Like picture 1, the end face of the optical fiber or connector shall be no pollution or defect. Common pollution and defect types include dust, dirt, pits and debris as well as scratches(Picture 2). In addition, there are many different pollution sources, such as testing equipment, dust cap, bulkhead, people and environment, etc. Once the device is contaminated, there will be cross contamination between the network connector and the port. Thus, inspecting and cleaning test ports and leads before testing network connectors prevents cross-contamination.

Picture 1. End surface free of any contamination or defects

Optical fiber inspection
Optical fiber inspection is suggested to carry out before mating connectors and using optical transceiver. As picture 3 shown, we must inspect and ensure the end surface is clean. If it is not clean, a cleaning process must be carried out. We will introduce the end face inspection of connectors and optical transceivers in the following contents.

Tools for optical fiber inspection
※ Clean, resealable container for the endcaps
※ Fiber optic inspection microscopes
※ Bulkhead probe
There are many kinds of optical fiber microscope, It was a simple, inexpensive, portable microscope. Nowadays, the most commonly used types of optical fiber inspection microscopes are video fiber optic microscope (desktop) and hand-held fiber optic microscope. (Picture 4)

Optical fiber connector inspection steps
※ Make sure that the lasers are turned off before you begin the inspection. (Warning: Invisible laser radiation might be emitted from disconnected fibers or connectors. Do not stare into beams or view directly with optical instruments.)
※ Remove the protective cap and store it in a clean resealable container.
※ Verify the style of connector you inspect and put the appropriate inspection adapter or probe on your equipment.
※ Insert the fiber connector into the fiber optic microscope adapter, and adjust the focus ring so that you see a clear end surface image.
※ Or, place the tip of the hand-held probe into the bulkhead connector and adjust the focus as picture 5.

Picture 5. Hand-held probe inserted into a bulkhead connection.
※ On the video monitor, verify that there is no contamination present on the connector end face. Here you can see the sample images of contamination conditions in picture 6.

Picture 6. Sample Images of Contamination Conditions

※ If the end face is not clean, to clean the end face and reinspect. Immediately plug the clean connector into the mating clean connector in order to reduce the risk of recontamination.

End face inspection of optical transceiver in our company
From production to delivery, the module must go through one step - cleaning port. This step will be done by the end face detector and cleaning pen.(Picture 7)

Cleaning steps
※ Turn on the cleaning instrument;
※ Insert the module into the end face detector, and adjust the focus ring so that you see a clear end surface image;
※ Through observation, check whether the end face of the module is dirty;
※ If the end face is not clean, clean the end face and reinspect. If clean, immediately plug the dust cap, to reduce the risk of recontamination.

Optical fiber connector is an important component of fiber optic network, but they must be handled properly. In order to ensure the fiber connection work with high performance, it is necessary to keep fiber and connectors end face clean. This can be easily achieved with active inspection and cleaning. For inspection, we must use the proper inspection tools and strictly observe the each steps of inspection.