What is the Difference Between Ordinary and Infrared Cameras

1、 Why does “CMOS camera” need to add infrared fill light?

Image sensors, especially CMOS image sensors, have poor imaging effect at low illumination (i.e., dark light). The American ov7910 image sensor adopted by various manufacturers basically cannot image when the light is lower than 3Lux. When driving at night, if the external light is extremely dark, the light mainly depends on the rear light of the car. This level of light is almost powerless to image the ordinary CMOS camera.

The CMOS image sensor is very sensitive to infrared light (infrared light is the light invisible to young eyes), so an infrared light emitting lamp is added around the camera lens to emit infrared rays to the imaging object. The infrared rays reflected by the imaging object pass through the lens to form an infrared image.

The infrared light is monochromatic light, and the image formed by the infrared light is therefore a monochromatic image.

2、 Principle and composition of infrared light compensation function

The camera adds the infrared light filling function, mainly adding the following components:

1; Light sensor:

2; Infrared diode

3; Power supply and control circuit

The light sensor and the peripheral circuit can adjust and control whether the infrared lamp is turned on and the intensity of turning on by detecting the ambient light intensity, so as to realize the night vision light filling function.

3、 What is a filter?

Our daily environment light is very complex. Human eyes can only recognize and judge seven colors of light. In addition, there are many wavelengths of light, such as ultraviolet light and infrared light.

However, image sensors, especially CMOS image sensors, are very sensitive to other wavelengths of light such as infrared. In order to make the color of the imaged image realistic and form an image as seen by the human eye, an optical device (i.e. a filter) is added between the camera lens and the image sensor. The function of the device is to cut off and filter the light of other wavelength bands except the seven color light.

The camera with filter device (i.e. filter) is added, and the color is realistic and bright.

In short, the function of the filter is to filter out the infrared and other wavelengths of light in nature, so as to make the imaging image vivid and bright.

4、 Filter difference between ordinary camera and night vision camera

It is known from the above that for ordinary cameras, the color can be realistic and bright by “adding filters”. The function of the filter is to filter out infrared rays. However, for the night vision camera, the function of the infrared lamp is to increase the infrared light, so that the infrared light passes through the lens to the image sensor, so that the image can be imaged in the dark. Therefore, in the night vision camera, the filter and the infrared supplementary light are a pair of contradictions.

In order to filter out some stray light and release the infrared light of the infrared lamp, the night vision camera adopts a kind of “day and night dual-purpose filter”, which must be able to release the infrared light of one-step sub-band, so that the infrared light can pass through at night. However, in the daytime, because of this function, unwanted stray light is allowed to pass through, so the color is white in the daytime and the color is poor.