EXFO VFL User manual

User Guide
Power Meter and VFL

ii Power Meter and VFL
Copyright © 2010–2013 EXFO Inc. All rights reserved. No part of this
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Units of Measurement
Units of measurement in this publication conform to SI standards and
practices.
Version number: 3.0.0

Contents
Power Meter and VFL iii
Contents
1 Introducing the Optional Power Meter and VFL ....................................... 1
Conventions ............................................................................................................................1
Safety Information ..................................................................................................................2
Certification Information ........................................................................................................2
2 Using the Optional Power Meters and VFL ................................................. 3
Nulling Offsets ........................................................................................................................4
Setting Thresholds and Correction Factors ..............................................................................5
Setting Reference Values on Your Power Meter ......................................................................9
Measuring Power or Insertion Loss .......................................................................................10
Saving Results Files ...............................................................................................................17
Opening Result Files .............................................................................................................18
Clearing Measurements from the Display .............................................................................19
Adding Information to Your Results ......................................................................................20
Generating Result Reports ...................................................................................................21
Identifying Fiber Faults Visually with the VFL ........................................................................23
3 Maintenance and Troubleshooting ........................................................... 25
Viewing Online Documentation ............................................................................................25
Installing a Unit You Have Purchased Separately ...................................................................25
Recalibrating the Unit ...........................................................................................................26
Contacting the Technical Support Group ..............................................................................28
Transportation ......................................................................................................................28
4 Warranty ..................................................................................................... 29
General Information .............................................................................................................29
Liability .................................................................................................................................30
Exclusions .............................................................................................................................31
Certification ..........................................................................................................................31
Service and Repairs ...............................................................................................................32
EXFO Service Centers Worldwide ..........................................................................................33
Index ................................................................................................................ 35

Power Meter and VFL 1
1 Introducing the Optional
Power Meter and VFL
Your unit can be equipped with an optical power meter to measure
absolute power (dBm or W) or insertion loss (dB). The power meter can
detect modulated signals (1 kHz, 2 kHz, 270 Hz and 330 Hz).
The built-in power meter can also include a visual fault locator (VFL) to
inspect or identify fibers.
Conventions
Before using the product described in this guide, you should understand
the following conventions:
WARNING
Indicates a potentially hazardous situation which, if not avoided,
could result in death or serious injury. Do not proceed unless you
understand and meet the required conditions.
CAUTION
Indicates a potentially hazardous situation which, if not avoided,
may result in minor or moderate injury. Do not proceed unless you
understand and meet the required conditions.
CAUTION
Indicates a potentially hazardous situation which, if not avoided,
may result in component damage. Do not proceed unless you
understand and meet the required conditions.
IMPORTANT
Refers to information about this product you should not overlook.

Introducing the Optional Power Meter and VFL
2Power Meter and VFL
Safety Information
Safety Information
The laser and electrical safety information pertaining to your unit is specific
to the unit you are using. Please refer to the corresponding user
documentation for more details.
Certification Information
The certification and declaration of conformity for your unit is specific to
the unit you are using. Please refer to the corresponding user
documentation for more details.

Power Meter and VFL 3
2 Using the Optional Power
Meters and VFL
Note: If a feature is only available for one type of power meter, it is indicated
specifically in the corresponding title or instructions.
Note: Some buttons are not available when you first access the Power Meter
application, but will be available after you tap Add for the first time or after
you open a file.
Below is a description of the Power Meter buttons and functions.
Selected wavelength
To switch between
available power meter
wavelengths
To take a new reference
measurement
Measured power or insertion loss
To switch between dB, dBm
and W as measurement units
To store a reading to the
Measurements window
To activate VFL and
change VFL mode
To perform an offset
nulling

Using the Optional Power Meters and VFL
4Power Meter and VFL
Nulling Offsets
Nulling Offsets
Temperature and humidity variations affect the performance of electronic
circuits and optical detectors, which can offset measurement results. To
compensate for this offset, the unit is equipped with an offset nulling
function.
Your unit has been designed not to require offset nulling under normal
operation, but you should perform it whenever environmental conditions
change significantly or when measuring very low power values.
To perform an offset nulling:
1. Tighten the protective cap on the power meter port.
2. From the Instrument View tab, tap Offset Nulling.
The nulling process may take a moment, depending on the type of power
meter you are using.
IMPORTANT
Light must not reach the detector when nulling offsets. Always use
an EUI or protective screw cap. Do not use a soft rubber cover.

