1, infrared: the wavelength is between 1mm and 760 nm.
2. ultraviolet: the wavelength is 10 ~ 400 nm? The floorboard of radiation.
Second, it is found that history is different.
1. Infrared: 1800, the British scientist "William Herschel" found that the red light in the sun was surrounded by a light source invisible to the naked eye.
2. Ultraviolet rays: 180 1 German physicist Ritter discovered that a section outside the ultraviolet end of the solar spectrum can make a photographic negative containing silver bromide sensitive, thus discovering the existence of ultraviolet rays.
Third, the harm to human body is different.
1, infrared rays: intense infrared rays can cause skin damage, similar to burns, first burning pain, and then burns. In several different situations, infrared rays can hurt the eyes. The infrared ray with the wavelength of 7500 ~ 13000 A has a high transmittance to the cornea, which can cause damage to the fundus retina.
2. Ultraviolet rays: When ultraviolet rays are irradiated, the degree of damage to eyes is directly proportional to time, inversely proportional to the square of the distance from the irradiation source, and related to the projection angle of light.
The function of infrared rays
After infrared rays irradiate the body surface, one part is reflected and the other part is absorbed by the skin. The degree of skin reflection to infrared rays is related to pigmentation. When irradiated with infrared rays with a wavelength of 0.9μm, skin without pigmentation reflects about 60% of energy. Colored skin reflects about 40% energy.
When low-frequency long-wave infrared rays (wavelength 1.5μm or more) are irradiated, most of them are reflected and absorbed by superficial skin tissues, and the depth of penetration into the skin is only 0.05 ~ 2 mm, which can only act on the superficial skin tissues.
High-frequency short-wave infrared (wavelength within 1.5μm) and red near-infrared penetrate the tissue deepest, and the penetration depth can reach 10 mm, which can directly act on subcutaneous tissues such as blood vessels, lymphatic vessels and nerve endings of the skin.
In the infrared region, the band most beneficial to human body is 14μm ~ 4μm, which is collectively called "fertility light" in the medical field, because this infrared band can promote the growth of life, and this infrared ray has a good effect on activating cell tissue and blood circulation, which can improve human immunity and strengthen human metabolism.
Refer to the above? Baidu encyclopedia-ultraviolet
Refer to the above? Baidu Encyclopedia-Infrared