The photoelastic method and the speckle technique are sued for measuring the stress and displacement field respectively.
The method uses laser speckle technique to record the shift amount of speckle patterns due to micro wedge angles, and thus micro wedge cangles of the test piece are induced.
The forming process and significance of laser speckle is analysed, it is reported that laser speckle techniques are applied to detect the impurity in infusion drugs.
