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A whole-field method of double-exposure speckle photography is employed to determine metal surface roughness by correlation between two speckle patterns. A movable rectangular aperture that is mounted before an image lens is shifted between the exposures, which results in a decrease in the contrast of the reconstructed Young's fringes with increasing roughness. The technique permits evaluation of the roughness of particular points on a surface as well as the average roughness of an entire surface. Four sets of random surfaces that were prepared by different machine-finishing processes and with roughnesses ranging from 0.6 to 13 [[micro]meter] have been tested. Different methods have been carried out to process the test data, and a practical method for the evaluation of surface roughness is proposed. Key words: Speckle photography, speckle correlation, surface roughness.

We present a modified method of shearography, known herein as multiple-image shearography, whereby the curvatures of an object can be measured directly from the resulting fringes. It employs an image-shearing camera that produces three sheared images simultaneously to interfere with each other in the image plane. When film is doubly exposed before and after an object is deformed, three sets of fringes are observed of which one set would depict the second-order derivatives of surface displacement. The theory of the multiple-image shearography technique and its application to curvature measurements in plate bending are presented. Key words: Multiple-image shearography, curvatures, second-order derivatives.

The high-pass Fourier filtering technique with an opaque stopper is commonly used for the reconstruction of shearograms. We believe that no analysis of this technique as applied to the shearogram reconstruction has been described. We present here a theoretical analysis of this reconstruction system taking into account the stopper that blocks the low-frequency region in the Fourier transform plane. The results show that the light-intensity distribution after reconstruction is different from that of the original shearogram. High fringe visibility is obtained with high-pass filtering.