A typical fiber optic current sensor consists of the following components: Optical Fiber: The core component that transmits light through the fiber. Magnetic Field Sensing Element: This interacts with the magnetic field created by the electrical current. The FOCS can measure uni- or bi-directional DC currents up to 600 kA. The FOCS Series Fiber Optical Current Sensors are passive, all-dielectric devices designed for precise current measurement without metal components, making them immune to electromagnetic interference noise. They measure current using light that passes through a Faraday fiber and reflects back from. Jose Miguel Lopez-Higuera: Handbook of Optical Fiber Sensing Technology, John Wiley & Sons, 2002. P 603 Radiation absorption excites an orbital electron to a higher energy level. Radiation absorption creates electronic excited states that are trapped by localized defects for extended periods of. Accurate measurement of electrical current in devices is a fundamental technology that is essential for controlling and monitoring the systems and equipment that many industries and our daily lives depend upon.