Abstract
A new type of fiberoptic transducer is proposed as a means of detecting blood pressure by utilizing a single polarization fiber (SPF) and photoelastic materials. Pressure sensing is based on the photoelastic effect of the small size element. Linearly polarized light from He-Ne laser is transmitted through the SPF to the photoelastic element attached to the tip of SPF. Linearly polarized light incident into the photoelastic element is affected by stress applied uniaxially and the change of the state of polarization is detected with the analyzer. The photoelastic elements that are the most important components of this transducer have been studied with respect to a large number of materials. As a result, it has been found that GaP {111} and epoxy resin were most appropriate. A model experiment to comfirm the operation of the transducer has been carried out by arranging the light source, each of optical elements, SPF and the photoelastic elements. Moreover, the prototype pressure transducer intended for catheter-tip micromanometer has been assembled and tested for hydrostatic pressure. The pressure transducer proposed has been found to have satisfactory properties in sensitivity, linearity and frequency response. Therefore, it is possible to develop a catheter-tip manometer smaller than 2.2mm in diameter (7F) and also to design a multifunctional all-fiberoptic transducer.
