What are the main considerations when choosing an infrared thermometer
1) In terms of performance indicators, such as:
Temperature measurement range: Each model of thermometer has its own specific temperature measurement range, which should not be too narrow or too wide. Generally speaking, the narrower the temperature measurement range, the higher the resolution of the output signal for monitoring temperature, and the accuracy and reliability are easy to solve. The temperature measurement range is too wide, which will reduce the temperature measurement accuracy
Working wavelength: According to the blackbody radiation law, the change in radiation energy caused by temperature in the short wavelength of the spectrum will exceed the change in radiation energy caused by emissivity error. Therefore, when measuring temperature, it is advisable to choose short wavelength as much as possible, but emissivity factors must also be considered in conjunction with the detected object.
Spot size: The area of the measuring point of the thermometer is called the "spot size". In order to obtain a temperature reading, the distance between the thermometer and the test target must have an appropriate range. The farther away from the target, the larger the spot size. Therefore, in applications, attention should be paid to the ratio of distance to spot size, also known as D: S. When determining the measurement distance, attention should be paid to ensuring that the target diameter is equal to or greater than the size of the measured light point. If the target is smaller than the size of the measured light point, the thermometer will simultaneously measure the temperature of the background object, thereby reducing the accuracy of the reading.
The distance coefficient (optical resolution) is determined by the ratio of D: S, which is the ratio of the distance D between the thermometer probe and the target to the diameter of the light spot. If the thermometer must be installed far away from the target due to environmental limitations and needs to measure small targets, a high optical resolution thermometer should be selected. The higher the optical resolution, the greater the D: S ratio. If the thermometer is far away from the target and the target is small, a thermometer with a high distance coefficient should be selected. For a fixed focal length thermometer, the spot at the focal point of the optical system is small, and the spot near and far from the focal point will increase. There are 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 small focal point position that can be adjusted based on the distance to the target. Increasing D: S reduces the received energy. Without increasing the receiving aperture, it is difficult to increase the distance coefficient D: S.
In terms of environment and working conditions
Protecting attachments: The environmental conditions in which the thermometer is located have a significant impact on the measurement results. If not properly addressed, it will affect the temperature measurement accuracy and even cause damage. When the ambient temperature is high and there is dust, smoke, and steam present, accessories such as protective sleeves, water cooling, air cooling systems, and air blowers provided by the manufacturer can be selected. These attachments can effectively address environmental impacts and protect the thermometer, achieving accurate temperature measurement. When smoke, dust, or other particles reduce the measurement energy signal under noise, electromagnetic field, vibration, or difficult to access environmental conditions, or other harsh conditions, it is more suitable to choose a fiber optic dual color thermometer.
Window material: In sealed or hazardous material applications (such as containers or vacuum boxes), the thermometer needs to be observed through the window. The window material must have sufficient strength and be able to pass through the working wavelength range of the thermometer used. It is also necessary to determine whether the operator needs to observe through the window, so appropriate installation positions and window materials should be selected to avoid mutual interference. In low-temperature measurement applications, Ge or Si materials are usually used as windows, which are opaque to visible light and cannot be observed by the human eye through the window. If the operator needs to observe the target through a window, optical materials that transmit both infrared radiation and visible light, such as ZnSe or BaF2, should be used as window materials.
(3) Other options include simple operation, convenient use, maintenance and calibration performance, and price.
For example, a portable infrared thermometer is a small, lightweight, and portable instrument that integrates temperature measurement and display output. It can display temperature and output various temperature information on the display panel, and some can also be operated through remote control or computer software programs.
