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Ultraviolet rays are electromagnetic waves that are ubiquitous and imperceptible to the eyes. Ultraviolet（Wikipedia） rays are divided into four bands according to wavelength: UVA, UVB, UVC, and UVD. This article mainly takes you to understand UVA, UVB, UVC and their respective application fields.
Long-wave UVA, with a wavelength between 320-400nm. It has strong penetrating power, can penetrate glass, even 9 feet of water; and UVA exists in all seasons, whether it is sunny or rainy.
Damage to the human body: More than 95% of the uv rays exposed to the skin are UVA, so it is the most harmful to the skin. UVA can attack the dermis through the epidermis, causing serious damage to the collagen and elastin in the skin; and the dermal cells have poor self-protection ability, and a small amount of UVA can cause great damage.
It can also activate tyrosinase, deposit melanin, form new melanin, darken the skin and age, so UVA is also called aging rays.
Some special glues and inks can be cured quickly under the irradiation of UVA ultraviolet rays. UVA ultraviolet rays can be used in areas such as shadowless adhesive curing, UV ink curing, and product surface coating.
UV LED light curing applications include UV adhesive curing in display, electronic medical, instrumentation and other industries;
UV coating curing in building materials, furniture, home appliances, automobiles and other industries;
UV ink curing in printing, packaging and other industries.
On medical devices, the current LED UV light source system can cure the solvent-free UV glue in a few seconds, so that the medical device can form a consistent and repetitive bond during the assembly process.
(2) Flaw detection
The ultraviolet lamp is combined with fluorescent agent to check the cracks on the metal surface. It can also check the leakage of air valve, car engine and car air conditioner.
Laboratory research, such as plant protein, fluorescent GFP.
(4) Identify true and false
Special ink is used when making banknotes, which can only be seen under ultraviolet light;
UV LED can help identify natural gemstones and synthetic gemstones, different types of gemstones, different colors of the same gemstone, and different color rendering mechanisms of the same color gemstones have different UV-visible absorption spectra;
Ultraviolet rays can also be anti-counterfeiting. In order to prevent counterfeit and inferior products, some special products will be marked with special marks of the company. These marks can only be found under ultraviolet rays.
Medium-wave UVB, the wavelength is between 275-320 nanometers. The penetrating power is medium, the shorter wavelength band of UVB will be absorbed by transparent glass, most of the UVB in sunlight is absorbed by the ozone layer, and only less than 2% of the part can reach the surface of the earth.
Damage to the human body: It will oxidize the protective lipid layer of the epidermis and dry the skin; further, it will denature the nucleic acid and protein in the epidermal cells, causing symptoms such as acute dermatitis (ie sunburn). If exposed for a long time, it is easy to cause skin cancer.
(1) Medical field
Skin treatment: An important application of the UVB band is the treatment of skin diseases. Scientists have found that ultraviolet rays with a wavelength of about 310nm have a strong dark spot effect on the skin, which can accelerate skin metabolism and improve skin growth, which can effectively treat pityriasis rosea, polymorphic sun eruption, chronic actinic dermatitis, Light-induced prurigo and other photo-induced skin diseases.
(2) Animal and plant growth supplement light
Because UVB ultraviolet lamps may promote the metabolism of minerals and the formation of vitamin D in the body, they are also made into growth lights to promote the growth of animals and plants.
Short-wave UVC with a wavelength between 200-275 nanometers. Its penetrating ability is the weakest, unable to penetrate most transparent glass and plastics. The short-wave uv raycontained in the sunlight are almost completely absorbed by the ozone layer before reaching the ground.
Damage to human body: The UVC in nature is almost completely absorbed by the ozone layer before it reaches the ground, and there is almost no harm to the human body. If it is direct radiation, short-wave ultraviolet rays are very harmful to the human body. Short-term radiation can burn the skin, and long-term or high-intensity radiation can cause skin cancer.
Due to the short wavelength and high energy of UVC band ultraviolet rays, it can destroy the molecular structure of DNA or RNA in microbial organisms (bacteria, viruses, spores and other pathogens) in a short time, and the cells cannot be regenerated , Bacteria and viruses lose the ability to replicate themselves. So UVC band products can be used for sterilization and disinfection of water and air.
Since the UVC belongs to the solar-blind ultraviolet band, it also has important applications in the military.
1) Ultraviolet (UV) communication: Ultraviolet communication is a new communication method with great development potential. It has many advantages that conventional communication methods do not have, such as low eavesdropping rate, high anti-interference, low bit resolution, all-weather work, etc.
2）Ultraviolet (UV) interference: The key to ultraviolet interference is to study the strong enough ultraviolet radiation, and install it to make an interference bomb with ultraviolet interference capability.
3）Ultraviolet (UV) warning: The ultraviolet alarm detects the target by detecting the ultraviolet radiation in the tail flame.
Ultraviolet photolysis oxidation oil fume purification system is currently the domestic advanced photolysis oxidation oil fume purification system. Ultraviolet rays are combined with the grease and odor in the kitchen air to decompose macromolecular organic matter into water and carbon dioxide, without secondary pollution, reducing fire hazards.
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