Using the Optional Power Meters and VFL
Power Meter and VFL 5
Setting Thresholds and Correction Factors
Setting Thresholds and Correction Factors
You can define thresholds to specify acceptable power or insertion loss
values for each wavelength. Thresholds are usually supplied by system
manufacturers and depend on the system deployed.
When the measurement status is “Pass”, the value is displayed in green in
the Instrument View tab, on the Measurements list, and in reports.
When the measurement status is “Fail”, the value is displayed in white over
a red background in the Instrument View tab, on the Measurements list
and in reports.
Note: A power measurement (in dBm) will be considered as “Fail” when its value
is outside the defined absolute power threshold.
Note: An insertion loss measurement (in dB) will be considered as “Fail” when its
value is greater than the insertion loss threshold.
You must select the pass/fail status feature for the application to take into
account the defined thresholds and display the appropriate status icons. By
default, this feature is not selected.

Using the Optional Power Meters and VFL
6Power Meter and VFL
Setting Thresholds and Correction Factors
You may apply a correction factor (CF) to measured power to compensate
for inaccuracies or drifts. You should change the CF after performing an
offset nulling.
where:
Powercorrected = the corrected power value
Powermeasured = the measured power value
CF = the correction factor
For each favorite wavelength, the CF is set to 1.00 at the factory, but
allowed values range between 0.85 and 1.15.
Note: Some other products express the CF in dB, so the CF would be added to
measured power.
IMPORTANT
If you revert to factory settings, you will erase all your thresholds
and correction factors. The pass/fail status feature will be disabled
automatically.
Powercorrected Powermeasured CF=

Using the Optional Power Meters and VFL
Power Meter and VFL 7
Setting Thresholds and Correction Factors
To set thresholds or correction factors:
1. From the Instrument View tab, tap Setup, then select the
Wavelengths and Thresholds tab.
2. Select Apply thresholds (Pass/Fail status) to apply the thresholds and
display the relevant information in the Instrument View tab of the
main window.
3. From the Wavelengths list, select the wavelength for which you want
to set a threshold or a correction factor.

Using the Optional Power Meters and VFL
8Power Meter and VFL
Setting Thresholds and Correction Factors
4. Modify the thresholds or correction factor for the selected wavelength.
To apply these settings to all of the wavelengths in the list, tap Apply These
Settings to All Wavelengths.
Correction factor for
selected wavelength
To revert to
default values
To m a k e th e t h r e s h o l d
active for selected
wavelength
To select the units used for the absolute power
value (has no effect on the measurement range)

Using the Optional Power Meters and VFL
Power Meter and VFL 9
Setting Reference Values on Your Power Meter
Setting Reference Values on Your Power Meter
In Reference mode, your unit displays the loss created by the fiber under
test only, since it subtracts a reference value from the measured power.
You can set a different reference value for each wavelength. A reference
value remains in memory until a new one is stored at the same
wavelength.
If the source and power meter you are using has auto-wavelength or
auto-switching capacity, you can take the reference value automatically for
each wavelength as well.
To set reference values to use in Reference mode:
1. Check your fibers and clean them properly.
2. Using the proper adapter and test jumpers, connect a light source to
your power meter.
3. From the Instrument View tab, select the wavelength in the list.
Activate the source at the same wavelength.
OR
If you want to use the auto-wavelength or auto-switching mode, enable
it on the source, then select Auto in the wavelength list (for more
information on the auto-wavelength or auto-switching mode, see
Measuring Power or Insertion Loss on page 10).
4. Tap Reference to save the current power value as the new reference. It
will appear on the upper-right corner of the data display.

Using the Optional Power Meters and VFL
10 Power Meter and VFL
Measuring Power or Insertion Loss
Measuring Power or Insertion Loss
Measuring absolute power or link (insertion) loss is done the same way,
except for the referencing step. You can take power or insertion loss
measurements and save them for further analysis.
You can either perform measurements manually and select each
wavelength yourself, or you can use the auto-wavelength and
auto-switching modes of your source, if the model allows it.
Note: Not all power meters have auto-wavelength and auto-switching detection
capacities. If the auto mode is not available, you cannot select it in the
Wavlength list. However, if the power meter has the capacity, but the auto
mode is still not available, a firmware update may be required. Please
contact EXFO to see how to proceed to update the firmware.
IMPORTANT
If you intend to take measurements with a very low power level
using the built-in power meter, make sure that your testing
conditions are optimal to ensure the best results (for example, do
not use the VFL).

