The operation and benefits of an OLTS An Optical Loss Test Set is a mainstay for testing fiber optic cabling. The OLTS tests for the total amount of light loss on the fiber link. The test is performed with a light source which produces a continuous wave at specific wavelengths connected to one end of the fiber. A power meter with a photo detector is connected to the opposite end of the fiber link. The detector measures optical power at the same wavelengths produced by the light source. Working in concert, these devices determine the total amount of light lost. The measured loss is compared to a specified loss budget for the link to determine if it passes this “Basic” or “Tier 1” certification. Tier 1 certification is described in standards such as Telecommunications Industry Association’s (TIA’s) TSB140 bulletin entitled “Additional Guidelines for Field-Testing Length, Loss and Polarity of Optical Fiber Cabling Systems.” Tier 1 certification is required for virtually all fiber optic links today. A recent development in OLTS solutions is the availability of OLTS modules for copper cable analyzers. These modules can test two fibers at a time to verify polarity as well as test for loss in each direction.