ABSTRACT
This chapter introduces optical metrology techniques. These are whole-field techniques and include: holography and hologram interferometry, speckle photography and speckle interferometry, moire interferometry, photoelasticity, and microscopy. All these techniques are extensively used in deformation studies, vibration analysis, and surface topography. The holography involves the recording of an interference pattern between an object wave and a reference wave. The record, after processing, is known as hologram. Speckle photography is used mostly to measure in-plane displacements and in-plane vibration amplitudes. In photoelasticity, models of objects are cast or fabricated from isotropic materials, which are then subjected to stress. The stresses produce physical deformations, which completely alter the initial isotropic character of the material. Some objects absorb light either completely or partially and hence can be easily seen in bright field microscopy. Others are naturally coloured or can be stained and hence are also seen in bright field microscopy.
