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PacketStar
®
PSAX 1-Port Channelized OC-3/STM-1 CES Module User Guide , Issue 1 Release 11.0.0
255-700-714R11.0 B-1
B
Laser Safety Information
Overview of this Appendix
This appendix provides precautions on the safe use of optical modules, and
specifications on the snap-on connector (SC) duplex single mode transceiver
used in the 1-Port Channelized OC-3/STM-1 CES single-mode module, and
general information on lasers.
General Laser Information
Optical fiber telecommunication systems, their associated test sets, and simi-
lar operating systems use semiconductor laser transmitters that emit infrared
(IR) light at wavelengths between approximately 800 nanometers (nm) and
1600 nm. The emitted light is above the red end of the visible spectrum,
which is normally not visible to the human eye. Although radiant energy at
near-IR wavelengths is officially designated invisible, some people can see
the shorter wavelength energy even at power levels several orders of magni-
tude below any that have been shown to cause injury to the eye.
Conventional lasers can produce an intense beam of monochromatic light.
The term monochromaticity means a single wavelength output of pure color
that may be visible or invisible to the eye. A conventional laser produces a
small-size beam of light, and because the beam size is small, the power den-
sity (also called irradiance) is very high. Consequently, lasers and laser prod-
ucts are subject to federal and applicable state regulations as well as interna-
tional standards for their safe operation.
A conventional laser beam expands very little over distance, or is said to be
very well collimated. Thus, conventional laser irradiance remains relatively
constant over distance. However, lasers used in lightwave systems have a
large beam divergence, typically 10 to 20 degrees. Here, irradiance obeys the
inverse square law (doubling the distance reduces the irradiance by a factor
of 4) and rapidly decreases over distance.
Lasers and Eye Damage
The optical energy emitted by laser and high-radiance LEDs in the 400–1400
nm range may cause eye damage if absorbed by the retina. When a beam of
light enters the eye, the eye magnifies and focuses the energy on the retina
magnifying the irradiance. The irradiance of the energy that reaches the ret-
ina is approximately 10
5
or 100,000 times that at the cornea and, if suffi-
ciently intense, may cause a retinal burn.
The damage mechanism at the wavelengths used in telecommunications is
thermal in origin (i.e., damage caused by heating). Therefore, a specific
amount of energy is required for a definite time to heat an area of retinal tis-