Why should I calibrate fiber optic test and splicing equipment?

Would you drive a car with a speedometer that gives you faulty readings? How can you tell how fast you were driving? Optical testing equipment that is out of calibration will also cause faulty test readings. A fusion splicer that is out of calibration will produce inferior splices. False readings from an OTDR and a poor connector splice joining cable will cost you time and money. Not to mention customers and network owners who would question your fiber optic installation work. How do you expect to evaluate your installation or repair with equipment that has not been calibrated?

As demand keeps growing, more and more of today’s fiber optic network owners are demanding that their networks handle the increased speed needed to keep up with those demands. This means that your splice equipment and cleaver need to be up to the job. With this increased need for speed, today’s loss budgets are lower than ever. These budgets need to be met. Test equipment must be more accurate than ever.

Items that need to be calibrated

You need to remember your OTDR is an important piece of diagnostic equipment. It must be calibrated at specific intervals to ensure correct diagnostics. A power meter & light source is another important piece of testing equipment in your arsenal. This tool consists of transmitter and receiver. It measures the power of an optical signal that is passed through the fiber cable. When two ends of optical fiber are permanently welded together by an electrical arc, this is known as a fusion splice. Arc calibration is a must for the proper splice to take place. Do not forget the optical fiber cleaver. Cleaving is the process of breaking or cutting of the fiber. A fusion splice requires the use of a highly accurate cleaver. As you can see the each piece of equipment mentioned has a specific job. Not calibrating a cleaver or a fusion splicer can mean a poor splice. Without calibration, optic test equipment such as the OTDR and power meter & light source are somewhat useless in determining things like the quality of connectors and splices.

What is a loss budget?

This calculation is the total optical power loss that the system is allowed to have. This amount is determined by the power losses resulting from the total amount of equipment that the system has. A loss budget for fiber optic networks is derived from installation of items such as patch cords; couplers, adaptors, splices, cable and any additional optical components installed in the system. This is determined when the network is designed. After it is installed this loss must be tested to see if the budget has been met. Is the splice that has been made to extend the cable acceptable? How about a connector? Was it installed properly? Another equally important reason for OTDR testing, is once the system is active, later on if a problem presents itself, you can go back to the original test. You could then compare the new test to the original test and determine the problem quickly and easily. This is why accurate OTDR testing equipment must be maintained. In order for that piece of equipment to be accurate it must be calibrated on a regular basis.

Calibration is not an option. It is a must.

Put calibration off and it could cost you more than the cost of the calibration itself. Incorrect readings could have technicians thinking the installation is better than it really is or just the opposite. Your company name depends on quality and accuracy. It is not worth saving a few bucks on calibration. During the year your equipment such as splicing equipment is subjected to all sorts of events that can cause it to go out of calibration. If you are in the south heat can be your enemy. Up north freezing temperatures are not your friend. Have you left your equipment in your truck only to be bounced around? All those bumps, drops and bangs add up to inaccurate readings. Dirty conditions are no help either. In many instances in order to get paid you need up to date certified testing equipment. If you are certified for ISO 9001 you need your equipment calibrated. ISO clause 7/6 reads in part as; Control of monitoring and measuring equipment. The organization shall determine the monitoring and measurement to be undertaken and the monitoring and measuring equipment needed to provide evidence of conformity of product to determined requirements. The organization shall establish processes to ensure that monitoring and measurement can be carried out and are carried out in a manner that is consistent with the monitoring and measurement requirements. Remember, calibration is always a must when the measurements from your equipment are critical – It’s that simple.

What exactly is calibration?

When you calibrate any piece of equipment the unit to be calibrated is compared to a unit of a known value. This known value comes from another similar device of known accuracy and precision. Equipment that has a laser which is being calibrated means that laser must fall within a specific acceptable range. Should the equipment being tested be found to be “out of calibration” and produces faulty readings, the equipment must be repaired or adjusted so it falls within the acceptable specified range of measurement.

What is NIST Calibration?

NIST stands for National Institute of Standards and Technology. They provide services to make sure the equipment being calibrated is measured up to a particular piece of equipment similar to that of the equipment being calibrated. NIST certifies that that the lab testing to equipment uses a method that meets the standards of the NIST and must match the NIST measurement standard for a particular piece of equipment. For fiber optic purposes, that would be equipment such as an OTDR, a fusion splicer, cleavers, power meters and lights sources.

In simple terms when using the NIST method you need an unbroken chain of documents; your piece of equipment and components are compared to our piece of equipment which in turn was compared to a piece of equipment from the NIST which is within a stated tolerance. NIST sets the tolerance and it is correct. Our equipment was compared to the NIST equipment so we know ours is correct. Finally yours is compared to ours and found to be correct. That is an unbroken chain. This unbroken chain which is traced back to NIST standards for accurate measurement is how uniformity is maintained. Once your equipment has been tested and meets NIST standards you will receive a calibration certificate paper work stating the results and the date. This means your equipment has met the highest test standards. A big plus would be getting that certification from an ISO compliant calibration company.

What is ISO?

The International Organization for Standardization (ISO) is the world’s largest non-governmental organization developer of standards. ISO 9001 is the most sought-after and internationally acclaimed management system standard. They have created over 22,808 International standards and goals. Their standards are voluntary. Companies who seek out this standard are ensuring that their customer requirements are met accurately and consistently. When it comes to calibration a company is working to meet a set of regulatory requirements which in turn will improve company performance, which will improve product and service quality. This method in the end will benefit the customer by assuring them that the ISO certified company has met the exacting ISO standards to bring them a better product.


Over time even a well cared for piece of test equipment can lose its’ accuracy. You must have your equipment calibrated as suggested by the manufacturer. However, in many instances you may need to get it done sooner, as many conditions that the equipment is subjected to may alter or falsify your test results. As networks need to increase their efficiencies loss budgets are becoming smaller and smaller. Only calibrated equipment can assure you are correctly within that budget. Calibration is not really an option. It is a must. Always use a lab that will test to NIST standards and if possible use an ISO certified test lab. Accurate results will always save you time, money and your company reputation.

Author: Fiber-MART.COM

eShop of Fiber Optic Network, Fiber Cables & Tools

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