A feasibility and design study for an electro-optical pressure transducer

An investigation of the feasibility of using an electro-optical pressure transducer and optical membranes for measuring static surface pressures is reported here. The fundamental geometrical characteristics of a circular membrane under a uniform pressure load are examined, leading to the development of expressions for the maximum displacement, radius of curvature, and projected image radius as functions of pressure. An analysis of the basic stress and strain relationships, essential for the understanding of membrane tension, is included. Also presented is the relationship derived for the pressure differential, implicitly dependent on membrane tension, which allows pressure determination by the measurement of either the image radius, area, or light intensity. An automated data acquisition system is described which was used to verify experimentally the theoretical behavior of the membrane transducers. Experimental results obtained with the automated system are shown to be in good agreement with conventional transducer measurements. Finally, some potential limitations on the application of membrane transducers to wind tunnel environments are briefly discussed.