Visible fault location (VFL)

Use visible light to find where loss is occurring in an optical cable.


Visible Fault Locator Pen
  • Pen sized VFL fault locater & line tracer
  • Single mode, multimode and plastic fiber applications
  • Eye safe Class 1 device, no safety procedures required
  • Rugged & simple fibre optic fault finder
  • 2.5 & 1.25 mm universal connector options
  • Pulsed or continuous laser options
  • Useful in combination with an OTDR, to help exactly identify a fault

Products with integrated VFL

Products with VFL or VisiTest (2000 Series)

KI 2600 Handheld Power Meter
  • High throughput premium meter with expert features and simple interface.
  • Autotest, with up to 3 λ display
  • Powerful KITS™ standards compliant reporting software
  • Reliable, high-accuracy results
  • Rugged, slim, rubberized case
  • Large memory with text, timestamp, USB key storage
  • 1,000 hr AA battery life (or external power)
  • Sunlight-reflective high contrast backlit multi-line display
  • Detector options for all network & connector types
KI 2700 Handheld Loss Test Set
  • Versatile: LED / Laser / VFL sources and power meter in one compact Autotest unit
  • Versatile reporting / data handling options
  • USB key storage support
  • Unique and useful VisiTester option
  • Optical power meter with 1% accuracy
  • Versatile powering options
  • Large clear display
KI 2800 Handheld Source
  • Versatile: Intuitive to use, rugged & reliable
  • Mixed single mode laser / multimode LED options
  • Encircled Flux compliant
  • Unique VisiTester VFL locator option
  • Up to 6 wavelengths
  • Interchangeable connectors
  • Long alkaline / rechargeable battery life
  • Autotest
  • POF LED options
KI 9800A Series Pocket Fiber Source
  • Economical, intuitive, rugged & reliable
  • Single mode options
  • Multimode options, Encircled Flux compliant
  • VFL fault locator options
  • POF LED options
  • Multimode VCSEL options
  • Interchangeable connectors
  • Long alkaline battery life
  • Autotest

Related Fault Finders & Continuity Testers

Cold Clamp (Buried Cable Fault Locator)
  • Practical long distance fibre optic cable fault location within 1 m
  • Save days of labor for maintenance staff
  • Easily find 'invisible' optical cable faults on buried cable
  • Use on live systems

 

KI 6170 Clip-on Fiber Identifier
  • Easy to use fiber checker
  • Live fiber detector or tone detectors
  • Easy to use fiber finder
  • Supplied with interchangeable heads for most fiber/cable types
  • Low false detection rate
  • Uses popular 9 volt battery size. Auto turn-off
  • Power display is very useful for finding lossy components
  • Identifiers require a light source with tone facility, preferably 1550 nm

The useful operating range of fiber optic visual fault locators is widely misquoted, with ranges of 20, 30, 40 and even 50 Km often incorrectly stated.
This is what they will actually do. There is no magic, it's just a combination of emitted power, attenuation and eye sensitivity, combined with eye safety limits on emitted power when no connector is attached (which is often not quoted at all).

If you are struggling here, consider a different technology that's safe to use.

VFL range under ideal conditions Power level connected Power level disconnected Wavelength "Connector end view" continuity "Break location" in patch lead "Side glow" continuity Comment
KI6354 Pen -4.5 dBm - 1.5 dBm typ 650 nm 8.75 Km 5.75 Km 3.75 Km Small & easy
KI9807 -2 dBm -2 dBm 635 nm1 8.75 Km 5.75 Km 3.75 Km Brighter on short distances
KI2600 Power meter +2 dBm +2 dBm 650 nm 9.8 Km 6.8 Km 4.8 Km Top performance
KI2000 Series VisiTest +2 dBm +2 dBm 650 nm 9.8 Km 6.8 Km 4.8 Km Top performance
Class 1 Legal Limit +3 dBm +3 dBm   10 Km 7 Km 5 Km No precautions needed
KI9808 +7 dBm +7 dBm 650 nm 10.7 Km 7.7 Km 5.7 Km Requires special site precautions
Class 2M Legal Limit +10 dBm +10 dBm   11.2 Km 8.2 Km 6.2 Km Maximum legal power level allowed
Illegal VFL "20Km" +20 mW / 13 dBm Not specified! 650 nm 11.7 Km 8.7 Km 6.7 Km Illegal
Illegal VFL "30Km" +30 mW / 14.8 dBm Not specified! 650 nm 12 Km 9 Km 7 Km Illegal
Illegal VFL "40Km" +40 mW / 16 dBm Not specified! 650 nm 12.2 Km 9.2 Km 7.2 Km Illegal
Illegal VFL "50Km" +50 mW / +17 dBm Not specified! 650 nm 12.4 Km 9.4 Km 7.4 Km Illegal
Source & Clip on Identifier 0 dBm 0 dBm 1550 nm 200 Km 200 Km 200 Km Good long range solution!

Note 1: Attenuation is higher at 635 nm than at 650 nm. In addition to the photopic curve effect, this makes faults look brighter.
These calculations are approximate and variations may be observed in practice, depending on the fiber type, fiber & cable pigments, cable construction, ambient lighting, operator skill etc. 

See also: Application note 24 : How far can a VFL go?, General Optical Safety Standards, 1992 Kingfisher Introduces World's first handheld solid state VFL, FiberSafe Microscope