How to choose an optical power meter and related
precautions
How to choose optical power meter
Optical instrument optical power meters are divided into different models,
precision, interface and other parameters. When using, choose the appropriate
optical power meter according to the different needs of users, and mainly refer
to:
1. Make
sure these models are consistent with your measurement range and display
resolution.
2. With
the dB function of direct insertion loss measurement.
3.
Choose the best probe type and interface type
4.
Evaluate the calibration accuracy and manufacturing calibration procedures to
match your optical fiber and connector requirements.
When
choosing meters, temperature is perhaps the most stringent criterion. On-site
portable equipment should be at -18°C (no humidity control) to 50°C (95%
humidity)
What
is Optical multimeter:
Used to measure the optical power loss of
the optical fiber link.
There are the following two optical
multimeters:
1. It consists of an independent
optical power meter and a stable light source.
2. Integrated test system
combining optical power meter and stable light source
In a short-distance local area network
(LAN), where the endpoints are within walking or talking, technicians can
successfully use an economical combination optical multimeter at either end, a
stable light source at one end and an optical power meter at the other end. For
long-distance network systems, technicians should equip a complete combination
or integrated optical multimeter at each end.
Precautions
Some manuals will only have two parameters: luminous power and transmission
distance. Sometimes it will explain the transmission distance calculated by the
fiber attenuation per kilometer, mostly 0.5db/km. Divide the minimum
transmission distance by 0.5, which is the maximum light that can be received.
Power, if the received optical power is higher than this value, the optical
transceiver may be burned out. Divide the maximum transmission distance by 0.5,
which is the sensitivity. If the received optical power is lower than this
value, the link may not work.
The unit of the optical power of the light source is dbm. It has its luminous
and received optical power in the manual of the fiber optic transceiver or
switch. Generally, the luminescence is less than 0dbm. The minimum optical
power that the receiving end can receive is called sensitivity, and the maximum
optical power that can be received is reduced. The unit of the desensitivity
value is db (dbm-dbm=db), which is called the dynamic range. The luminous power
minus the receiving sensitivity is the allowable fiber attenuation value. The
actual luminous power during the test minus the actual received optical power， the value
is the fiber attenuation (db). The best value of the optical power received by
the receiving end is the maximum optical power that can be received-(dynamic
range/2), but it is generally not so good. Because of the characteristics of
each optical transceiver and optical module, the dynamic range is different, so
the specific allowable attenuation of the fiber depends on the actual
situation. Generally speaking, the allowable attenuation is about 15-30db.
