Introduction of ultra-low illumination camera and infrared lamp

The ultra-low illumination camera is a hotspot product in the surveillance industry that has been launched in recent years with the development of semiconductor technology. At present, it has been widely used in the fields of finance, cultural expo, hotel, office building, residential community property management, etc. Since the traditional camera is difficult to meet the needs of 24-hour continuous monitoring (because it is impossible to turn on the lights 24 hours in any location), the new type of ultra-low illumination camera has seized this opportunity to develop rapidly.

Most ultra-low-illumination cameras use Exview HAD technology. Exview HAD CCD cameras will greatly increase the sensitivity to external light. In the near infrared region, the sensitivity can be increased to 4 times that of ordinary cameras, such as (Figure 1) . Therefore, even in a very dark environment, this camera can usually see objects that are invisible to the human eye. The emergence of this technology has been welcomed by the surveillance market, and it can show the best results in various lighting environments. , Especially with special infrared lighting equipment, you can get high-definition black and white images to achieve 0-illuminance monitoring (in the absence of light). In the near-infrared area of ​​760mm-1100mm of near-infrared, if combined with infrared illumination of appropriate wavelength, clear black and white images can be achieved.

A similar method for obtaining images under low illumination is to increase the amount of CCD exposure in a single frame image by means of a single frame charge accumulation, thereby increasing the sensitivity of the camera to a single frame image. This method can also obtain a lower illuminance index, but it needs to reduce the consistency of the image, so be careful not to use it with the gimbal when choosing this camera, otherwise it will cause the phenomenon of losing the picture. There are some other methods for obtaining images under low illumination, but none of them can fundamentally solve the problem of illumination.

In addition, pay attention to a few points when choosing to use low-illumination cameras and infrared lights.

First, the appropriate lens must be selected. In order to improve the sensitivity of the camera to infrared lights and scenery, a lens with a large amount of light should be selected as much as possible, and pay attention to the drive level value of the large aperture as much as possible when using automatic aperture or electric two variable lenses. Generally, with the increase of the focal length of the lens, its light flux will be relatively reduced. When choosing an infrared lamp, a certain margin should be left, and pay attention to the nominal index of the infrared lamp.

Second, the optional power supply of the infrared lamp should meet the minimum electrical power required as much as possible, and it often happens that the irradiation distance is not enough.

Third, the degree of reflection of the scene to be photographed must be considered. Infrared has the same characteristics as visible light such as reflection and refraction. Therefore, if there is no good reflective environment (such as buildings, walls, and signs) around the target scene, certain considerations should be given. Distance margin.