One of the most important procedures in the maintenance of a fiber optic system is fiber optic cleaning. This is required to keep quality connections between fiber optic equipment. Keeping the fiber end face and ferrule on the fiber optic connectors absolutely clean is very essential. If any particles such as dust, lint or oil get on the end face, this will jeopardize the completeness of the optical signal that is being sent over the fiber.
These particles can also cause other problems such as scratching the glass surface, instability in the laser system, and a misalignment between the fiber cores. Misalignment between the fiber cores can significantly degrade the optical signal.
Steps to Follow Before Cleaning Fiber Optics
Before cleaning fiber optic connectors, make sure the cable is disconnected from both ends and turn off any laser sources. Always wear safety glasses and inspect the connectors before you clean them. Before a connection is made, the connectors have to be inspected and cleaned. A connector housing should be used for plugging or unplugging a fiber. A protective cap should be placed on unplugged fiber connectors. The unused caps can be kept in a sealed container.
When cleaning fiber optics, the end face of the connector should never be touched and also the clean area of a tissue or swab should not be touched or reused.
When using alcohol, the portion of a tissue or swab where it has been applied or the dispensing tip of an alcohol bottle should never be touched. Alcohol is flammable, so it should not be used around an open spark. Also, never leave alcohol residue on the end face because this could damage the equipment.
Cleaning Fiber Ends
The fiber end should be inspected with a fiberscope of at least 200x magnification, and if it is contaminated, it should be cleaned with the dry cleaning method.
Cle-top cleaner is recommended for the dry cleaning method. With the Cle-top cleaner, the fiber end can be cleaned with a cloth. The used cloth is then thrown away, and with just the pressing of a thumb a clean cloth will emerge. After cleaning, the fiber end should be inspected with a fiberscope. If the fiber end is still contaminated after using the dry cleaning method, repeat the process.
Inspect the connector again with the fiberscope, and if it is still contaminated, use the wet cleaning method, followed by a dry cleaning method until there is no residue.
With the wet cleaning method, an optical quality cleaning cloth and fluid are used. Even though isopropyl alcohol is frequently used as a cleaning fluid, it is slow at drying and can leave residue. Opticwipes cleaning cloth and fluid are recommended.
When using this method, dampen the cleaning cloth with the fluid and wipe the end face of the connector several times. Repeat this and then with a clean, dry area of the cloth, clean the fiber end.
The fiber should not be used if the cleaning is unsuccessful because the contamination could be due to scratching, improper polishing, or some other damage.