This 650nm optical power meter series is a compact and an easy-to-use testing instrument for optical fiber networks, which can be used for absolute optical power measurements as well as for relative loss measurements in optical fibers. The simple layout guaranties sh rt learning period. Use TOM101 in combination with TOM201 mini handheld light source. The 650nm wavelength is a cornerstone of visible red light applications in fiber optics, particularly for Plastic Optical Fiber (POF) and visual fault location. Understanding. Optical Power Meter, 650Nm Red Lighting, 7 Wavelength Optical Power Tester, Wide Range, High Accuracy Fiber Optic Cable Light Tester for Fault Detection (10MW) Found a lower price? Let us know.