Basic knowledge of sunglasses: eye the main characteristics and performance of radiation damage
Sunglasses in addition to can reduce the radiation intensity of visible light, can also reduce the ultraviolet and infrared radiation. Polarized sunglasses can also be used to eliminate the water, snow, reflecting the gravel road surface level. Sunglasses cash more endowed with fashionable breath. But the fundamental role of sunglasses is to provide radiation protection for the eyes. This article will mainly introduce the eyes are the main characteristics and performance of radiation injury of ultraviolet radiation damage to the human eye. Radiation damage to the human eye is mainly near ultraviolet, visible light and near infrared. Out in addition to the radiation comes from nature, and there are many from artificial light. Uv damage to the human eye based on the biological effects of different, uv radiation can be divided into three bands: (1) uva rays, UVA or UV - A, near ultraviolet) : wavelength at 315 nm to 380 nm, accounts for about 8% of the total all the light into the surface of the earth, can make the skin, can cause the increase of the melanin particles in epidermis cells, and can cause some fluorescent material, easy to cause cataracts. (2) the uvb rays ( UVB rays or UV - B) : wavelength at 280 nm to 315 nm, accounts for about 2% toward the surface of the earth all the light general, can make the skin red spot, easy cause keratitis, and dose correlation with human skin cancer. UVB rays accounted for just 3% to the table in the ultraviolet (uv) radiation, has a large biological effects. (3) short wave ultraviolet ( UVC or UV - C, ultraviolet) : wavelength at 100 nm to 280 nm, solar radiation, the earth this part of the ultraviolet light can be absorbed by the earth's outer atmosphere ozone completely, so the radiation is less than the earth's surface, usually there is no harm to human body. Life mainly comes from artificial ultraviolet light source, have antiseptic effect. Can also cause skin cancer. To travel to the surface of the ultraviolet radiation is restricted by many factors, such as season, latitude, altitude, climate, sunshine time, weeks surround environment on the reflectivity of ultraviolet (uv) radiation, etc. With the solar zenith Angle, ozone concentration, cloud, surface reflectivity is important. Surface ultraviolet radiation of ultraviolet radiation that is not the same as the lens. Human activities such as personal habits, length of time of outdoor activities and professional on eye ultraviolet (uv) radiation is obvious, the influence of other factors can also affect the eye ultraviolet radiation. The degree of tissue damage a dose-dependent relationship, that is, the longer the irradiation time, the greater the dose, the more serious the cause of damage.