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Thesis-1986-Godfrey.pdf (4.53 MB)

Optical detection system for ultrasonic surface displacements

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thesis
posted on 2018-01-09, 11:19 authored by Martin W. Godfrey
The work was carried out with the aim of developing an optical interferometric detection system. This was to be applied to the quantative measurement of low amplitude, high frequency surface displacements (<1nm at several MHz). Two forms of interferometric detector are investigated. The performance and limitations in particular measurement situations are assessed for both types of interferometer. The first type of detector investigated is a miniature stabilised interferometer. The design of a stabilisation system is given, along with ways in which it can be optimised for a particular environment. The second type of detector studied is a quadrature interferometer. Various methods of processing the two channels of information from this device are discussed. The design of a new method of processing the signals is given, and its performance determined. The interferometric sensor is combined with a waveform digitiser and microcomputer to form an integrated detection system. Analysis of the waveforms obtained is performed by a system of Pascal programs developed for this purpose. The detection system is applied to tasks such as the calibration of other forms of transducer and the characterisation of artificial sources of acoustic emission. The results of experimental studies are given and the applications of such a system discussed.

Funding

SERC and Rolls Royce Ltd. (CASE studentship).

History

School

  • Science

Department

  • Physics

Publisher

© M.W. Godfrey

Publisher statement

This work is made available according to the conditions of the Creative Commons Attribution-NonCommercial-NoDerivatives 2.5 Generic (CC BY-NC-ND 2.5) licence. Full details of this licence are available at: http://creativecommons.org/licenses/by-nc-nd/2.5/

Publication date

1986

Notes

A Doctoral Thesis. Submitted in partial fulfilment of the requirements for the award of Doctor of Philosophy at Loughborough University.

Language

  • en

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