High-Temperature Displacement Sensor Using a White-Light Scanning Fiber Michelson Interferometer

As specialized materials are developed for various applications, it becomes desirable to test them under adverse conditions, such as at elevated temperatures and in harsh environments. It is increasingly important that sensors be developed to meet the growing needs of research and industry. The ability of sapphire to withstand elevated temperatures and many chemically harsh environments has long been recognized. However, currently available sapphire fiber possesses poor optical quality and is not available with a cladding. It has found use in a variety of temperature sensors, but the investigation of sapphire-based strain and displacement sensors has been limited. The primary development of a white-light Michelson interferometer that utilizes a sapphire fiber sensing head is presented in this thesis. Development includes efforts to combat the poor optical quality of the sapphire fiber, minimize polarization mode fading, and preferentially excite the fundamental mode of the sapphire fiber. This thesis demonstrates the feasibility of fabricating a Michelson white-light interferometer capable of measuring displacements in environments ranging from room temperature to 800 degrees Celsius. The sensor developed in this work is capable of measuring displacements exceeding 6.4 millimeters at room temperature, and exceeding 1 millimeter at 800 degrees Celsius. This thesis also presents the application of this sensor to the alignment of a sapphire-fiber based Fabry-Perot sensor. This technique allows the Fabry-Perot sensor to be aligned so that usable fringes are always obtained. Alignment of the sapphire-fiber based Fabry-Perot sensors has been considered prohibitively difficult.

Name thesis:degree_name

Master of Science

Level thesis:degree_level

masters

Discipline thesis:degree_discipline

Electrical and Computer Engineering

Department dc:contributor.department

Electrical and Computer Engineering

Grantor dc:publisher

Virginia Tech

Year dc:date.issued

1996

Author dc:creator

• Pedrazzani, Janet Renee

Chair dc:contributor.committeechair

• Murphy, Kent A.

Committee members dc:contributor.committeemember

• Wang, Anbo
• Claus, Richard O.

• sapphire fiber
• absolute displacement sensor
• Michelson white-light interferometery

Statement dc:rights

• In Copyright

Licence dc:rights.uri

• http://rightsstatements.org/vocab/InC/1.0/

Dc Identifier Other

etd-0104100-092104

OAI identifier oai:identifier

oai:vtechworks.lib.vt.edu:10919/30795