Pressure Sensing with Fiber Optics and Interferometry.
Abstract
A new pressure sensing device has been analyzed, built, and tested. The device uses a Michelson interferometer to monitor pressure-induced fluctuations of a polished silicon diaphragm. Probe flexibility is achieved by mounting the diaphragm on the end of a single mode optical fiber; the coupling apparatus used permits interference to occur with the fiber in one leg of the interferometer. The phase of the resulting pattern is locked using a piezoelectric length transducer and phaselock loop control techniques. Formulas developed to model the system input/output characteristics led to the construction of a working prototype. Long term drift for the system was negligible. Short term drift limited the resolution of the system to 7 mmHg over the region 50 mmHg to 200 mmHg. The limited range resulted from the scanning limit of the piezoelectric length transducer. System linearity was approximately 5 percent. Computer noise analysis identified the high voltage DC amplifier and the piezoelectric length transducer as limiting resolution to 3 mmHg. Acousto-optic modulation was examined as an alternative control method. This approach offers better resolution and better frequency response. The performance of the prototype pressure sensing system suggests that state-of-the-art specifications could be achieved by this method. Application for intravascular blood pressure measurement is discussed. (Author)
Document Details
- Document Type
- Technical Report
- Publication Date
- Dec 01, 1980
- Accession Number
- ADA100806
Entities
People
- Eddie J. Preston
Organizations
- Air Force Institute of Technology