Differences between infrared thermal imagers and night vision systems
1、 Image intensifier night vision system
In terms of classification, night vision devices can be divided into two categories: image intensifier tube night vision devices (traditional night vision devices) and infrared night vision Thermographic camera.
Ordinary infrared night vision devices, which are active night vision devices, require light to be present in the target, so they are traditionally called low light night vision devices. Their principle is to amplify the weak light of the target into light that can be observed by the human eye through its internal core component, the image intensifier tube. In the case of total darkness, no target can be seen, so this type of night vision device is equipped with an infrared transmitter, which uses invisible infrared lights to illuminate the target and make it visible.
According to the algebra of image intensifiers, night vision devices can be divided into one to four generations. Due to the inability of the first generation night vision system to meet people's needs in image brightness enhancement and clarity. So it is rare to see first generation and first generation+night vision devices abroad. If you want to achieve true use, you need to purchase a second-generation or higher image intensifier night vision device. In traditional second-generation and above night vision devices, the well-known brands are ORPHA and ASI. These two brands share a common background in developing top-notch night vision products with the US and NATO military.
2、 Infrared night vision Thermographic camera
Basically, thermal imaging night vision devices are called passive night vision devices. The passive thermal imaging night vision device uses infrared detector, optical imaging objective lens and optical mechanical scanning system (optical mechanical scanning system is omitted in the current advanced focal plane technology) to receive the infrared radiation energy distribution of the measured target and reflect it on the photosensitive element of the infrared detector, There is an opto mechanical scanning mechanism (the focal plane thermal imager does not have this mechanism) to scan the infrared thermal imager of the measured object, and focus on the unit or spectral detector. The detector converts the infrared Radiant energy into electrical signals, which are amplified and converted into standard video signals. The infrared thermal image is displayed on the television screen or monitor. This thermal imaging night vision device observes the target exactly the same in full darkness and during the day, and is not affected by light.
At the end of last century, with the development of thermal imaging technology, the U.S. military gradually began to equip infrared night vision Thermographic camera due to the technical advantages of thermal imaging technology over traditional night vision devices. The infrared night vision Thermographic camera has been permanently developed in the past 10 years, and the cooperation between RNO and the US military has also promoted the development of infrared night vision Thermographic camera in civilian use. RNO, a well-known military enterprise in the United States, can be said to have contributed immensely.
3、 The difference between night vision equipment and thermal imaging equipment
1. Effectiveness
1) If you have used an ordinary night vision device, you will find that the observation feeling of the night vision device is completely different from that of the ordinary infrared Thermographic camera. This is because a typical night vision instrument observes the target directly through the lens, so the field of view is circular, similar to what a telescope lens sees, and the image is green. If the clarity is sufficient, it is possible to identify who the character's target is and see the person's facial features clearly.
2) The infrared night vision Thermographic camera sees the image on the internal LCD screen rather than the target directly, so the field of view is square. The imaging of the infrared night vision Thermographic camera will be based on the temperature distribution. The higher the temperature, the greater the brightness. On the contrary, the lower the temperature, the darker the color. The main purpose is to find targets and identify target categories, such as people and animals.
2. The influence of light factors
1) The second-generation+night vision system is greatly affected by the environment due to its imaging principle. Especially under the influence of light, when the light becomes dim, the observation distance will be shortened. In the case of complete darkness, auxiliary infrared light sources must be used, and the distance of the auxiliary infrared light source can generally only reach up to 100 meters. At the same time, they also fear strong light, although many traditional night vision devices have strong light protection. However, if the ambient brightness changes significantly, it will have a significant impact on the observation.
2) Infrared thermal imaging night vision devices are not affected by light. Whether it is day or night, or rainy, snowy, or foggy days, the target object can be clearly observed. For this reason, the top vehicle night vision devices, such as Mercedes Benz and BMW, all use infrared Thermographic camera.
