This manual covers FIS Power Meters with 0. These units feature efficient circuitry for prolonged battery life, easy-to-operate button controls . Walk into any fiber test gear catalog and you will see "LSPM kit" listed alongside power meters, light sources, and OTDRs. The acronym is fiber-industry shorthand for Light Source and Power Meter — a matched pair of instruments used together to certify that a fiber link meets its loss budget. Optical power meters are available as stand-alone bench or handheld instruments or combined with other test functions such as an Optical Light Source (OLS), Visual Fault Locator (VFL), or as a sub-system in a larger or modular instrument. Designed for installation, commissioning, and.