When there's loss in a fiber optic system, the measured power is less than the reference power, resulting in a negative logarithmic value and a negative dB reading on the meter. In other words, the laser is usually not the problem; the measurement conditions are. Other general purpose light power measuring devices are usually called radiometers, photometers, laser power. An optical power meteris a dedicated instrument for measuring the precise strength of light in optics. All of our surgical devices and whether they are working correctly and producing the appropriate amount. EXFO can help save both time and costs with an automated calibration test system that is designed for the verification of power meters, attenuators, sources and optical time-domain reflectometers (OTDRs). Despite the meter displaying a negative number, convention dictates referring to the loss as a positive value. Here is an Excel spreadsheet that calculates dB/power ratio and dBm/milliwatts.
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