This thesis describes the development of a shearography instrument for the quantitativemeasurement of surface strain on dynamic test objects. Shearography is a non-contact,full-field interferometric speckle technique used for the measurement of displacementgradient. It is often used in industry for qualitative inspection of industrial components.To fully characterize the surface strain, a total of six components of displacementgradient are required. These can be measured using shearography instrumentation withat least three measurement channels. Phase measurements from each measurementchannel are combined using a matrix transformation to produce the orthogonaldisplacement gradient measurements.The instrument presented in this thesis possesses four measurement channels consistingof four views of the object under investigation. Images from the four views aretransported to the shearing interferometer using coherent fibre-optic imaging bundles.The signals from the four views are then spatially multiplexed onto the four quadrants ofa CCD camera. The optical source is a frequency doubled, pulsed Nd:YAG laser whichis used to effectively ‘freeze’ the motion of the dynamic object for the duration of thelaser pulse.The optical phase difference between images recorded from two laser pulses isdetermined using the spatial carrier technique. This method involves introducing acarrier frequency into the recorded speckle pattern using a Mach-Zehnderinterferometer. A Fourier transform is used to access the phase dependent spectralfeatures, from which the phase distribution is calculated.The instrument is first validated through the measurement of two static test objects. Theresults of these measurements are compared with modelled data and with results from amultiple-illumination-direction shearography system using a continuous-wave laser. Theinstrument is then used to investigate two dynamic objects; a plate rotating at 610 rpmand a speaker cone vibrating at frequencies in the range of 1 – 5 kHz.
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