LFD-250B

EXFO - LFD-250B

EXFO’s LFD-250B Live Fiber Detector introduces step-motor-activated bending and makes fixed-angle bending - and the drawbacks stated above - a thing of the past.
For all fiber types and all wavelengths, insertion loss is monitored as a function of the bending angle as the motor (and not human power) moves. Although the angles differ, the behavior remains the same. The adjacent graph shows that fixed-angle bending generates excessive loss in some cases, and leads to flawed identification in others.
The LFD-250B brings a unique approach: the power loss is monitored as the motor (and not human power) changes the angle. Therefore, the angle is automatically optimized for each fiber type and each singlemode wavelength. This results in clear-cut advantages:

• Maximum loss of 1 dB guaranteed for any singlemode telecom fiber (most jacket types) and any wavelength
• No damage to the fiber: bending is always minimal and the fiber is released when no power is detected*
• Virtually 100 % reliability on traffic detection, direction identification and tone detection
• Accurate in-line, non-disruptive power measurements
• Safe to be used in long-haul applications and on high-payload fibers - contrary to traditional LFDs

EXFO’s LFD-250B performs an ambient light offset prior to fiber bending, which makes it less sensitive to ambient light. A push-down cap can also be placed on the headend to block intense ambient light.
As stated, the LFD-250B controls the insertion loss within the fiber (IL) in dB. But the absolute value of the measured signal is in dBm, so knowing the loss in dB and the power level of this light exiting, power can be measured with a better accuracy than traditional fixed loss LFDs. Of course, coupling efficiency is a factor (3 mm jackets absorb more than 1.6 mm and 900 μm jackets). However, since loss is monitored as a basis for motor positioning, the unit knows what size of jacket is being tested (either 900 μm, 1.6 mm or 3 mm), so the LFD-250B automatically uses the proper coupling efficiency parameter and computes the power within any fiber, at any wavelength, with 1 dB repeatability.

* Not optimized for use with 250 µm fibers

Key features:

• Induces minimal loss: ≤1 dB
• Detects if a fiber is active or not prior to maintenance
• Locates a particular dark fiber using tone recognition (270 Hz, 1 kHz, 2 kHz)
• Identifies traffic direction on a live fiber
• Displays the power transmitted through the fiber
• Three times faster test time (<6 s)