Study of speckle size of light scattered from cylindrical rough surfaces.

The autocorrelation function of the intensity scattered from cylindrical rough surfaces is analytically obtained with the Kirchhoff scalar diffraction theory. It is shown that, in contrast to the case in which planar rough surfaces scatter radiation, this function, related to the speckle size, depends on the statistical parameters that characterize the surface and on the scattering direction. This result suggests a new, to our knowledge, optical method that can be applied to the characterization of cylindrical rough surfaces, such as in on-line quality assessment, in manufacturing processes. The calculated theoretical expression was tested, showing good agreement with experiments.

Directional image processing using a pinhole camera with a rectangular aperture.

This paper describes a new method of directional image processing based on a pinhole camera with a rectangular aperture.

Incoherent 2-D spatial filtering of screened images.

Incoherent 2-D spatial filtering can be achieved by means of an astigmatic system. Double screened pictures can be easily descreened with this method. Theoretical analysis and experimental results are presented.

Visual speckle technique for alignment and centering of a translucent rough surface.

A simple visual method is described which is based on the direct analysis of speckle pattern movement. It permits aligning a transparent diffuser, placing its rotation axis on the mean plane of the rough surface and simultaneously determining the optical axis. As a consequence, the direction of the illuminating light beam can be determined.