The structure of fiber optic cable is roughly the same as that of cable, but it differs from cable due to the nature of fiber optic materials and light transmission characteristics. Its characteristics are as follows:
1.fiber optic cable has a reinforcing member (tension-resistant components). Because of the small cross-sectional area of the fiber, the tensile strength is not high.
Tension is relatively small, can only withstand 400-600g of tension. In order to facilitate the construction, the fiber optic cable with a reinforcement core or tensile components that can withstand greater tension. This tension member is generally made of steel strand or nylon material, which can be in the center of the cable or in the outer sheath of the cable.
2.fiber optic cable has measures to prevent temperature changes caused by changes in the transmission characteristics of the cable.
Because the optical fiber is a glass material, its coefficient of thermal expansion and contraction than other materials in the cable to be small, the expansion coefficient of optical fiber is basically close to zero (5x10 -7/0C). When the ambient temperature drops, the other materials in the fiber optic cable shorten, while the fiber does not basically shorten, so there will be bending, the bending value of the fiber will increase. This situation is obvious below zero degrees Celsius. In addition, when the fiber is subjected to lateral pressure at a certain point, a slight bend may occur and increase the attenuation value.
3. the fiber optic cable has moisture-proof measures.
This is very important for optical fibers with long wavelength windows, because the attenuation value at 1. 31 μ m wavelength will increase when the system is damped internally. Moisture-proof methods are waterproof ointment, waterproof tape (powder) and inflatable maintenance method. When using waterproof ointment, the waterproof effect is better, but the removal of waterproof ointment when connected is difficult. The use of waterproof tape (powder), the use of waterproof tape (powder) the principle of water expansion, waterproof effect is better, there is no connection when the waterproof material removal difficulties. The use of inflatable maintenance method, because of the tight structure of the fiber optic cable gas resistance, so this cable should be inflatable conduit, is rarely used.
