Four Problems of Infrared Camera Night Vision Surveillance System
October 20, 2022
Focus offset problem
Due to different wavelengths of visible light and infrared light, the imaging focus is not on one plane, resulting in clear images under visible light conditions during the day, blurring under nighttime infrared light conditions, or clear images under nighttime infrared light conditions, and image blurring under daytime visible light conditions. It can be solved in three ways. First, the use of automatic focusing integrated camera; second, the use of IR special focus does not shift the lens; third, the use of professional adjustment tools, under the existing lens conditions can also be achieved without offset.
Color problem
All black and white cameras are infrared-sensitive. Infrared light is a stray light for a color camera under visible light conditions, which will degrade the sharpness and color reproduction of the color camera. The filter of the color camera is to prevent infrared rays from participating in imaging. There are two ways to make the color camera sense infrared light. First, switch the filter to block the infrared light from entering under visible light; remove the filter under the condition of no visible light and let the infrared light enter. The image quality is good, but the cost is high and the switching mechanism will cause a certain failure rate. Second, opening a specific infrared channel on the filter allows infrared rays with the same wavelength as the IR lamp to come in. This method does not increase the cost, but the color reproduction is slightly worse.
The problem of sensitivity
Camera sensitivity is a core part of infrared night vision monitoring. The better the sensitivity, the stronger the ability to sense infrared rays. Of course, the better the sensitivity, the more expensive the camera is. In general, an infrared night vision system within 50 meters is better if a camera with 0.1 lux is used; a night vision system with a range of 50 meters to 100 meters should use a camera with 0.01 lux; a night vision system with a distance of 100 meters or more should be 0.001 lux. Above the camera. Of course, as the sensitivity increases, the price of the camera will increase significantly.
Of course, like many other products, the phenomenon of camera imaginary indicators is particularly serious. I once took a 0.1 lux camera and a camera with a nominal 0.0001 lux for comparison. The latter was not as good as the former. More camera manufacturers artificially improve the signal strength, the sensitivity is very good, but the signal-to-noise ratio is very poor, resulting in a lot of night images "snow spots" a lot.
The problem of distance
One hundred people will have a standard infrared night vision distance for infrared products. I think it should be based on the effectiveness of the customer's application. What is the customer's standard? It is to see people! What are the "visual distances" and "discovery distances" are all ambiguous. The matching of cameras and lenses in different grades may cause the sensitivity of the light emitted from the same infrared lamp to be many times different, and the visual distance may also be much different. Therefore, it is unscientific to say how many meters a concrete infrared light is. A working distance of an infrared lamp can only be determined by matching the camera and lens of a certain quality. Also, because of the different environments in which the applications are applied, the effects will be very different and it is best to leave a certain margin.
