OPMs typically report the power either on a watts scale covering picowatts to milliwatts, or in decibel-milliwatts (dBm), which is the logarithmic ratio of the measured power to the reference value of one milliwatt. OPMs are often combined with other test instruments. For light power measurements outside the field of. The device then displays the power level in units of decibels (dBm) or watts (W) on a digital or analog scale. Optical Power Meters from the leading manufacturers are listed below. Use the filters to narrow down on products based on your requirement. This meter has standard features such as. Chat with a Specialist > Compare features, electrical/mechanical specifications, and form factor.