Fiber Cleaning Tips
In the field of testing and construction, there is a famous proverb: there is no problem that cannot be solved by wiping the fiber once, if there is, it is wiped twice.
The end face of the fiber jumper is the flat section at the end of the connector with different shapes and structures at both ends of the fiber jumper.
It can be known from the optical principle that this will increase the attenuation of optical signals and cause network failures. For example, during a network troubleshooting process with intermittent packet loss, when an OTDR was used to check the optical path status, it was found that the attenuation of the intermediate jump point of one of the cores was very large, reaching 2.2db at a wavelength of 1300mm. After inspection, the abnormal attenuation at this place is caused by the unclean end face of the optical fiber jumper. After cleaning, the optical path attenuation value returns to normal, and the OTDR test is successfully passed. The intermittent packet loss phenomenon of the original fault disappears, and the network communication returns to normal.
Through the above fault cases, we can fully understand the importance of the cleanness of the fiber end face. In the daily operation and maintenance of the optical path, the operating specifications should be strictly implemented to ensure the cleanliness of the end face of the fiber jumper. If the fiber end face is contaminated, it should be cleaned according to the standard procedure. Let's talk about how to check the cleanliness and cleaning methods of the end face of fiber jumpers.
1 Inspection method of end face dirt
After disconnecting the device, pick up the optical fiber jumper and face the light, and check whether the end face is clean and smooth by observing whether the refraction of the end face to the light is bright. Through observation, if the reflection of light on the end face is smooth and bright, it is considered to be relatively clean. If the reflection of light on the end face is not bright and smooth enough, it is likely that there is dirt or scratches on the end face. The end face will seriously affect the quality of light transmission. Of course, checking the end face with the help of the instrument can more comprehensively understand the details of the end face.
At present, there are many inspection tools and instruments for fiber end face, among which fiber microscope is the most widely used professional inspection instrument. In general, a fiber optic microscope for multimode shows a magnification of 200 times, while a fiber microscope for single mode shows a magnification of 400 times.
2 End face dirt cleaning method
●Clean the end face without the assistance of professional tools
In the case of no tool assistance, you need to prepare anhydrous alcohol, cleaning cotton balls, and lens paper. The cleaning steps are as follows.
(1) Hold the cleaning cotton ball in one hand, and then drop anhydrous alcohol on the cotton ball. The alcohol should not be dripped too much.
(2) Wipe the end face in the same direction with a cotton ball with anhydrous alcohol, and the number of times depends on the degree of dirt on the end face.
(3) Wipe the end face that has been wiped with alcohol on the lens paper folded more than 3 layers in the same direction until the alcohol is completely dry and the end face is refracted with dazzling reflections.
(4) Carefully check the light reflection at each part of the end face and whether there is any fiber debris left on the end face. If necessary, repeat the above steps 1 to 3 until the end face is clean and flawless.
●Clean the end face with the assistance of professional tools
At present, there are many manufacturers producing professional optical fiber end face cleaning tools, including optical fiber cleaning cloth, optical fiber cleaning card, optical fiber cleaning pen, cleaning gas, etc., which are very easy to carry and use. The specific use steps are as follows.
a, contact cleaning method
(1) Clean paper or clean cloth
Wipe the end face of the optical fiber connector with lint-free paper or lint-free cloth and anhydrous alcohol. The dust-free paper is made of virgin wood pulp with special processing technology, ultra-low dust, pure texture, efficient water absorption, fine paper, and will not scratch the surface of the object to be wiped. The non-woven fabric is strong and soft, does not produce lint, does not contain any chemical impurities, does not cause allergic reactions, and is not easy to fluff and fall. This method is characterized by simple operation and low cost, but the effect is general.
(2) Cassette cleaner
The appearance of the cassette cleaner is like the "tape" of the early VCR, it uses a special wiping tape in a roll, which is installed in a reelable casing, because its principle is to use strong adhesive to stick the dirt on the end face of the connector. , so there is no need for alcohol and every cleaning is very effective. The disadvantage is that sometimes the adhesive itself will remain on the end face of the connector, and the adhesive tape is a consumable, the wiped place cannot be reused, and the cost is high.
(3) Special cleaning stick (pen)
Fiber-specific cleaning sticks (pen) are specially designed to clean the inside of fiber-optic adapters, or to clean the hard-to-reach ferrule end faces inside the adapter. It's shaped like a pen with one end that goes inside the adapter's ceramic sleeve. The working principle is either the cotton swab plus anhydrous alcohol method, or the strong viscose method. There are two common specifications: 1.25mm and 2.5mm. 1.25mm is used for cleaning LC type connectors, and 2.5mm is used for cleaning FC/SC/ST connectors.
b, non-contact cleaning method
(1) Ultrasonic cleaning method
Anyone who has been engaged in optical fiber ferrule grinding knows that there is an "ultrasonic cleaning" process after the optical fiber connector is polished to clean the glue and dirt on the end face of the ferrule. Now there are portable ultrasonic cleaners on the market. Its principle is not much different from other ultrasonic cleaning methods. The key is how to turn the cleaning liquid into an ultrasonic "liquid column" in such a small space and send it to the end face of the connector. The waste liquid is recovered and sucked up in the same small space. The whole process takes more than ten seconds, and there will be no contact with the connector except where it should be cleaned, and there will be no harmful residue.
(2) High pressure blowing method
Its principle is to apply cleaning liquid on the end face of the connector, and then blow it against the end face of the connector with high pressure air. The advantage of this method is that it takes only a few seconds to do it, but it cannot be cleaned without high pressure gas. There are also some special gas cleaning tools on the market now, which are very convenient.
As for which cleaning method to choose, it is necessary to comprehensively consider the performance requirements of the product, the site environment, and the cost spent. On the premise of meeting the performance requirements of the system, choose the most cost-effective method.