Bs En 60825-2

[Florio Bessinger]

IEC60825-2:2021 provides requirements and specific guidance for the safe operation and maintenance of optical fibre communication systems (OFCSs). In these systems, optical power is possibly accessible outside the confines of the transmitting equipment and/or at great distance from the optical source.

This document requires the assessment of hazard level at each accessible location of the OFCS as a replacement for product classification according to IEC 60825-1. It applies to the installed OFCS as an engineered, end-to-end assembly for the generation, transfer and receipt of optical radiation arising from lasers, light-emitting diodes (LEDs) or optical amplifiers, in which the transference is by means of optical fibre for communication and/or control purposes.

Individual components and subassemblies that fall under the definition of a laser product are subject to the applicable subclause(s) of IEC 60825-1. This document is applicable to individual components and subassemblies intended to be installed within OFCSs.

This site uses cookies to deliver services such as remembering your shopping cart contents and tracking page visits for "audience measurement" purposes.

By using our site, you acknowledge that you have read and understand our Privacy Policy, including our Use of Cookies section, our Terms and Conditions, and our Purchasing Policies. Your use of this website and its services is subject to these policies and terms.

There is much lively debate about what useful distance range to expect when using a visual fault locator (VFL) for testing singlemode fiber installations. In this article I will provide my perspective and with it, a methodical analysis.

These days 650-nm high-power VFLs are inexpensive and readily available, so legislation related to laser eye safety is the primary limit on power levels. We assume the widely accepted IEC 60825-2:2011 Safety of Laser Products Part 2: Safety of Optical Fibre Communications Systems (OFCS).

Using different safety standards does not yield very different VFL performance results, as we will find out. However, failing to comply with local occupational health and safety standards exposes organizations to malpractice and bad corporate image-quite apart from possible eye damage, which could be to a child if that child picks up an unsafe VFL that was accidentally left behind on a work site. With broader fiber deployment, it is no longer safe to assume that a VFL will always be used in a restricted work environment.

Laser safety is determined by the maximum possible VFL emission, with no coupled fiber. With pen-style VFLs, this is a specific safety issue because of the very short fiber stub-or lack of a fiber stub at all-in these units. The uncoupled emission is often about 6 dB higher than the fiber-coupled emission quoted on the specification.

Because of this issue with uncoupled VFL eye safety, a well-designed instrument-style VFL can go about 6 dB (or 1 km) farther than a pen-style VFL that lacks a fiber stub, for the same eye-safety rating.

Fiber attenuation-This is always going to be an uncertain factor. The chart in this article, from fiber-optics.info, shows a spread of values. Based on the graph, the very likely values in the 650-nm window (which is just off the graph to the left) would be 5 to 7 dB/km. Note that loss for typical fiber is not usually specified for operation at this wavelength.

Additionally, we at Kingfisher measured a 10-kilometer drum of fiber made in the year 2000 and got a 6.3 dB/km measurement. So we will use 6 dB/km as our baseline. Previous tests produced quite similar results. Note this is many times the loss at, for example, 1310 nm, so this light cannot go very far.

Eye sensitivity-This seemed quite consistent among a number of people. The most significant variations relate to ambient light, plastic pigments in cables, what people are trying to do, and exactly how they do it.

In strong ambient sunlight, light often cannot be seen leaking through the side of the fiber bend at all, so using a VFL for fault-finding in daylight may not produce a useful result. We conducted our tests in a typical office environment with fluorescent lighting. We either used just this fluorescent lighting, or cupped our hands over the fiber to provide reasonable shade.

This procedure raises some interesting points. For example, trying to conduct fault finding on outside plant cabling would benefit from having a hut over the expected problem area to provide shade. If trying to find a fault indoors, it is helpful to turn down the lighting.

In 2014 the most recent version of the standard came out. This revised how pulse lasers were handled as well as introducing the new Class 1C. In addition the Condition 2 measurement of 70 mm was removed and now the closest distance for measurement is the Naked Eye condition (condition 3) at 100 mm

Where a product fails to meet the desired classification due to minor failures, we will issue a classification conditional upon making listed changes (such as labelling, user information and minor engineering changes). Where a retest is required this will normally be carried out at a reduced fee.

