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. After all, lasers produce positive optical power, so how could a sensor display, for example, −5 W? With thermopile-based laser power sensors, the answer usually lies in the temperature gradient inside the. Few meters are displaying Negative values of Following parameters although Current and Voltage values are in positive. Meter Pics are also attached for reference. 1: Energy Delivered-Received 2: Power Phase-A 3: Power Phase-B 4: Total Power Kindly advice for the rectification of this issue. For. By Mark Slutzki / March 18, 2026 English A negative reading on a laser power meter can be confusing during laser measurements.
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