They are designed to measure the power of optical signals, which is essential for ensuring the proper functioning of optical systems. In this article, we will explore the definition, history, and applications of OPMs, as well as their key features and specifications. In this article, learn: What is an optical power meter? An optical power meter (OPM) measures the power levels of light signals in devices that transmit data or power using. An optical power meter (OPM) is a device used to measure the power in an optical signal.