At what power level do DWDM systems become dangerous to work near (i.e. not staring into any optics, using light meters, etc)? I never see technicians on inside DWDM systems using eye protection, but I see power levels of amps going higher and higher. On a recent meter I saw almost .6mW...
Any pointers to a document saying 1550nm becomes dangerous at xxxx dbM?
Thanks in advance,
DJ
There are erbium doped raman lasers with output of up to 10 watts
continuous wave, they are (obviously) class 4 devices and are considered
hazardous.
3r and 3b emitters shouldn't be directly exposed to the eye, and carry
an appropriate warnings. the 10-80km stuff should all be 1 or 1m and
does't merit the yellow triangle.
Deepak Jain wrote:
Hi Deepak,
Most modern DWDM transponders with 160km network side optics will
be launching anywhere from -2dBm to +2dBm depending on how warm the
laser is, assuming a +2 dBm launch you are looking at around 1.6mW -
not something you want to be exposing your eyes too. If you've also
deployed EDFA's in your optical topology potentially adding another
+20 dBm or so, its a good idea to start documenting expected optical
power levels at each point in your topology for times when splice work
or other maintenance work needs to be performed. To be on the safe
side, the best policy is to simply shut down any light contributing
lasers on a given strand when performing any kind of maintenance on
that strand (design your optical topology with redundancy in mind, so
you can seamlessly take light off a given path if need be). Modern
gear usually comes equipped with a feature called ALS (Auto Laser
Shutdown), where if an LOS condition is detected the laser is
automatically shutdown. If your gear supports this, enable it. It
could potentially save an ignorant tech's eyesight :).
Cheers,
Kevin Hodle
It might be good to note that there are ZX GBICs (120km variants) that are launching at +2 to +5, so you don't really need a DWDM system to achieve these levels. Care not to expose eyes to this light should be taken whenever handling optics of any kind.
I forget who the vendor is now, but their shelves are sealed with a door
which, when opened, turns off all the lasers on the shelf so you can
work on it, yes, a simple provisioning operation causes an outage /
protection switchover!!
Dave.
Deepak Jain wrote:
Deepak Jain <deepak@ai.net> writes:
Any pointers to a document saying 1550nm becomes dangerous at xxxx dbM?
Even -30 dBM would be pretty dangerous. You sure you don't mean dBm?
-r
Reminds me of the old warning/attention sign over a termination rack...
WARNING: Do not look into laser with remaining eye.
Jeff
It will be the last thing you never saw.
The only problem with those funny signs is they scare remote hands techs
into never looking at a fiber because they don't want to try and
understand the difference between a SX GBIC and a class 3 ultra longhaul
amp.
Honestly, that is probably better. Kinda like never pointing a gun at anyone, whether you think it is loaded or not.
Put another way: I don't trust many H&E techs to know the difference between an SX GBIC and a Buck Rogers Laser Cannon.
Besides, lots of lasers these days are infrared, so you can't see them anyway. (Hence the "last thing you never saw" comment.)
In a message written on Tue, Jun 09, 2009 at 01:06:42PM -0500, Richard A Steenbergen wrote:
The only problem with those funny signs is they scare remote hands techs
into never looking at a fiber because they don't want to try and
understand the difference between a SX GBIC and a class 3 ultra longhaul
amp.
Save your poor techs eyes, and make them more reliable all at the same
time:
Leo Bicknell wrote:
In a message written on Tue, Jun 09, 2009 at 01:06:42PM -0500, Richard A Steenbergen wrote:
The only problem with those funny signs is they scare remote hands techs into never looking at a fiber because they don't want to try and understand the difference between a SX GBIC and a class 3 ultra longhaul amp.
Save your poor techs eyes, and make them more reliable all at the same
time:
This conversation has gone places I didn't expect. Leo, that card is pretty cool, but for a few hundred $$ more, you can get a light meter (if someone is smart enough to use the card...)
Does anyone *use* any eye protection (other that not looking at the light, turning off the light etc) -- I mean like protective goggles, etc, when doing simple things like adding/removing patch cables from an SMF patch panel.
I get that if you *know* the gear you are using has a Class 3 laser on it, you should be careful... but when you are patching it into a building's cable plant and some schmuck is patching the last leg in for you (or has pulled it accidentally, etc).. um, "don't look at it" is our community's BCP?
DJ
This conversation has gone places I didn't expect. Leo, that card is
pretty cool, but for a few hundred $$ more, you can get a light meter
(if someone is smart enough to use the card...)
Now if only you could train people to use them... If I had a nickel for
every time an Equinix tech has told me I'm sending them a +67dBm signal
I'd be able to actually buy the laser to do that.
Does anyone *use* any eye protection (other that not looking at the
light, turning off the light etc) -- I mean like protective goggles,
etc, when doing simple things like adding/removing patch cables from an
SMF patch panel.I get that if you *know* the gear you are using has a Class 3 laser on
it, you should be careful... but when you are patching it into a
building's cable plant and some schmuck is patching the last leg in for
you (or has pulled it accidentally, etc).. um, "don't look at it" is our
community's BCP?
Come on, the closest thing to a dangerous laser you're going to find in
most colos is the laser pointer built in to the vendor pen schwag you
picked up at the last beer and gear. The class 3 lasers are few and far
between, and copiously labeled when you do come across them. Spend 5
minutes teaching people what the laser classes and how how to read the
label.
Deepak Jain wrote:
> Does anyone *use* any eye protection (other that not looking at the
light, turning off the light etc) -- I mean like protective goggles,
etc, when doing simple things like adding/removing patch cables from an
SMF patch panel.
There are osha requirements and ansi standards.
ANSI Z136.1 - Safe Use of Lasers
ANSI Z136.2 - Safe Use of Lasers in Optical Fiber Communication
Systems Utilizing Laser Diode and LED Sources
I get that if you *know* the gear you are using has a Class 3 laser on
it, you should be careful... but when you are patching it into a
building's cable plant and some schmuck is patching the last leg in for
you (or has pulled it accidentally, etc).. um, "don't look at it" is our
community's BCP?
Actually that's pretty much the requirement for 3r, for 3b and 4 the
requirements for eye protection and manual safety systems are much
higher. All this high power stuff is rather rare (your cisco ons for
example is a class 1 laser product), unless you terminate one end of a
submarine system you'll likely never see a class 4 laser in this context.
I tend to carry around extra dust protection boots in the tool bag to
recover the exposed sc/st plugs that seem to accumulate in panels that
people touch a lot, mostly, it protects the ends of the ferrules.
In a pinch the camera on a MacBook pro can be used to detect
presence of IR light. Here's light from a 10Gbase-LR xenpak:
http://www.majhost.com/gallery/kl/Macbook/macbook-laser-camera.jpg
It's easier to see when previewing in real time than
in the static picture but it does require careful aim.
- Kevin
Most 'cell phone' cameras also detect IR. Handy to verify that A/V equipment "Remotes" are working.
--Michael