The sensor of the camera is equivalent to the human eye, but what is more powerful than the eye is that it can sense some invisible light, such as infrared light. The sensor has an index sensitivity, also known as the minimum illumination value, which can reflect the response ability to weak light. The higher the sensitivity, the stronger the light sensing ability, and the stronger the infrared sensing ability.

Because the sensor can sense infrared, in the daytime, the infrared in the light also enters the image, which will cause the overall image to be red. Therefore, ordinary cameras are pasted with filters on the sensor surface to filter out the infrared in the light. If the infrared camera is also pasted with this filter, the infrared light actively emitted by the infrared lamp of the camera at night will also be filtered out, resulting in the failure of the infrared lamp. In order to avoid this situation, high-end infrared cameras are generally equipped with double filters, that is, open the infrared filter during the day to filter out the infrared in the light, and close the infrared filter at night to let the infrared enter the sensor through the lens. This is why infrared cameras can clearly image at night when people can't see clearly.

The laser camera is composed of a semiconductor laser and a lens. The laser beam has small angle and concentrated energy, which is very suitable for long-distance lighting; With the zoom lens, the laser can follow up with the camera, so that the laser can produce corresponding changes according to the change of camera focal length.

Compared with infrared light, laser lighting can ignore the intensity of light. Through laser components and ultra-low illumination photosensitive elements, the camera can realize long-distance HD monitoring in a completely dark environment to ensure imaging clarity; Secondly, it has a long service life. The service life of laser monitoring camera is three times that of ordinary infrared camera, which has more advantages for the application of 24-hour monitoring engineering; Moreover, the traditional infrared camera has a large heat dissipation, which not only needs to consume more power, but also the heat will accumulate in the fuselage, causing the fuselage to overheat, which will seriously affect the service life of camera electronic components, while the laser camera does not have this hidden danger. However, laser lighting also has the defect that the beam is too concentrated. In medium and short-distance monitoring, it has no advantage over infrared due to insufficient cost and coverage angle. Therefore, it is mainly used for long-distance monitoring applications, such as scenic spots, railways, etc.

In addition, in some scenes with less strict requirements for light, white light can be always bright or stroboscopic fill light can also be used to obtain better monitoring engineering effect. White light lamp is a new type of energy-saving and environment-friendly green lighting lamp. It is a kind of visible light and belongs to a cold light source. Its biggest feature is that its imaging at night is color. The scenery seen is not much different from that during the day. It can provide more information and is conducive to investigation and evidence collection. Cameras with white lights are usually used in bayonet systems in road monitoring projects or entrances and exits of community parking lots.