Optical power meters can measure the power of both single-mode and multimode fibers. In single-mode fiber, the rays travel down its entire length without any internal reflection at all. Optical power meters, also referred to as peak meters, are used in the installation, maintenance, and testing of fiber optic networks, whether single-mode. An optical power meter (OPM) is a type of electronic test device used to measure the power output of fiber optic equipment or the power or loss of an optical signal transmitted through a fiber cable. This. Fibre optic cable power meter and light source for multimode and singlemode cabling, LAN and telecom networks Instant results using the FiberMASTER Power Meter (PM) and Light Source (LS).