The best method is to use a bare fiber adapter on the power meter to measure the output of the bare fiber, then attach the splice. No specific vendor is required for the Power Meter and Laser Light Source, but it must be able. The most accurate way of measuring the fiber attenuation coefficient requires transmitting light of a known wavelength through the fiber and measuring the changes over distance. These procedures, often develo obtain a meaningful value with any degree of precision. At values of a few tenths of dB/km, both resolution and accuracy should be at least a few hundredths of dB/km. 23%, this means. Fiber pigtails are simple in appearance, yet essential in function.