Infrared thermometer instruments
In the production process, infrared temperature measurement technology plays an important role in product quality control and monitoring, equipment online fault diagnosis and safety protection, and energy saving. In the past 20 years, the non-contact infrared body thermometer has been developed rapidly in technology, its performance has been improved, its function has been enhanced, its varieties have been increasing and its scope of application has been expanding. Compared with the contact temperature measurement method, infrared temperature measurement has the advantages of fast response time, non-contact, safe use and long service life. The non-contact infrared thermometer includes three series: portable, on-line and scanning type. It is equipped with various options and computer software. Each series has various models and specifications. It is very important for the user to choose the right model of infrared thermometer among different types of thermometer.
Infrared thermal imager uses infrared detector, optical imaging objective lens and optical mechanical scanning system (Advanced focal plane technology omits optical mechanical scanning system) to receive the infrared radiation energy distribution pattern of the measured target and reflect it to the photosensitive element of the infrared detector. Between the optical system and the infrared detector, there is an optical mechanical scanning mechanism (the focal plane thermal imager has no such mechanism) to measure The infrared thermal image of the object is scanned and focused on the unit or spectroscopic detector. The infrared radiation energy is converted into electrical signal by the detector. After amplification, conversion or standard video signal, the infrared thermal image is displayed on the TV screen or monitor. This kind of thermal image corresponds to the thermal distribution field on the surface of the object; in essence, it is the thermal image distribution map of the infrared radiation of each part of the object to be measured. Because the signal is very weak, compared with the visible light image, there is a lack of hierarchy and three-dimensional sense. Therefore, in order to judge the infrared thermal distribution field of the measured object more effectively, some auxiliary measures are often used to increase the practical function of the instrument Can, such as image brightness, contrast control, real calibration, pseudo color rendering technology
Classification
Infrared thermal imager is a general spectrometer scanning imaging system and non scanning imaging system. The optical mechanical scanning imaging system uses unit or multi element (element number has 8, 10, 16, 23, 48, 55, 60, 120, 180 or even more) photoconductive or photovoltaic infrared detectors. When using unit detector, the speed is slow, mainly because the response time of frame amplitude is not fast enough. Multiple array detector can be used as high-speed real-time thermal imager. Non scanning imaging thermal imagers, such as the array staring imaging focal plane thermal imager introduced in recent years, belong to a new generation of thermal imaging devices, which are much better than the optical mechanical scanning thermal imagers in performance, and have the trend of gradually replacing the optical mechanical scanning thermal imagers. The key technology is that the detector is composed of a single chip integrated circuit, and the whole field of vision of the target is focused on it, and the image is clearer and more convenient to use. The instrument is very compact and light. At the same time, it has the functions of automatic focusing, image freezing, continuous amplification, point temperature, line temperature, etc., and voice annotation image. The instrument adopts PC card, and the storage capacity can be as high as 500 images.
Infrared thermal TV is a kind of infrared thermal imager. The infrared thermotv receives the infrared radiation from the surface of the measured object through the pyroelectric camera tube (PEV), and transforms the invisible thermal image of the thermal radiation distribution in the target into video signal. Therefore, the pyroelectric camera tube is the light key device of the infrared thermotv. It is a real-time imaging, and has medium resolution in wide spectrum imaging (good frequency response to 3-5 μ m and 8-14 μ m) The thermal imaging device is mainly composed of lens, target surface and electron gun. Its technical function is to focus and image the infrared radiation line of the target to the pyroelectric camera tube through the lens, and use the room temperature thermal TV detector, electron beam scanning and target surface imaging technology to achieve.
Performance
In order to obtain accurate temperature readings, the distance between the thermometer and the test target must be within the appropriate range. The so-called "spot size" is the area of the measuring point of the thermometer. The farther you are from the target, the larger the spot size. The right figure shows the ratio of distance to spot size, or D: s. On the laser sight type thermometer, the laser point is above the target center, with a 12 mm (0.47 in) offset distance.
When determining the measuring distance, the target diameter should be equal to or larger than the measured spot size. The distance between the "object 1" marked in the right figure and the measuring instrument is positive, because the size of the target is slightly larger than the measured light point. The "object No. 2" is too far away because the target is smaller than the size of the light spot to be measured, that is, the thermometer is also used to measure the background object, thus reducing the accuracy of the reading.
