Feasibility of a reflective pressure transducer

Most commercial pressure transducers make use of rather mature technologies for converting pressure into more easily manipulated electrical signals. The strain gauge and the capacitive transducer are but two of the more popular methods now in use. This study looks at the feasibility of designing a transducer which measures the amount of light reflected off a diaphragm. This design, termed optical reflective, involves fiber-optics to transmit and collect the light and uses a microprocessor to interpret the raw data.

This thesis considers the complete design of a pressure transducer using the optical reflective technique. Attention is focused in the components' governing equations, with the design emphasis on minimizing the transducer errors. An error analysis is included to indicate the cause and significance of the system uncertainties. Finally, comparisons are made with a large collection of commercial transducers.

With the optical reflective technique a pressure transducer can be designed that has increased accuracy, greater dynamic range, and better temperature stability than is available with today's commercial transducers. The accuracy of this design is better than 0.031% Full Scale, while the higher natural frequency (about double) 11 permits its use over a larger dynamic range. The tempera ture dependence is greatly reduced by having the optical circuit completely isolated from the pressure sensing element, thereby eliminating the need for thermal compensation of the electronic circuit. \