The objective of this work was to produce an instrument which could
undertake wholefield inspection and displacement measurement utilising a
non-contacting technology. The instrument has been designed to permit
operation by engineers not necessarily familiar with the underlying
technology and produce results in a meaningful form. Of the possible
techniques considered Holographic Interferometry was originally identified
as meeting these objectives. Experimental work undertaken 'provides' data
which confirms the potential of the technique for solving problems but
also highlights some difficulties.
In order to perform a complete three dimensional displacement analysis a
number of holographic views must be recorded. Considerable effort is
required to extract quantitative data from the holograms. Error analysis
of the experimental arrangement has highlighted a number of practical
restrictions which lead to data uncertainties. Qualitative analysis of
engineering components using Holographic Interferometry has been
successfully undertaken and results in useful analytical data which is
used in three different engineering design programmes. Unfortunately,
attempts to quantify the data to provide strain values relies upon double
differentiation of the fringe field, a process that is highly sensitive to
fringe position errors. In spite of this, these experiments provided the
confidence that optical interferometry is able to produce data of suitable
displacement sensitivity, with results acceptable to other engineers.....
