Laser speckle interferometry in stress analysis

• Main Author: Zhang, Jingbo
• Other Authors: Asundi, A.
• Format: Theses and Dissertations
• Published: 2008
• Subjects: DRNTU::Engineering::Manufacturing::Metrology
• Online Access: http://hdl.handle.net/10356/5831
• Institution: Nanyang Technological University

Laser speckle correlation interferometry enables the measurement of deformation/displacement components and can be used to extract quantitative information on strains/stresses by analysing the fringe patterns. Electronic speckle pattern interferometry (ESPI) or Digital Speckle Pattern Interferometry (DSPI) is a real-time measurement technique which has got wide range of applications in optical metrology in the measurement of deformation, displacement components and their derivatives, shape measurement and Non-Destructive Testing (NDT). It is based on the electronic detection using a Charge Coupled Device (CCD) camera combined with digital image processing of the speckle pattern. The speckled image data of the unloaded and loaded states of the object are processed and the results, in the form of fringe patterns, are displayed in real-time on a TV monitor. This thesis gives an account on the design and development of an orthogonal in-plane displacement sensitive configurations for the ESPI system. Applications of the system for strain analysis especially residual stress measurement using hole-drilling method are exemplified.