Towards an Intrinsically safe, optically powered sensor system

Sensor systems in which both the communication and power to the electronic sub-systems at the sensor head are provided optically are very attractive from the point of view of electromagnetic isolation. Recent trends in micro-electronics are providing devices that will work at the maximum voltage permitted by European standards for intrinsic safety. The limitations of power available via optical transmission place a heavy constraint on the design of protocols to carry out two way communication. A key problem is also how to partition the intelligence at the two ends of the fibre link. Appropriate sub-systems have been designed, built and tested.