Fibre Optic / Laser Safety with Single Mode Fibre
G'day guys, Have been doing a bit of research in the area of Laser Safety, we're looking at buying some new continuity-type testers for fibre (Model is OVF-1 Visible Fault Locator, as I gather it - A google gave me http://www.butlertech.ie/products/pdfs/ovf1.pdf) and one issue that was raised was that of safety when looking down a fibre line. Especially given that some of our newer technicians particularly, are OK with networking hardware but have relatively low levels of experience with Fibre. So in the interests of safety and best practise i'm looking at what kit we should have to safely troubleshoot fibre runs at a basic level (eg, validate continuity of a fibre run / clearly identify what goes where. Not talking full fibre loss analysis or anything at this stage - initial solution is for our computer techs, not our cabling specialists.). Multimode stuff is less of an issue, being LED driven, but Single Mode is a different can of worms, especially given that its often outside the visible spectrum. What do the players on here use? Laser filter goggles or somesuch I presume? Any brands or types reccomended / preferred? Of course due care should be taken to make sure theres no active laser emmitters on the other end of the feed, but beyond that, nice to be protected. Recommendations from the floor? Cheers Mark. (All thoughts/comments are in my personal opinion, this is largely a personal enquiry i'm making off my own bat, out of interest...)
On Wed, 26 Jul 2006, Mark Foster wrote:
Have been doing a bit of research in the area of Laser Safety, we're looking at buying some new continuity-type testers for fibre (Model is OVF-1 Visible Fault Locator, as I gather it - A google gave me http://www.butlertech.ie/products/pdfs/ovf1.pdf) and one issue that was raised was that of safety when looking down a fibre line. Especially given that some of our newer technicians particularly, are OK with networking hardware but have relatively low levels of experience with Fibre.
I believe the traditional approach is to have a sign which states "Do not look into laser with remaining eye." JSR
John S Russell wrote:
I believe the traditional approach is to have a sign which states "Do not look into laser with remaining eye."
Here's a design suggestion for said sign: http://www.astro.umd.edu/~bjw/software/ -- Juha Saarinen www.geekzone.co.nz/juha | Skype: juha_saarinen www.computerworld.co.nz | MSN: juha_saarinen(a)msn.com Voice: +64 9 974 4948
John S Russell wrote:
On Wed, 26 Jul 2006, Mark Foster wrote:
Have been doing a bit of research in the area of Laser Safety, we're looking at buying some new continuity-type testers for fibre (Model is OVF-1 Visible Fault Locator, as I gather it - A google gave me http://www.butlertech.ie/products/pdfs/ovf1.pdf) and one issue that was raised was that of safety when looking down a fibre line. Especially given that some of our newer technicians particularly, are OK with networking hardware but have relatively low levels of experience with Fibre.
I believe the traditional approach is to have a sign which states "Do not look into laser with remaining eye."
JSR
I believe this anecdotal story can help in that department: http://www.skull.co.nz/omm/
On Wednesday 26 July 2006 12:38, Mark Foster wrote: Hi Mark,
What do the players on here use? Laser filter goggles or somesuch I presume? Any brands or types reccomended / preferred?
Of course due care should be taken to make sure theres no active laser emmitters on the other end of the feed, but beyond that, nice to be protected. Recommendations from the floor?
As JSR said, "do not look into laser with remaining good eye". A few months ago I actually had an engineer from a well known systems integrator tell me that the long-haul single mode link we were working on couldn't possibly be working because he couldn't see any light coming out of his end of the fibre. He honestly thought the system used visible frequency light and had looked down the patch lead for it. I've never seen people working on fibre using goggles or anything like that. Basic common sense seems to serve. Never, ever, look into a fibre with or without a scope unless you can directly see both ends of it. Never connect a light source to a fibre unless you know what is going on at the other end. Use light meters to test levels, if you suspect a fibre is dirty clean it and retest with a light meter rather than scoping it if you can't see both ends of the lead. Beware of highly reflective surfaces when handling live fibres. Always, always, cap the ends of leads and the in/outputs of GBICs as soon as they are disconnected. This helps keep crap out of the connections as well as keeping things safe. Don't assume that because a port is administratively disabled or has no link that it isn't emitting. We have kit that never turns off the lasers, regardless of the state of the link, which came as a surprise when we encountered it. There is a little bit of info, primarily aimed at lab kit here: http://www.clf.rl.ac.uk/reports/lasersafety/sc1.htm#8.4 The ITU apparently have some published best practice documents, but I don't know what they are. -- Al http://where.else.net.nz
On Wed, Jul 26, 2006 at 01:55:02PM +1200, Al Muckart said:
On Wednesday 26 July 2006 12:38, Mark Foster wrote:
Of course due care should be taken to make sure theres no active laser emmitters on the other end of the feed, but beyond that, nice to be protected. Recommendations from the floor?
I've never seen people working on fibre using goggles or anything like that. Basic common sense seems to serve.
Our fibre guy here notes: -- With the power levels we are using goggles are not required. Our guys are trained not to stare at the end of a fibre but not withstanding that the power level is such that no issues should occur. Like with a class 1M laser (equivalent of the old Class 3A) even with a safety factor of 10 it is stated you would have to stare at the fibre end from a distance of 150mm for over 100 seconds (haven't checked those figures so it is something like that) before there was a chance of damage to the eye. This is not a natural thing to do. Our lasers are in the lower end of Class 1M However If you are using some form of magnification (ie endoscope) then you would be an idiot to stare into the fibre with out 100% confidence that that there is nothing hooked to the other end. -- Cheers Si
With the power levels we are using goggles are not required. Our guys are trained not to stare at the end of a fibre but not withstanding that the power level is such that no issues should occur.
Like with a class 1M laser (equivalent of the old Class 3A) even with a safety factor of 10 it is stated you would have to stare at the fibre end from a distance of 150mm for over 100 seconds (haven't checked those figures so it is something like that) before there was a chance of damage to the eye. This is not a natural thing to do.
Our lasers are in the lower end of Class 1M
However If you are using some form of magnification (ie endoscope) then you would be an idiot to stare into the fibre with out 100% confidence that that there is nothing hooked to the other end.
Thanks Simon. We're using mainly 1000LX and 1000SX GBIC's and MDA's which are all to my knowledge, Class 1 or Class 1M Devices. The testing that we'd expect guys on the ground to do doesn't involve endoscopes or any other form of magnification - simply a light continuity test to aid in validating end-to-end, which fibre we're dealing with and whether there is a likely physical break in the cable. Fibre in the situation i'm thinking of, is generally used for distribution between buildings in a campus environment, so we wont be seeing 1-person-seeing-both-ends situation very often. I guess then, untill such time as we see high-power laser based emitters in use on our infrastructure, that we won't have to worry about any additional protection, aside from the usual 'don't be a goon and stare at the fibre ends' advice given. Cheers all. Mark. PS: The 'other eye' advice is well taken. =)
participants (6)
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Al Muckart -
John S Russell -
Juha Saarinen -
Justin Cook -
Mark Foster -
Simon Blake