Power meters and sensors
are used to measure the output power of the incident light from both the light
source and the installed fibers.
The power meter normally
has built in calibration for the most frequently used wavelengths, but can be
calibrated for other wavelengths as well.
On older types of power
meters and sensors it may be necessary to recalculate the reading if output
power is measured at wavelengths other than 1310 mm.
Different types of sensor
(optical receiver) are available depending on the type of measurement to be
made and the wavelength range. The sensors normally used permit a measurement
range from + 10 to –80 dBm. Sensors are normally calibrated for 1310 and 1550
nm. If several power meters and sensors are used simultaneously, they must be
calibrated against each other in order to produce congruent results.
During routine maintenance
testing of telecom network installations and for testing relatively small
installations, such as data networks, a simple form of power meter should
suffice. These handheld instruments have a limited range and not the same
reliability as those described above.
Handheld power meters can
normally be connected for testing at different wavelengths: 850, 1310, and
15500.
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