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Please find below technical information,
that should help you come to an informed
decision as to which product supplied by
Auriga is best for your needs.
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Fibre Termination Methods.
There are many methods for terminating fibre optic cables. Choosing the right method depends on application, engineers experience, cost and also personal preference. Here is an outline of the most popular methods.
Epoxy Polish.
The original fibre termination process which involves gluing the connector onto the fibre and then polishing the connector end face to achieve a good finish. Either heat cure or anaerobic cold cure epoxy can be used and almost all available connector styles can be terminated with this method. Epoxy polish connectors can also be fitted to the widest variety of fibre from 250µm up to 3mm jacketed fibre and are able to withstand many diverse environmental conditions making epoxy polish a very robust and versatile termination method. However, although not difficult to terminate, some training is required and they are more suited to the high volume user with a stable work force as it is experienced engineers that consistently provide the best termination. Probably the cheapest method once an initial set of tools has been purchased as connectors tend to cost pence as opposed to pounds with the required consumables, epoxy, polishing papers (or lapping films) etc. also being very in-expensive. You can acquire everything you need in kits like the OPT-HEATKIT and OPT-COLDKIT. Provide a very low-loss termination.
Pre-Loaded Epoxy – 3M Hot Melt.
3M Hot Melt is a widely used fibre termination method that uses a connector pre-loaded with adhesive providing a convenient and fast termination. Connectors still require polishing so some degree of training is required but this is a far simpler method for polishing connectors, requiring fewer consumables. If a mistake is made during termination then the epoxy can be re-heated in order for the fibre to be re-positioned reducing the amount of scrapped connectors. Connectors are slightly more expensive but consumable costs are reduced with fewer connector styles available and generally only suitable for 900µm and 2/3mm jacket fibres. Provide a low-loss termination.
Crimp.
With this termination method, connectors are crimped onto the fibre and then polished to achieve the desired finish. This style of termination is very quick and can be performed by in-experienced engineers. Designed to be used almost anywhere, no power is needed and with systems like the 3M Crimplok performance meets the requirements of TIA 568B standards.
Crimp – No Polish.
This is by far the easiest and fastest method for terminating connectors onto fibres. The termination is performed by crimping the fibre into a connector which has a pre-polished stub of fibre in the ferrule eliminating the need for any polishing. Only a few simple tools are required and engineers can become proficient at terminating in a very short period of time. Kits are available from Tyco Electronics in the form of their Lightcrimp+ system and from 3M with their No Polish Connector (NPC). No consumables or power are required and the termination can be carried out almost any where including confined spaces. Well suited for companies performing a limited amount of fibre terminations with no dedicated fibre engineers. Only the most common connectors are available and they tend to be very expensive. However, when all installation costs are taken in to consideration, due to the speed with which they can be terminated, costs per installed connector may be cheaper.
Mechanical Splice.
Normally used for quick fix repairs and temporary installations, mechanical splices are used for joining two fibres together. Very simple to use requiring few tools and almost no training, two cleaved fibres are mated together in a clamping device to complete the termination. Splices can usually be re-used but cost is very high. Some methods, like 3M Fibrlok, use a jig to help in the termination, others like Tyco Electronics Corelink system is more of a manual process.
Fusion Splice.
Fusion splicers are used to join fibre cables together or connect ‘pigtails’, normally a 1/1.5m length of buffered fibre factory terminated with a connector for minimum loss, to provide the least possible loss within a fibre optic infrastructure. Most modern fusion splicers, like those from Furukawa, are fully automatic, providing an excellent loss with minimal fibre preparation, therefore requiring very little training for the engineer. Probably the best method for terminating singlemode fibres due to the exceptionally low losses that are required. Most machines are portable and light weight and can be battery operated enabling them to be used in the field. The best fusion splicers use a core to core alignment system which physically aligns the core of the fibre ensuring minimal loss during the termination process. Cladding alignment is the next most common method, but as it aligns the 125µm cladding of the fibres, a higher loss should be expected. Fusion splicers are very expensive costing several thousand ponds so they are really only practical for those terminating fibre everyday, however, hiring them for individual jobs could prove very cost effective.
Fibre Testing Methods.
Fibre testing is an essential part of the installation process and should always be carried out to ensure the quality of the installation. It tends to be a much simpler process than testing copper networks as there are really only two parameters that are a concern. These are insertion loss for multimode installations and insertion loss and return loss for singlemode installations. Another very important aspect is cleaning. It is a well known fact that most failures in fibre optic systems are caused by dirt. A good cleaning and inspection process will remove this problem.
Following is a guide outlining some of the test and inspection methods required to ensure you get the best from your fibre optic installation.
Inspection and Cleaning.
To inspect the end face of the connector we can either use a handheld microscope, such as a Priorspec II, or an inspection probe, similar to the EXFO FIP-400 range. This will show any dirt and damage that may affect the performance of the connector. Several methods can be used to clean the end faces, the most common being a lint free tissue and cleaning fluid, such as that available from Microcare, or a cassette style cleaner which is used dry.
Visual Fault Locator.
A visual fault locator, VFL, is the basic fibre optic tester that all installation engineers should have. It helps to ensure continuity of an installed link so an engineer can check he has installed connectors in the patch panels correctly. If a pigtail has been bent excessively or broken while being managed in a patch panel, the light from a VFL will ‘bleed’ through the 900um sheath enabling this to be rectified. The VFL is also able to highlight breaks in patchcords making this a very useful entry level tester for fibre optic links. They are also very good in helping to optimise the connection in a mechanical splice.
Light Source and Power Meter.
In order to find out how good the fibre installation is we must measure the insertion loss in dB. To do this we need a stabilised light source, which sends a prescribed quantity of light down the fibre, and then a power meter which then measures the amount that is received. A calculation is made, which may be carried out by the power meter depending on the type used, and is then compared with our loss budget to decide whether the installation will work or not! However we must know how the link is constructed to be able to calculate a loss budget and determine if the link is good or not. If we cannot tell how the link is made up, number of connectors splices and length of cable, then we cannot accurately test using the light source and power meter set up and should use an OTDR.
OTDR - Optical Time Domain Reflectometer.
The OTDR operates differently to a light source and power meter by sending a pulse of light down the fibre and then measuring the reflections from any change in refractive index that occurs along the way – for example from a splice, connector or the end of the cable. It is an ideal maintenance tester as it can show you where a cable may be bent or damaged, where there are events such as connectors and splices (and give you the losses associated with each of these features). It can also tell you the length of the cable and give you the total insertion and return losses for the whole system. This is all done from one end of the cable, with no need to inspect visually for damage along the length of cable - as the equipment will tell you where any may be. This information can then be printed off in one comprehensive trace, which can be used as definitive proof of system status.