Optical processing by fringed speckles registered in a BSO crystal

Abstract

An alternative image multiplexing technique, employing a multiple-aperture pupil for each exposure, is presented. The aperture arrangement of the pupil is modified between exposures. A thick photorefractive BSO crystal is used as recording material. The technique allows concentrating the spectral components of a pair of images selectively into isolated spots in the Fourier plane. Two applications are proposed, in image processing and optical metrology.

Experimental study of volume speckle in four-wave mixing arrangement

“…In previous papers, the use of a thick photorefractive crystal as a speckle recording medium was proposed [13][14][15][16]. In [17][18][19], the storage in a sillenite crystal of low frequency modulated speckle patterns is analyzed. In this case, the image of a coherently illuminated diffuser is formed onto the crystal by an optical system whose pupil consists of two or more iden tical apertures.…”

“…In this case, the image of a coherently illuminated diffuser is formed onto the crystal by an optical system whose pupil consists of two or more iden tical apertures. In addition, it has been investigated that the features of a multiple exposure specklegram are obtained by using different multiple aperture arrangements for recording [19]. Standard couple wave theory proved to be an adequate theoretical frame to interpret the differ ent experiments mentioned above, which take ad vantage of the three-dimensional nature of the speckle patterns.…”