How to use low-light night vision and thermal imaging technology for security monitoring

    As we all know, with the development of optoelectronic information, microelectronics, network communication, digital video, multimedia technology and sensor technology, security monitoring technology is also moving from traditional analog to highly integrated digital, intelligent and networked. With the increase in market demand, modern high-tech technologies are almost all used or will be used in security monitoring systems. Among them, low-light technology and infrared thermal imaging technology have also been used in security prevention systems.

    Low-light-level night vision monitoring technology uses technologies such as electric vacuum and electronic optics to achieve the conversion of photon images, electronic images, and visible video images. During the conversion process, the electronic image enhancement technology is used to enhance the image's visibility, thereby achieving a night vision technology in weak light. Its advantage is that the visible distance is relatively long, and its disadvantage is that it cannot see objects clearly in the absence of light. That is, compared with infrared technology, this technology still requires a certain amount of light, even in a low-light environment, to see the image of the surveillance scene.

    Thermal imaging technology is a passive infrared night vision technology, while ordinary infrared monitoring technology is active infrared night vision technology. Thermal imaging technology uses the difference in infrared thermal radiation intensity of different parts of natural objects to form images. It detects targets based on the temperature difference or thermal radiation difference between the target and the background or between the various parts of the target. Since this technology does not change with the changes in the surrounding lighting conditions, it can provide video images in daytime and night, even in foggy, rainy and other harsh environments. However, it cannot achieve long-distance monitoring, and the monitoring screen can only determine whether there are suspicious people entering, but cannot clearly see the face and appearance of people.

    Ordinary infrared cameras are a kind of active infrared technology. They are a night vision technology that realizes video surveillance by actively emitting infrared light and using the target to reflect infrared light. With the application of the third-generation infrared array technology, the effect of active infrared monitoring has been greatly improved, the quality and life of the product have also improved, and the manufacturing process requirements are not high and the cost is low. It has a broad application prospect.

    Low-light-level night vision and thermal imaging technologies are somewhat similar in practical application. Cameras using these two technologies are mainly used in special surveillance locations at night that have certain requirements for the concealment of the equipment, such as military, criminal investigation, drug and smuggling control, security, etc. In such surveillance locations, these two devices are very suitable. Mark Wei of Tiandi Weiye said that low-light-level night vision cameras monitor scenes by enhancing electronic images generated by weak natural light to video images that can achieve effective surveillance. Thermal imaging technology works on the principle that objects above absolute zero (-273°C) can radiate infrared rays. Due to the different intensities of infrared thermal radiation from various objects, people, animals, and all objects in the scene can be clearly observed, and are not affected by obstacles such as smoke, fog, and grass. It can work both during the day and at night. The infrared cameras commonly mentioned nowadays are all active infrared, that is, they use infrared beams to fill in the light. The targets that can be illuminated are not restricted and they can be used in total darkness. They are effective and reasonably priced, but the fill-in light distance is limited, the concealment is not strong, and they are easily affected by factors such as weather. In addition, the reflection effects of various targets on infrared light vary greatly, all of which will affect the imaging quality.

    At present, infrared thermal imaging technology is more widely used in security than low-light imaging technology. Xue Shengyue, marketing manager of Dali, analyzed and summarized the specific applications of infrared thermal imaging as follows.

    1. Monitoring of targets at night and under adverse weather conditions

    In the pitch-dark night, surveillance equipment based on visible light can no longer work properly. If artificial lighting is used, the target is easily exposed. If a low-light night vision device is used, it also works in the visible light band and still requires weak external light for illumination. Infrared thermal imagers passively accept the infrared thermal radiation of the target itself, and can work normally regardless of day or night, and will not expose themselves. Even in harsh weather conditions such as rain and fog, the observation effect is poor due to the short wavelength of visible light and poor ability to overcome obstacles, but the wavelength of infrared light is longer, especially thermal imagers working at 8 to 14um, which have a higher ability to penetrate rain and fog, so the target can still be observed normally. Therefore, at night, especially in harsh weather conditions, infrared thermal imaging monitoring equipment can be used to monitor various targets, such as personnel and vehicles.

    2. Fire monitoring

    Since infrared thermal imagers are devices that reflect the surface temperature of objects and form images, they can be used as effective fire detection equipment in addition to being used for on-site monitoring at night. Infrared thermal imagers can quickly and effectively detect these hidden fires, accurately determine the location and scope of the fire, and find the fire point through the smoke, so as to know early, prevent early, and extinguish early.

    3. Identification of camouflaged and concealed targets

    Ordinary camouflage is mainly to prevent visible light observation. Generally, criminals usually hide in the grass and woods when committing crimes. Due to the harsh outdoor environment and human visual illusion, it is easy to make wrong judgments. Infrared thermal imaging devices passively receive the target's own thermal radiation. The temperature and infrared radiation of the human body and vehicles are generally much greater than the temperature and infrared radiation of grass and trees. Therefore, the target is not easy to camouflage or be misjudged.

    4. Application of infrared thermal imaging inspection and quarantine

    In recent years, the airport aviation business has developed rapidly, with more than a thousand passengers entering and leaving the country every day. The flow of people entering and leaving airports and ports in various countries is large, busy and crowded, and the situation is complicated. The corresponding inspection and quarantine tasks for entry and exit personnel are very heavy. At the same time, in recent years, with the prevalence and rampant epidemics of infectious diseases such as SARS and avian influenza, traditional inspection and quarantine work faces increasingly severe challenges. In order to ensure the safe and smooth customs clearance of inbound and outbound passengers under the new situation, innovative thinking and innovative means are needed. The use of an infrared body temperature monitoring system with a high degree of automation is a better technical choice.