What is the power meter reading for weak light
A typical OPM is linear from about 0 dBm (1 milli Watt) to about -50 dBm (10 nano Watt), although the display range may be larger. Above 0 dBm is considered "high power", and specially adapted units may measure up to nearly + 30 dBm ( 1 Watt). Irrespective of power meter specifications, testing below about -50 dBm tends to be sensitive to stray ambient light leaking into fibers or connectors. Fiber Optic Measurement Units: "dB" and "dBm" Whenever tests are performed on fiber optic networks, the results are displayed on a power meter, OLTS or OTDR readout in units of "dB. Power (dBm) = 10 × log10 (Power in mW) A small change in dBm means a big change in mW.
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