Three simple systems of modulating the intensity of incoherent light in an optical transducer are described: (1) modulator using a variable-light attenuator; (2) moire fringe modulator; (3) a photoelastic modulator. The inputs to (1) and (2) are displacement, while that for (3) is force. The attenuations across the various transducers lie between 7 and 19 dB; optical fibre links of at least 100m are feasible.
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Department of Instrumentation and Analytical Science The University of Manchester Institute of Science and Technology PO Box No 88, Manchester M60 1QD, England;
