Fiber Optical cable safety

Remember the last time you looked into your company's safety plan with a view to finding items related to
working with fiber in it?

Do not remember? This is not surprising, because in many organizations safety precautions when working with optical cables do not pay due attention.

Consider several aspects of safety when working with optical fiber: the classification of radiation sources according to their degree of danger to eyesight, methods of working with optical fibers and the use of chemicals.

As a result of the development of the industry for many years, we have several types of radiation sources of different power, operating at well-defined wavelengths (see table). Three types of fiber optic systems are used: LEDs, conventional lasers, and vertical-cavity laser (Vertical-Cavity Surface-Emitting Laser - VCSEL). There are several options for these three types of devices: lasers with a Fabry-Perot resonator and distributed feedback, as well as surface and end radiation LEDs. In addition, amplifiers are widely used to amplify optical signals, including Semiconductor Optical Amplifier (SOA) and more common amplifiers based on the Erbium-Doped Fiber Amplifier (EDFA).

Table: Sources of radiation used in telecommunications.
Note. Some lasers, including the VCSEL type, are listed with two classes at once since they exist in versions with different powers and for different applications. If in doubt, choose a more powerful Class 3 laser.

In North America, the main standard issued by the American Institute of Laser (Laser Institute of America) in 1988, which defines safety measures when working with optical cable systems, is ANSI Z136.2. (see “Classification of laser radiation sources according to their degree of danger to eyesight”).

Radiation detection.

Among the instruments used to detect radiation, the most common are optical power meters. They contain photodetectors, with the help of which the radiation power of various wavelengths is measured. In addition, other devices are also used - photosensor cards that respond to infrared radiation incident upon them with appropriate electronic activation, and infrared vision devices that convert infrared radiation with wavelengths of 800 and 1300 nm into visible light. Using the latter, the power characteristics of radiation sources are usually determined.

Specialists dealing with optical data transmission technology must be guided by the rule that any fiber can be active. Therefore, you should never look into the outlet of the transmitter or into the end of the connector.

For inspection of elements of optical cable systems, the most common instrument is a microscope. It is clear that it allows you to explore the surface of the fiber end, but is not able to detect the infrared radiation emanating from it. To control the quality of fiber surface treatment, microscopes with a magnification of 200-400 times are suitable. Usually, a laser filter is built into them to protect the eyes, attenuating the radiation level by 2–35 dB depending on the wavelength. Microscopes with filters are somewhat more expensive than conventional microscopes but safer. Always use precisely such microscopes in your work and, before ordering them, study the specification of each of them.
Also read: fiber optics jobs
Cheaper microscopes, with a magnification of 30-100 times, which are equipped with many kits for installing optical cable systems, often do not have filters at all. When working with them, the probability of accidental eye damage is high. Therefore, such devices are not recommended to be used either to control the quality of fiber processing or to verify compliance with safety requirements. In any case, when working with such a microscope, the user should always wear glasses that protect the eyes from laser radiation.