Do you know the application of infrared light?

Infrared, also known as infrared radiation, is a kind of "light invisible to human eyes". The application of infrared is very extensive. The common applications are as follows:

In daily life, many household appliances cannot do without remote control. Many household appliances are equipped with infrared remote control device. When the remote control and the infrared receiving port line up, the left and right deviation is not more than 15 ° The effect is the best.

Now more and more electronic devices are equipped with infrared ports to support wireless transmission and avoid the burden of cable connection. If you use infrared, you can access the Internet through your mobile phone.

The use of infrared can also prevent theft. It is composed of an infrared transmitter and an infrared receiver. The infrared beam emitted by the infrared transmitter forms an invisible blockade line. When someone passes through or blocks the infrared, the receiver will start the alarm host, and the alarm host will send an alarm immediately after receiving the signal. 

Infrared switch. There are active and passive infrared switches. The active infrared switch consists of an infrared transmitting tube and a receiving tube. When the receiving tube receives the infrared emitted by the transmitting tube, the lamp is turned off; When the human body blocks the infrared ray, the light turns on. The passive infrared switch takes the human body as the infrared source (the temperature of the human body is usually higher than the ambient temperature). When the infrared radiation is detected, turn on the lamp.

Use infrared photography. According to the test, in the natural light radiation, the infrared ray can reach more than 40%. In black-and-white photography, the visible light can be blocked by using a special filter from red to dark red to make the infrared image sensitive on the film. In the specific operation, the focus should be adjusted first and then the filter should be added. In addition, the normal exposure should be obtained by trial shooting. So what's the reason for infrared photography? Analysis of the brightest objects, such as blue water and sky, can not reflect more infrared light. Although the imaging of ordinary black-and-white film is normal, the infrared film shows a darker color. And trees and grasslands because of chlorophyll can reflect a large number of infrared and white, in order to achieve surreal artistic conception. Infrared ray not only provides a special creative technique for photography, but also has a high transmittance, so it can be used to take a clear picture in fog and smoke. It is often used for exploration and military reconnaissance in scientific research. The infrared ray can penetrate the surface of the picture and penetrate into the interior of the pigment. It can also judge the authenticity of the famous paintings of the masters.

In the dark night, the application of infrared remote sensing equipment can detect a variety of mineral deposits. Using infrared remote sensing photos, geothermal resources and radioactive mineral resources were investigated in China.

In the military field, infrared can also play an important role, the more typical are infrared reconnaissance and infrared guidance. The infrared imaging equipment carried by the reconnaissance satellite can obtain more intelligence information of ground targets, identify camouflaged targets and monitor ground military operations at night; The missile early warning satellite can detect the infrared radiation of the engine plume when the missile is launched and give an alarm by using the infrared detector, which provides a certain early warning time for intercepting the incoming missile. Infrared guidance is to use the infrared radiation of the target itself to guide the missile to approach the target automatically to improve the hit rate.

In recent years, infrared has been widely used in military, satellite, industry, health and scientific research, so the problem of infrared pollution also arises. Infrared is a kind of heat radiation, which can cause high temperature damage to human body. Strong infrared rays can cause skin damage, which is similar to scald. First it is burning pain, then it is burn. There are several different cases of infrared damage to the eyes. The infrared with wavelength of 7500-13000 angstrom has higher transmittance to the cornea, which can cause damage to the fundus and retina. Especially, the infrared ray near 11000 angstrom can protect the anterior media (corneal lens, etc.) of the eye from damage and directly cause retinal burn. Almost all infrared rays with wavelength above 19000 angstrom are absorbed by the cornea, which will cause corneal burn (haze and leukoplakia). Most of the energy of infra-red with wavelength over 14000 angstrom is absorbed by cornea and intraocular fluid, and cannot penetrate iris. Only the infrared below 13000 angstroms can penetrate the iris, causing damage to the iris. Long term exposure to infrared rays may cause cataract. Therefore, when we use infrared, we should also keep enough vigilance against its harm.