Infrared in the military, artificial satellites, as well as industry, health, scientific research and other aspects of the application of the increasingly widespread, so the infrared pollution problem also arose. Infrared is a kind of thermal radiation, the human body can cause high-temperature damage. Stronger infrared rays can cause skin injuries similar to burns, initially burning pain and then causing burns.
There are several different kinds of infrared damage to the eye. Infrared rays with wavelengths of 7,500 to 13,000 angstroms have a high transmittance rate to the cornea of the eye, which can cause damage to the retina at the bottom of the eye. Especially near 11000? infrared, can make the front of the eye medium (corneal crystals, etc.) is not damaged and directly caused by the fundus retinal burns.
Infrared light with a wavelength of 19,000? or more is almost entirely absorbed by the cornea, causing corneal burns (clouding, white spots). Infrared wavelengths greater than 14000 ?, the energy of the vast majority of the cornea and intraocular fluid is absorbed, not through the iris. Only infrared rays below 13,000 angstroms can penetrate the iris and cause iris damage. Long-term exposure of the human eye to infrared light may cause cataracts.
Infrared rays can be created artificially and are widely present in nature, and can also be generated during the welding process, jeopardizing the health of the welder's eyes; general organisms radiate infrared rays, and the macroscopic effect embodied in them is heat.
Expanded Information:
Heat arises when the particles that make up matter move in an irregular fashion. This motion also radiates electromagnetic waves, most of which are infrared.
1. It is true that sunlight is almost absent at night, but all matter on earth radiates infrared, some strongly and some calmly. Infrared photography is by receiving infrared rays emitted by various substances and then showing them, but it is not itself by emitting infrared rays to take pictures.
2. Infrared perspective and night vision are utilizing different properties of infrared light. Night vision is because the human eye can not see infrared light, but specially designed cameras and night-vision devices are specialized in receiving infrared light, so there will be a darkness we feel, but the camera can shoot things, because in fact everywhere is infrared light, for infrared cameras and night vision devices is a bright.
Transparency, on the other hand, takes advantage of the fact that infrared light has a longer wavelength than visible light, and can pass through fabrics (such as cotton blends and nylons) that visible light can't pass through, so with some selective filtering, you can get an image of what's behind those fabrics.
Baidu Encyclopedia - Infrared Light