To avoid this scenario we recommend that you get us involved at an early stage in the design process to advise you on the desirable class of your product and ensure that it is designed to meet the requirements of that class.

Manufacturers can self certify their equipment to EN 60825-1, but the standard is highly complex and difficult to interpret and in many cases an expert is required to obtain the correct laser Class for the product. In any case many manufacturers prefer to have independent verification of their compliance with the classification requirements.

In Europe, product conformity is achieved by requiring manufacturers to certify to the applicable standards for their product. The onus is on the manufacturer to identify the relevant standards, design the product accordingly, and make a declaration of conformity in the user instructions. It is then the responsibility of the various national enforcement bodies to detect non-conformances and intervene where necessary. The standards are set by committees of experts and are under under continual review and enhancement. This system places considerable responsibility and trust in the hands of the manufacturers, but allows standards to be kept up to date with changing technology, knowledge and current practice.

The situation in the USA is somewhat different for laser products. Product safety in the USA is controlled by Federal Regulations which are enforced by the Food & Drug Administration (FDA), and in the case of laser products by a division of the FDA known as the Center for Devices and Radiological Health (CDRH). The Federal Regulations are written into law and manufacturers are legally obliged to comply with them. They are also legally obliged to register the products with the FDA prior to selling or importing them into the country.

The regulation controlling laser products is known as 21 CFR 1040.10. This regulation was written into law in the 1970s and has been unchanged ever since. Consequently it is now very out of date. Nevertheless it still applies and until recently all laser products sold in the USA had to conform to this regulation.

IEC 60825-1, IEC 60825-2 and IEC 60825-12 are currently identical to the corresponding EN standards (although the EU standards agencies reserve the right to vary from them if considered necessary for safety reasons). These standards are applicable in Japan, Australia, Canada and pretty much every other country not already covered.

Some of these systems have problems of their own, in particular the current monitoring. Lasers exhibit a fairly large change in lasing threshold with temperature and because the optical output/current drive characteristic is usually steep, fairly precise control of current is required. Independent optical monitoring and shutdown is probably one of the most used methods and is considered the best arrangement as this covers the case very effectively where the power creeps up due to contamination of the monitoring diode or partial failure of a component as well as a catastrophic failure.

This is just an indication of some of the methods which may be employed to comply with the single fault requirement in IEC/EN60825-1. Lasermet will act as consultants if required, providing advice on specific applications, applicability of a given design and particular information concerning the likely problems with each system.

If some of the information/items requested above is/are not supplied it may take considerable time to analyse the circuit which may result in extra test costs being charged. In some cases it may be impossible to classify the equipment without all the applicable samples/information listed above.

Consequently we strongly advise manufacturers to consider their drive electronics very carefully to ensure that the reasonably foreseeable single fault failure requirement has been covered. Otherwise serious problems are likely to arise at the testing stage, which is usually when manufacturers are under pressure to get the product on sale.

Comparison of Afterimage Formation and Temporary Visual Acuity Disturbance after Exposure with Relatively Low Irradiance Levels of Laser and LED Light

Authors:

Hans-Dieter Reidenbach, Cologne University of Applied Sciences ; Koeln Germany

Presented at ILSC 2009

The employer in the European Union has to determine in a risk assessment according to the European Directive on Artificial Optical Radiation whether workers might be exposed above the exposure limit values, which are based on the respective ICNIRP guidelines. In addition, he shall give particular attention to any indirect effects amongst others such as temporary blinding.

In order to obtain more information on transient effects, which a...

Do We Over-state the Risk of Multiple Pulsed Exposures?

Authors:

David Sliney, David H. Sliney, Ph.D., Consulting Medical Physicist; Fallston MD USA

David Lund, US Army Medical Research Detachment; San Antonio TX USA

Presented at ILSC 2009

Laser safety standards committees have struggled for years to adequately formulate a sound method for treating repetitive-pulse laser exposures. Safety standards for lamps and LEDs have ignored this issue because averaged irradiance appeared to adequately treat the issue for large retinal image sizes and skin exposures. Several authors in recent meetings have questioned the current approach of three conditions as still not sufficient to treat ...

3a8082e126