It is shown how spatial division multiplexing (SDM) offers a low-cost solution to polling large numbers of passive optical sensors in large sensor arrays and also provides the possibility of low-cost fiber optic sensor systems. The geometric versatility of SDM allows optical multiplexing to be at the source, in the fiber distribution system, or at the detector. In most cases, electronic scanning can be driven from low-cost microcomputers. The simplicity of SDM promises reliable and maintainance-free operation.