What is Fiber-Optic Polishing?

Fiber-optic cables require clear, unobstructed transmission of light wavelengths through their networked glass cores. Connected by various fittings and jacks, it becomes necessary from time to time to troubleshoot and maintain these connections, and that includes polishing their ends. Glass fiber is a higher-maintenance medium than copper wire, requiring precision connection and fitting in order to transmit light accurately without attenuations that can be caused by flaws, gaps, and misalignments. The process of fiber-optic polishing can occur in the field or in a technical lab.

Different techniques are used for single mode and multimode fiber. Optical fibers may possess end tips with ceramic ferrules designed to connect snugly. This is to prevent back reflections and other signal losses; with a proper fitting, any reflected light can be directed back into the cladding surrounding the glass core. Fiber-optic polishing employs a range of tools and products used to create precision fits and finishes in the delicate glass ends.

These can include epoxies and adhesives that ensure immobile alignments. Hot melt techniques bake epoxied connectors in an oven, while other epoxy/polish methods glue the fiber into the connector and require polishing tips with a special film. Fittings cure overnight and can't be heated with hand tools. Quick setting, less robust anaerobic adhesives are sometimes used in place of epoxy for indoor fiber-optic polishing techniques.

Less reliable crimp and polish methods forgo adhesives in favor of squeezing the fiber with a crimp. Additionally, some manufacturers produce pre-polished splices, which are essentially polished stubs already epoxied into the ferrule, inserted as a splice into the line. This method, however, introduces more loss from multiple redundant connections and splices at each terminal.

Different techniques of fiber-optic polishing permit work using field equipment and bench equipment, depending on the maintenance needed. These jobs typically involve splicing, among other things. Polishing jobs normally require 99% isopropyl alcohol, polishing (lapping) film and pad, a polishing puck, and epoxy or adhesive. Other crimping tools and connectors are needed. Some technicians also find needle, syringe, and piano wire useful.

Eye protection is always necessary to protect against powerful industrial lasers used in long-distance single-mode networks. Supporting tools may include a visual fault locater to troubleshoot fiber faults and breaks. A fiber-optic inspection microscope permits precision analysis of hair-fine fibers. Additionally, technicians rely upon jacket strippers, cutters, cable slitters, and fusion splicers.

Like polishing wood with sandpaper, fiber-optic polishing involves similar processes; special polishing paper is employed successively from coarser grits to finer grits measured in microns. Polishing machines can increase productivity by providing rapid polishing of many different connector styles. These handheld and bench machines apply precision angles and pressures to ensure even results for optimum light transmission. They can also polish multiple connectors simultaneously. Tools must also be properly cared for in order to service the precision requirements of fiber maintenance in the lab and more challenging field conditions.