1.3 Typical Applications
PM200 test kits can be used as diagnostic and measurement tools of optical
transmission systems and fiber optic links. These applications can be found in several
industries, including premise, LAN, CATV, and Telco.
Two types of measurements are possible with the PM200 optical power meter: optical
power and optical loss.
1.3.1 Optical Power Measurement - When displaying power in dBm mode, the
PM200 will measure the absolute amount of power being received in the 2.5mm
Universal detector port. Absolute power is shown in dBm (decibels referenced to a
milliwatt), meaning the power being received by the photodetector is compared to 1
milliwatt of optical energy. Optical power measurement is useful for checking the
output power and/or stability of an optical transmission system or stabilized fiber
optic light sources.
1.3.2 Optical Loss Measurement - When displaying power in dB mode, the PM200
can be used to measure the optical power through a fiber optic link relative to an
optical reference point. Setting a reference point is also known as “zeroing” the
meter with a light source. Optical loss measurements are useful for measuring the
attenuation, or loss, of a fiber link. The loss value can then be compared to a pre-
calculated link budget, which is used to determine if the fiber link will operate within
the parameters of the transmission equipment.
The formula for calculating loss in a fiber link is:
L = P - P a r
where
L
is the amount of optical loss in dB,
P
is the absolute power in dbm, and
P
is the reference power in
a r
dBm.
Optical loss measurements can also be used for fiber optic link certification. Link
certification is a process where optical loss measurements are compared to a link
budget calculated using fiber optic cabling standards.
Data stored in the PM200 can be downloaded into the Reporter certification report
software. Fiber optic links can be certified against one of several popular fiber optic
cabling standards or one of two user configurable standards. Many fiber optic
installation bids are requiring certification reports, which makes the PM200 an
invaluable tool for fiber optic professionals.
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PM200 V1.0 11/04
EXTECH [ EXTECH INSTRUMENTS CORPORATION. ]
