JGR PDL 5, User Manual, Page: 11 / 83

PDL5 User Manual
PDL5-UM-00001 Rev 001 5
The internal switch and coupler of the PDL5 multimeter enable it to
automatically reference out the variations of the internal light source, the signal
offset with no light (dark current), and the total signal level from internal and
external backreflection (BRtot).
The backreflection in dB from a device under test (BR
DUT
) is calculated using the
following equation, where BR0 is the stored value of the total backreflection (in
dB) of the device under test (DUT):






  
10 10
0
10 10 log 10
BR BR
DUT
tot
BR
The PDL5 meter displays the value of BR
DUT
.
During power up, the meter will measure the dark current and the reference
power. Approximately every 90 seconds, the meter will automatically update
the reference power measurement, a process that only takes a fraction of a
second and does not cause any significant delays. In normal operation, the
PDL5 multimeter can take approximately 3 backreflection measurements per
second.
Loss and Power Measurement
The PDL5 multimeter is equipped with a front-panel InGaAs or Ge detector for
relative power (loss) and absolute power measurements. The meter is capable
of storing the dark signal from the detector so that high accuracy measurements
(as low as -80dBm for an InGaAs detector and -60 dBm for Ge detector) are
possible.
When making power measurements, the PDL5 multimeter will automatically
correct for dark current if the value has been stored. The power displayed (P) in
dBm is calculated from the total current measured when the light source to be
measured is illuminating the detector (Itot) and the value of the leakage or dark
current (Id) measured, using the following equation:
 
CAL I I P
d tot
   
log 10
Where “CAL” is the factory calibration value and is dependent on the
wavelength.
Output Port
The output ports of the PDL5 multimeter are equipped with an ultra-low
backreflection APC connector. To prevent damage to the output port
connectors, a measurement jumper (also called “launch cable”) must be used
for all measurements, even for measuring a component with an APC connector.