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Networking Fundamentals · Intermediate

Optical Power Meter (OPM)

A tool that measures optical power in a fiber, used with a light source to measure end-to-end loss.

Definition

With a calibrated light source at one end and the meter at the other, technicians measure insertion loss and compare it with the loss budget. Readings are in dBm or dB.

Example

A light meter reads -17 dBm at the receiver, within the optic's sensitivity range.

Exam tip

An OPM plus light source performs Tier 1 loss certification; OTDR is Tier 2.

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