In daily life, optical fiber is used for long-distance information transmission because the transmission loss of light in optical fiber is much lower than that of electricity in wires.
Generally, the terms optical fiber and optical cable are confused. Most optical fibers must be wrapped with several layers of protective structures before use, and the wrapped cables are called optical cables. The protective structure of the outer layer of the optical fiber can prevent the surrounding environment from damaging the optical fiber, such as water, fire and electric shock. Optical fiber can be divided into optical fiber, buffer layer and coating. Optical fiber is similar to coaxial cable, but there is no mesh shielding layer. The center is the glass core of light propagation.
In multimode fiber, the diameter of the fiber core is 1.5 μ m ~ 50 μ m, which is roughly equivalent to the thickness of human hair. The diameter of single-mode fiber core is 8 μ m ~ 10 μ m, and the core is wrapped by glass cladding with refractive index lower than the core to keep light in the core. Outside is a thin plastic coat to protect the envelope. Optical fibers are usually bundled and protected by a housing. The fiber core is usually a double-layer concentric cylinder with a small cross-sectional area, which is made of timely glass, fragile and easy to break, and needs a protective layer.
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Application of optical fiber system
At the beginning of the development of polymer optical fiber, it was only used for the control and decoration of automobile lighting. Now it is mainly used in medicine, decoration, automobiles, ships and other aspects, mainly display components. In communication and image transmission, polymer optical fiber is increasingly used in light guide, display panel, logo, switch dimming, optical sensor and so on.
Communication application
Optical fiber can be used in communication technology. 1979 September, Beijing built a 3.3km 120 optical cable communication system. A few years later, optical cable lines were laid in Shanghai, Tianjin, Wuhan and other places, and optical fibers were used for communication.
The optical cable made of multimode optical fiber can be used for communication, with good conductivity and large information transmission capacity, and one channel can accommodate dozens of people at the same time. It can simultaneously transmit dozens of TV programs for users to choose freely.
Communication using optical fiber is called optical fiber communication. A pair of metal telephone lines can only transmit more than 1000 calls at the same time, but according to theoretical calculation, a pair of optical fibers as thin as spider silk can transmit1000 billion calls at the same time! Laying 1000 km coaxial cable requires about 500 tons of copper, and it only takes a few kilograms to switch to optical fiber communication. It is contained in the sand in time, and the sand is almost inexhaustible.
Medical application
Fiber optic endoscope can be introduced into heart and ventricle to measure heart blood pressure, oxygen saturation and body temperature. The laser scalpel connected with optical fiber has been applied in clinic and can be used for the treatment of photosensitive cancer.
In addition, the endoscope made of optical fiber can help doctors check the diseases of stomach, esophagus and duodenum. Fiber optic gastroscope is a hose composed of thousands of glass fibers. It has the ability to transmit light and images, and it is soft, elastic and can be bent at will. It can be inserted into the stomach through the esophagus. Optical fiber transmits images in the stomach, so that doctors can see the situation in the stomach, and then make diagnosis and treatment according to the situation.
Sensor application
Optical fiber can send sunlight to every corner and can also be processed. Computer, robot, automobile switchboard, etc. Optical fibers have also been successfully used to transmit light sources or images. If it is combined with sensitive elements or uses its own characteristics, it can be made into various sensors to measure pressure, flow, temperature, displacement, luster, color and so on. It is also widely used in energy transmission and information transmission.
Optical fiber art application
Due to the good physical characteristics of optical fiber, optical fiber lighting and LED lighting are increasingly used for artistic decoration and beautification. The application is as follows:
The store name (standard design) and LOGO are made of thick optical fiber for halo lighting.
The local contour of the door head is illuminated by φ 18 (φ 14) edge fiber.
Optical fiber three-dimensional mirrors are used locally in the facade of the site.
The artistic distribution of optical fiber lattice is adopted, and YY-S 150 optical fiber scanner for optical fiber lighting is configured.
Arrange fiber-optic ground lights on the lawn.
Optical fiber waterfall, optical fiber stereo ball and other artistic shapes.