White light speckle method of experimental strain analysis

Speckle patterns used for displacement and strain analysis have previously been generated by laser light sources. The present paper introduces a method whereby the speckles are generated by white light in conjunction with the use of a retroreflective paint which has imbedded in it tiny spherical glass beads. The paint has the property of redirecting the light beam back to its original source. When recorded by double exposure the white light speckles behave exactly like laser speckles in that Young's fringes representing the displacement vector can be generated upon Fourier transformation of the resulting speckle interferogram. This property has been exploited in the development of a new two-dimensional strain analysis technique.