Design and realization of active infrared imaging system based on power-over-fiber technique

We present an active infrared monitoring system based on the power-over-fiber technique. The system realizes the following main functions: the power supply via optical fibers, the laser lighting, the image acquisition and processing. In the demonstration system, the high-power laser light (at the wavelength of 808 nm) in the base station is transmitted to the remote unit via a 200-m long multi-mode fiber, whose core diameter is 200 mu m. The remote unit includes an optical beam splitter, a power manager module behind a photovoltaic power converter (PPC) to ensure a quasi-maximum power-supply, a camera, a microcontroller, and an optical transmitter. As the laser beam enters the remote unit, it is divided into three parts by an optical beam splitter. The first part is converted by the PPC to provide the required electrical power of the remote unit. Besides, to improve the power-supply ability of PPC, a maximum power point tracking technique is applied, and more than 77% of PPC's maximum output power can be obtained. The other two parts of the laser beam pass through respective beam-shaping lenses and are used directly for the infrared laser lighting. Therefore, the active infrared monitoring is achieved without extra laser lighting sources. The collected image data are transmitted via another single-mode fiber to the base station for further data processing. Experiment result shows an active and unnoticed image monitoring in the dark environment.