Fiber Optic Fusion Splicing – Arc Checking and Maintenance
Working with fiber optics takes a delicate hand and some patience. One of the most used pieces of equipment is a fusion splicer. A fusion splicer uses an electric arc to fuse two pieces of optical fiber (glass) together so that light can pass through with no scatter of light or light reflected back (backscatter) by the splice. Fusion splicing helps to reduce loss in your network. Typical loss through a fusion splice is .01dB to .05dB. When using these machines there are some important things that you need to do, as well as steps to maintain them. There are a few different types of splicers, as well as a couple of different concepts of splicing. We will discuss these and some other key points about splicing.
Different Types of Fusion Splicers
There are several different types of splicers. We have V-Groove splicers. These splicers typically only have one camera and align the fiber using the grooves that help to make sure that the cladding of both sides is matched up. These tend to be the low cost splicers which do not have sophisticated motors in them.
Then there is the active cladding alignment splicer. This type does have motors that move on the X and Y axis but it is still aligning the fibers by the cladding and not the core. These tend to be priced about a couple thousand higher than the V-Groove splicers.
Finally, you have a core alignment splicer that uses more than one camera to align your glass fibers by the core or center of your fiber. These were the first splicers that were on the market. This was due to early fiber having very poor concentricity of the core of fiber. These machines are also the most expensive of the splicers because of the advanced technology that is needed to align the fibers up by the cores.
When you are splicing, there are certain things that need to be done every time before you start splicing your fibers together. The main thing is known as an arc check. This process is to make sure that your splicer is ready and able to help you complete your job without any hiccups. Arc checking will help to make sure a fusion splicer is tuned up for environmental conditions as well as that your machine settings are ideal for you to splice. One thing that is always brought up when performing this operation, is that when doing an arc check, single mode fiber should always be used whether you are splicing multimode or single mode that splicing session. Go to your splicer’s menu and click on the “Arc Check” setting. While doing this the splicer is looking at several different factors that can play a role that affects the splicer’s performance. Weather is a big part of this. It looks at the humidity, temperature and overall performance of the machine to have the perfect formula for the conditions at your job site. This process may need to be repeated several times before your machine is ready to splice. I have heard as many as fifteen times before it was ready, but usually one or two works. So - one thing most people don’t realize is, when splicing throughout the day - as the temperature changes another arc check may need to be performed later in the day. So you start splicing at ten in the morning and it is 65 degrees. You take a break for lunch around noon. When you get back the temperature is now 75 degrees and it has become more humid. Before you start splicing, an arc check should be performed as the temperature and humidity difference will cause your splicer to not be properly ready to splice in the different conditions.
Maintenance of the Splicer
There are a couple of things that can be done with your splicer to make sure it is well maintained and running to help complete important jobs. One of the most important pieces of your splicer is the heart of your fusion splicer. That piece being the electrodes. The electrodes are a pair of conductors that electricity flows through and this is what fuses your two pieces of fiber together. The electrical arc does wear them down over a period of arcs. The recommended number of arcs before these should be changed is typically a thousand. Now, there are some others out there that are trying to extend this amount by three times this. In this case, just keep an eye on your splice losses to determine when to change the electrodes. As the splice loss estimates get higher, your machine is closer to needing the electrodes to be changed. Another key part of splicing that needs to be maintained is your precision cleaver. A cleaver is the tool that you will use to score and cut the fiber so it can make a good splice. A cleaver has a wheel that rotates - this is known as the blade. This blade wears down and also needs to be managed with a certain number of good cleaves per position on the blade. Without good maintenance of your electrodes and cleaver your equipment can shut down a job or cause problems with your splicer.
Different Methods of Splicing
When splicing, there are a couple of different reasons why you do optical fiber splicing. In the end, it is all the same concept but there are different reasons to splice. The first one is to extend a fiber cable. This is where you will splice two different lengths together. This happens when a break occurs and you will use some of the excess fiber cable originally pulled to put your link back together. This can also be in a new deployment when you need to go a greater distance over what is the max length of fiber optic cabling that can be placed on a spool. When doing the long haul applications the core alignment splicer is the recommended machine.
The next two are the same concept just a different approach. This concept is to terminate the ends of your fiber. The first one is splicing on pigtails. Pigtails are a piece of fiber that is blunt on one side and has a factory polished connector on the other end. So you are splicing fiber to fiber and putting a splice protection sleeve (a heat shrinkable tube that contains a ceramic or stainless steel strength member) on to protect the splice. These will typically require a splice tray to put your splices in to protect them. The other concept is a splice on connector. This is also a pigtail but it is a lot shorter and uses a holder that is placed in the splicer. This allows your splice protection sleeve to be covered by the connector boot and does not require any splice trays.
So remember, always arc check using single mode fiber before beginning any splicing session, whether you are splicing single mode fiber or multimode fiber that day. Maintain your fusion splicer and your precision cleaver on a regular basis and your jobs will go much smoother. A fusion splicing machine can be a tech's best friend, or his worst nightmare!
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