Q: Why does a laser power meter show continuously changing readings—either drifting upward or downward over time?
A: This phenomenon—readings continuously rising or falling as the laser exposure time increases—is usually caused by the power density exceeding the probe's damage threshold.
When the power density is too high, the probe's surface coating gradually degrades, causing the absorptivity to change. In some cases, the absorptivity decreases, resulting in lower readings; in others, the coating's thermal properties change, causing abnormally high readings.
