16
2-4-1 Normal Measurement Mode
Optical power can be measured using absolute or relative values.
You can set measurement conditions for each type of measurement.
■
Absolute Value and Relative Value Measurements
You can perform power measurement and loss measurement.
Power measurement involves measurement of absolute values.
The units of the measured values are either dBm or W (this
instrument uses mW, µW, or nW). With loss measurement, the
difference in optical power levels (dBm) from a reference value is
measured. Loss measurement involves measurement of relative
values. The units of the measured values are dB. The measured
value is displayed in the upper part of the screen (the largest
number).
<Display Example>
●
Absolute Value Measurement (Power
Measurement)
The display indicates that the measured
optical power level is -13.57 dBm. With
the power save function ON, light receiving
mode of CW light, and wavelength setting
of 1310 nm.
●
Relative Value Measurement (Loss
Measurement)
The display indicates that the measured
optical power level is -1.25 dBm relative to
the reference value (-13.57 dBm). If the
optical power level drops by 1.25 dB after
pressing the REF key, this indicates a 1.25
dB insertion loss in the section under test
(optical fiber, optical component, etc.).
■
Setting Measurement Conditions and Switching the Displayed
Units
●
You can enter settings for the measurement conditions of light
receiving mode, measurement wavelength, and averaging (see
section 3-3). You can set a reference value (REF) for relative
value measurement.
●
You can switch the units of display for the measured value to
either dB scale (dBm), or linear scale (W).
PWR SAVE
nm
CW
dBm
PWR SAVE
PWR SAVE
nm
CW
dBm
PWR SAVE
REF
nm
CW
dBm
dB
PWR SAVE
PWR SAVE
REF
REF
nm
CW
dBm
dB