Development of a design technique for optically powered class of electronic sensors.

摘要

In exploring a new application of optical fibers in the sensing area, the author has successfully developed a hybrid type optical fiber sensor system. This sensor system solely utilizes optical energy sent via an optical fiber transmission link to power the electronic sensor at the sensing end. This feature of the optically powered class of sensor will make it an increasingly attractive alternative for applications where semiconductor-based electronic sensors are preferred over other fiber optic sensor technologies. Areas of application include aerospace/aircraft instrumentation, process control industry, robotic, and medical test equipment.; Key results of this research are next identified. In the optical system both LED and LD types of sources are characterized. Limitations on LED systems are given. Different techniques of achieving better power coupling between LD and optical fiber are illustrated. Three important results are described in detail for the power converter unit. First, problems associated with conventional series-connected photovoltaic cells for non-uniform, low-level illumination applications are identified. An alternative, higher efficiency unit is illustrated. Key factors governing the overall unit efficiency are analyzed in detail. Associated second-order effects in this alternative unit are identified and their solution discussed.; In the micro-power remote electronic unit, a unique sensor signal encoding technique is developed. One technique, utilizing a single echo pulse to encode time delay is presented. An alternative technique, a double-pulse encoding scheme, is described in detail. Both advantages and limitations of these schemes are discussed. A novel and efficient LED-pulse transmitter with its supply voltage below the LED threshold voltage is described in detail. At the central processing module, a practical optical receiver design technique is illustrated. Various software data conversion methods and system commands implementation are detailed.; The design process is complex, and a systematic design procedure both at system integration and modular levels is presented. The design procedure described provides a basis for further development of this class of sensor systems. The ultimate goal is to have an integrated circuit chip which will be valuable to the system level designer. Applications of the successfully developed system prototype include sensing methods of resistance, voltage, and capacitance. (Abstract shortened with permission of author.)