5-3
IM AQ7280-01EN
Optical Output and Optical Power Measurement
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Index
5.2 Measuring Optical Power (OPM, /PC option)
Measuring Optical Power Using the Optical Power Meter (OPM
Module)
Absolute power (dBm, W) and loss (dB) can be measured. You can set the measurement conditions
such as the wavelength and modulation.
Making Preparations for Measurements
Remove the optical fiber cables from the AQ7280 and close the optical connector covers, or make sure
that the optical power meter section is not receiving any light, and then start the optical power meter
zero-set procedure.
Performing Zero-Set
1.
From the top menu, select
Power Meter
to display the following screen.
Sets the reference to the currently
displayed measured value
Holds the measured value display
Measured value
Bar graph display of the
measured value
Set the wavelength.
See “Wavelength Mode” on page 5-4.
Set the modulation mode
(CW, 270Hz, 1kHz, 2kHz).
Set the unit (dB, dBm, W).
Performs zero set
Upper threshold line
Lower threshold line
Lines showing the upper
and lower threshold values
Set the reference (–80 to 40 dBm).
The Reference box appears if you
press the DREF soft key or set the
unit to dB.
Minimum
Maximum
2.
Execute
zero-set
.
Note
Perform a zero-set whenever necessary, such as after you have turned on the power or when the ambient
temperature changes. Performing a zero-set adjusts the internal deviation of the optical power measurement
section and enables you to obtain more accurate absolute optical power values.
Setting the Screen Display and Measurement Conditions
Unit
Set the optical power display unit from the following.
dB (absolute value), dBm (absolute value), W (absolute value)
• Unit W is preceded by a prefix m(10
‒3
), µ(10
‒6
), n(10
‒9
), or p(10
‒12
).
• The following relation holds between the absolute display unit dBm and W.
PdBm = 10×log(Pw×10
‒3
)
PdBm: Optical power (unit dBm), Pw: Optical power (unit W)
Reference
You can set a reference value and display the relative measured values (the differences from the
reference value).
• When you press the DREF soft key, the displayed measured value becomes the reference value.
From this point, relative values will be displayed. The unit changes to dB.
• When you press the DREF soft key or set the unit to dB, the Reference box appears on the
power meter screen.
• You can set the reference value in the Reference box. The range is –80 to 40 dBm.
• When you set the unit to dBm or W, the Reference box disappears, and the absolute measured
values will be displayed.
