Optical fiber preforms are first made in the manufactur […]
Optical fiber preforms are first made in the manufacture of optical fibers. The preforms generally have a diameter of a few millimeters to several tens of millimeters (commonly known as a light bar). The internal structure of the fiber is formed in the preform, so the fabrication of the preform is the most important part of the fiber process. There are various methods for fabricating the light rod, and the commonly used production process is gas phase oxidation. In the gas phase oxidation process, the vapor of the high-purity metal halide reacts with oxygen to form oxide particles which are deposited on the surface of the glass or quartz body (or the inner wall of the tubular body) and then formed by sintering. A transparent glass rod (if it is tubular, it has to be shrunk to make it a rod shape), so that the light rod is made. At this time, the light bar already has the basic structure of the optical fiber, and the bare fiber pulled out by the wire drawing machine includes the core and the cladding. In order to protect the bare glass fiber from the contamination of external materials such as light and water vapor, some fiber types are coated with an elastic coating (coating layer) while the fiber is being drawn. The fiber consists of a core, a cladding and a coating. The light guiding portion is a solid core on the axis. The cladding serves to provide a cylindrical interface for binding the light into the core. The coating is an elastic, wear-resistant plastic material that enhances the strength and softness of the fiber.
After the fiber preform is completed, it enters the fiber drawing process. This is done by fixing the fiber preform to the top of the wire drawing machine in a clean room and gradually heating it to 2000 degrees Celsius. When the optical fiber preform is heated, it gradually melts and accumulates liquid at the bottom. When it hangs down naturally, it forms an optical fiber. This is a bit like pulling out the sugar filament when we eat the yam. The key here is the uniform heating, the control of the drawing speed, and the like. When the drawing technology is correct, the fiber structure pulled out will be the same as that of the fiber preform (just a lot smaller). The coating material is also applied in time on the wire drawing machine to protect the fiber from moisture and abrasion. Some coating materials are attached to the optical fiber by natural cooling, and some are irradiated with an optical fiber (ultraviolet light) to cure the coating material. The measurement and control of the fiber diameter is very important during the drawing process. The quality parameters such as the diameter and structure of the fiber are related to the drawing speed. The automatic measurement monitoring will adjust the drawing speed at any time.