Devices such as Optical Power Meters, OTDRs, and Visual Fault Locators help technicians measure signal loss, locate faults, and verify fiber integrity. Understanding how these tools work enables faster troubleshooting and more efficient fiber network maintenance. Good OTDRs come with touchscreen interfaces, multiple wavelengths, and. The FiberLert™ Live Fiber Detector removes the guesswork, detecting invisible fiber optic light to check fiber activity, polarity, and connectivity. Optical Power Meter/Light Source A power meter and light source are both.