Soil vibration sensor employing optical fiber

• Grant number: 17/15787-7
• Support Opportunities: Research Grants - Innovative Research in Small Business - PIPE
• Start date: July 01, 2018
• End date: May 31, 2019
• Field of knowledge: Interdisciplinary Subjects
• Principal Investigator: Francisco Martim Smolka
• Grantee: Francisco Martim Smolka
• Company: Optolink Indústria e Comércio Sociedade Ltda
• CNAE: Fabricação de equipamentos e instrumentos ópticos, fotográficos e cinematográficos ; Pesquisa e desenvolvimento experimental em ciências físicas e naturais

Abstract

This Project is about the development of an optical fiber vibration sensor for physical structure monitoring as well as for seismic applications (seismometer). Using a patent pending, highly sensitivity displacement sensor, formed with a two fiber bi conical fused structure, we propose the construction of a vibration sensor in a configuration similar to the one used in inertial mass seismometers. In this scheme, the movement of the inertial body changes the transmission of light in the fiber of the displacement sensor. Thus, a totally passive sensor configuration, in the monitored area, can be connected with an optical cable, up to tens of kilometers, to the monitoring center. In this wayit will not require any electrical power in the field. Changing the value of the inertial mass and the support spring characteristics, the shelf frequency of the system can be adjusted in a range, from a fraction up to hundreds of Hz. In this way, the amplitude response of the sensor can be an accelerometer or a vibrometer (seismometer), depending on the frequency to be detected. The objective of the Project is to build an equipment with small dimensions and for use in applications ranging from vibration monitoring in physical structures such as bridges, buildings, dams and seismic events. Due to its simplicity, the complete sensor can be fabricated in Brasil. A prototype was already mounted and tested and is the object of a patent request at the INPI. With Fapesp support, the objective is to build one or more equipment with a proper mechanical case for real use and to be tested in a vibration (shake) table as well as in a temperature chamber in a specialized laboratory. Another objective is to test new mechanical configurations in order to increase sensitivity, noise reduction and lower frequency response, so to be used in seismic detections. Having conditions, work also in a 2 or 3 axis detection equipment. (AU)