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. 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. It can provide detailed information. If the pigtail is sufficiently long, 10 meters or so, VIAVI SolutionsTM Optical Time Domain Reflectometers (OTDRs) with pulses as short as 1 foot can perform these measurements. Depending upon their particular specifications and the actual distances involved, some instruments may or may not use. Luminescence is measured by detecting the photons (light) a sample emits, converting them into an electrical signal, and expressing the result in relative light units (RLU).
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