Fiber optic power meters are instruments that measure the average power of a continuous light beam. They are used to test signal power in fiber optic networks. Other general purpose light power measuring devices are usually called radiometers, photometers, laser power. The PM60 and PM61 Series of Fiber Optic Power Meters are robust, full-featured, handheld instruments, which together cover the full range of optical fiber applications within the 400 - 1700 nm range with optical powers ranging from -70 dBm to +23 dBm (100 pW - 200 mW). It plays a critical role in testing and diagnosing optical networks, ensuring there are no signal strength problems and determining any difficulties.