Optical cable generally consists of three parts: cable core, strengthening element and sheath. The following are the three parts of the optical cable structure: (Guide: Types of optical cable) Cable core: It is composed of single or multiple optical fiber core wires, and has two structures: tight sleeve and loose sleeve. Tight-buffered fibers have two-layer and three-layer structures. (Guide: The chromatographic arrangement of the optical cable) Strengthening element: used to enhance the load that the optical cable can bear when laying. Generally metal wire or non-metal fiber. Sheath: It has the characteristics of flame-retardant, moisture-proof, pressure-resistant, and corrosion-resistant. It mainly protects the cabled optical fiber core wire. According to the laying conditions, it can be composed of aluminum tape/polyethylene integrated longitudinal tape adhesive outer protective layer (LAP), steel belt (or steel wire) armor and polyethylene protective layer.