Sapphire optical fibre interferometric sensors

Yu, Zilan (2002) Sapphire optical fibre interferometric sensors. MSc(R) thesis, University of Glasgow.

Abstract

This thesis is mainly concerned with the development of single crystal fibre interferometric sensors. By studying the functional relationship between the angle of wedge-shaped air gap and the separation of consecutive fringes of equal thickness, results shows that the percentage difference of angles between the method of interference fringes and the direct calculated method is about 3.99%. Thus, a procedure of prototype was established to monitor the process of fabrication of a Fabry-Perot cavity. An intrinsic sapphire fibre-optic Fabry-Perot sensor was fabricated, and the functional relationship between the output of interference signal of the intrinsic sapphire fibre-optic Fabry-Perot sensor and temperature was deduced. The fitting equation, the functional relationship between temperature and the output of the number of interference fringes of the intrinsic sapphire fibre-optic Fabry-Perot sensor, was obtained by data fitting. There is a near linear relationship between the temperature measured and the output signal of the intrinsic sapphire fibre- optic Fabry-Perot sensor for the range of temperature 75 °C - 435 °C. An extrinsic sapphire fibre-optic Fabry-Perot sensor was fabricated, and the functional relationship between the output of interference signal of the extrinsic sapphire fibre-optic Fabry-Perot sensor and temperature was deduced. High temperature ceramic adhesive based on aluminum oxide was presented to solve the problem of unmatched thermal expansion between the support materials and the extrinsic sapphire fibre-optic Fabry-Perot sensor. Theoretical analysis showed that during the process of the fabrication of the interferometer cavity, the length of Fabry-Perot cavity for fabricating should be tightly controlled. Phase relationships between the output of the interference signal of a monolithic sapphire fibre-optic Fabry-Perot sensor and the angular frequency of sound wave was deduced. Some monolithic sapphire Fabry-Perot cavities were fabricated, and their internal surfaces were observed. The optical quality of the internal surface of the melted end of the sapphire Fabry-Perot cavities was assessed by Michelson interferometric testing. The experiments showed that interference fringes of equal inclination could be achieved if the internal surface of the monolithic sapphire Fabry-Perot cavities were approximately planar surface. Obviously, there is the potential to fabricate a monolithic sapphire fibre-optic Fabry-Perot sensor by the sapphire tube sheath method. Four problems are presented to discuss which should be solved in future in consideration to the structure and assembly of the monolithic sapphire fibre-optic Fabry-Perot sensor: This study in this thesis has elucidated the problems associated with procedures in fabrication, assembly, and test of sapphire fibre-optic Fabry-Perot sensor, and achieved greater insights into fabrication of the monolithic sapphire fibre-optic Fabry-Perot sensor which shows the market potential of such an approach in Aerospace and Automobile applications.

• Item Type: Thesis (MSc(R))
• Qualification Level: Masters
• Keywords: Optics.
• Colleges/Schools: College of Science and Engineering > School of Engineering
• Supervisor's Name: Sharp, Dr. James H.
• Date of Award: 2002
• Depositing User: Enlighten Team
• Unique ID: glathesis:2002-71271
• Copyright: Copyright of this thesis is held by the author.
• Date Deposited: 10 May 2019 10:49
• Last Modified: 04 Jun 2021 13:54
• URI: https://theses.gla.ac.uk/id/eprint/71271