An advanced digital speckle correlation method for strain measurement and nondestructive testing

An advanced digital speckle correlation method (DSCM) is presented in this paper. The advantages of this method will not only improve the processing speed but also increase the measuring accuracy. Some mathematics tools are derived and a powerful computing program is developed for further applications. A new feature of the measuring sensitivity of DSCM that can be varied by different amplification of the optical arrangement is first presented. This advantage may be superior to those available in other optical metrology methods like Electronic Speckle Pattern Interferometry (ESPI) in micro-deformation measurements. The applications of strain measurement and nondestructive testing are described and the advantages of DSCM are obvious. Some examples of material behavior measurement and plastic strain measurement are presented. Due to the high sensitivity of DSCM, another potential application in nondestructive testing (NDT) is also described in this paper. From the application examples given, this advanced DSCM proves to be a new and effective optical strain sensing technique especially for small objects or micro-deformation measurements.