Toward commercial realisation of whole field interferometric analysis

2013-06-24T13:13:58Z (GMT) by John R. Tyrer
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......