Welcome to Laser Pointer Forums - discuss green laser pointers, blue laser pointers, and all types of lasers



Laser Pointer Store

Visual Fault finder for Fiber optic cable

th2112

New member
Joined
Nov 18, 2018
Messages
1
Likes
0
Points
1
Hello all,
I came across this site and was hoping someone could point me in the right direction. I am in need of a Visual Fault finder that can be used to troubleshoot fiber optic cable a long distance. I have several different types of these all red in color. They work well to identify fiber that is not terminated to something, but seem to have a relativity short distance they are effective. Usually about 3 to 5 miles is about all they are good for. The tool I have say they are about 10mw up to 30mw ( so they claim). Would it be possible to build something high powered that could be used to identify fiber say at 20 or 30 miles or more without burning through the fiber optic glass? I have used the smaller ones to see rodent chews in cable before, but it has to be very dark and you have to be within a few hundred foot of where the damage is. The units I currently use are like the link below. Now I know a if there is a solution it will cost a lot more and not be as portable as the cheap one below.


https://www.banggood.com/30mW-Red-L...-p-1133902.html?rmmds=search&cur_warehouse=CN

Any help would be appropriated,

Thanks,
 

Immo1282

Active member
LPF Site Supporter
Joined
Sep 4, 2018
Messages
212
Likes
122
Points
43
Can you calculate the power you'll need for the distance? I.e. what's the attenuation of your fibre per unit distance?

If you can calculate the attenuation of the fibre you're trying to test, then you might be able to roughly figure out how much power you would need at one end to see the light at 20 miles? Not really my field so I'm spit-balling here but I hope you do find an answer.

It's customary here to post an introduction with a rough idea of where you are in the world as laws differ from place to place so different lasers are avaliable depending on location. Seems like you just want an answer to the one question though rather than sticking around after - so it's not a hard and fast rule...
 

RedCowboy

Well-known member
LPF Site Supporter
Joined
Jul 10, 2015
Messages
7,026
Likes
1,761
Points
113
A problem is a fault could create an eye hazard so building a higher output unit could be dangerous to anyone along the lines, this is likely why they limit them to 30mw
 

paul1598419

Well-known member
Joined
Sep 20, 2013
Messages
13,855
Likes
1,994
Points
113
Losses in these types of fiber optic cables is very low. That is why they are limited to such low powers. Higher powers are just not necessary.
 

RedCowboy

Well-known member
LPF Site Supporter
Joined
Jul 10, 2015
Messages
7,026
Likes
1,761
Points
113
Yes but if there's a severed, uncoupled ect.... could pose a hazard down the line, so I must caution against upping the power, someone else could be working at the junction box while another is checking for faults in a home/building ect... anything is possible so safety first.
 

RA_pierce

Well-known member
Joined
Sep 16, 2007
Messages
3,401
Likes
379
Points
83
A problem is a fault could create an eye hazard so building a higher output unit could be dangerous to anyone along the lines, this is likely why they limit them to 30mw
If the transmission spectrum of the optical fiber does not exclude green wavelengths, a green laser should do the job well. 520 nm diodes can easily produce 30 mW and are several times brighter than red lasers at the same power. This increases visibility and, presumably, the effective distance, while maintaining a hazard that is no greater than the fault finders you are already using. With a little work, a commercial finder can probably be modified to use a 520 nm diode.
635 nm lasers are also a bit brighter than 650 nm lasers. If the finder you're using isn't 635, you can try one that is. Using a wavelength with a higher visual brightness is the best way to go to maintain safety and increase visibility.
 

paul1598419

Well-known member
Joined
Sep 20, 2013
Messages
13,855
Likes
1,994
Points
113
I would think any break in the fiber optics that would be visible to anyone would add considerable losses to the system. Possibly to the point where you would lose you connection entirely.
 

RedCowboy

Well-known member
LPF Site Supporter
Joined
Jul 10, 2015
Messages
7,026
Likes
1,761
Points
113
I wanted to use fiber to combine laser diodes before but was told that commercial fiber was only good to refract near IR and I expected that 650-670nm red might work well enough to look for leaks but wasn't sure about green although I did see a green light fault checker pen for sale.
 




Top