Using the Optional Power Meters and VFL
Power Meter and VFL 11
Measuring Power or Insertion Loss
To perform power or insertion loss measurements manually:
1. If necessary, perform an offset nulling (see Nulling Offsets on page 4).
2. Check your fibers and clean them properly.
3. For insertion loss measurements, reference your power meter to a light
source (see Setting Reference Values on Your Power Meter on page 9),
then deactivate the light source.
4. If you have used a single reference patchcord, disconnect it from the
power meter port only, then attach a second reference patchcord to
the power meter.
OR
If you have used two reference patchcords, disconnect both of them at
the bulkhead.

Using the Optional Power Meters and VFL
12 Power Meter and VFL
Measuring Power or Insertion Loss
5. Using bulkhead adapters or the system patch panels, connect a fiber
under test to reference patchcord attached to the light source and
power meter.
6. From the Instrument View tab, use the list to select a wavelength.
Activate the source at the same wavelength.
7. Tap Add to transfer the displayed values to the Measurements list.
Note: If you tap Add just after switching to another measurement unit, the
application will prompt you to save any unsaved measurements. You must
either save these measurements and close the file, or discard them
(see Clearing Measurements from the Display on page 19) before being
able to add values expressed in the new measurement unit.
8. Repeat the procedure for other wavelengths.
9. Once your work is complete, tap Save.
IMPORTANT
If you specify a name that already exists, the original file will be
overwritten and only the new file will be available.

Using the Optional Power Meters and VFL
Power Meter and VFL 13
Measuring Power or Insertion Loss
To perform power or insertion loss measurements using the auto
wavelength or auto switching modes of your source:
1. If necessary, perform an offset nulling (see Nulling Offsets on page 4).
2. Check your fibers and clean them properly.
3. For insertion loss measurements, reference your power meter to a light
source (see Setting Reference Values on Your Power Meter on page 9),
then deactivate the light source.
4. If you have used a single reference patchcord, disconnect it from the
power meter port only, then attach a second reference patchcord to
the power meter.
OR
If you have used two reference patchcords, disconnect both of them at
the bulkhead.
5. Using bulkhead adapters or the system patch panels, connect a fiber
under test to reference patchcord attached to the light source and
power meter.
IMPORTANT
In auto wavelength or switching mode, there is a small delay (about
2 seconds per wavelength) allowed for refreshing the values. When
switching from one fiber to another, wait for these few seconds to
make sure that the measurement you are reading is not a residual
measurement from the previous fiber.

Using the Optional Power Meters and VFL
14 Power Meter and VFL
Measuring Power or Insertion Loss
6. From the Instrument View tab, select Auto. Activate the source with
the auto-wavelength or auto-switching mode.
Readings with more than one wavelength appear on-screen at the
same time when the auto-switching feature is enabled on the source.
If the auto-wavelength or auto-switching mode are not activated for
your source, and that you try to use the auto feature of the power
meter, you will be notified clearly in red, and no reading is displayed.

Using the Optional Power Meters and VFL
Power Meter and VFL 15
Measuring Power or Insertion Loss
7. Tap Add to transfer the displayed values to the Measurements list. In
auto-switching mode, the measurements are added for all
wavelengths at once, using one line per wavelength.
Note: If you tap Add just after switching to another measurement unit, the
application will prompt you to save any unsaved measurements. You must
either save these measurements and close the file, or discard them
(see Clearing Measurements from the Display on page 19) before being
able to add values expressed in the new measurement unit.
8. Once your work is complete, tap Save.
IMPORTANT
If you specify a name that already exists, the original file will be
overwritten and only the new file will be available.

Using the Optional Power Meters and VFL
16 Power Meter and VFL
Measuring Power or Insertion Loss
To view and edit power or insertion loss measurements:
1. Select the Measurements tab. All your measurements are displayed in
the order they were performed.
2. Tap Rename to rename the fiber, tap Delete to remove the selected
value from the list, or Clear All to remove all measurements from the
list.
To change the fiber name (in the case of multiple
wavelengths, they are all changed at the same time)
Fiber name
To delete the selected row from the table (in
the case of multiple wavelengths, they are
all deleted at the same time)
Wavelength at which power or
insertion loss was measured
Insertion loss measurement (in dB) or power
measurement (in dBm)
Average power
or insertion loss
measured per
wavelength