensor, that is, the spectral receiver

Temperature is inversely proportional to 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. Therefore, the light sensitivity of the infrared pyrometer must be within this range in order to eliminate the influence of atmospheric concentration changes. When measuring thin films or glass, it must be considered 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. The emissivity increases with the decrease of the wavelength. From experience, the infrared pyrometer measures the temperature of the metal. Select the shortest measurement wavelength.