Abstract: An acoustic scanning apparatus is described having an acoustic grating for scattering waves into a focused beam. Surface acoustic waves are generated by a chirp signal generator and are introduced along one surface of the scanning apparatus. These waves propagate along the surface, are scattered by the acoustic grating and are thereby converted into bulk acoustic waves. The bulk acoustic waves converge into a focused beam inwardly directed at an angle to the surface acoustic waves. The focused beam scans at substantially the same speed as the surface acoustic waves traveling along the surface of the apparatus. The acoustic grating can also be used to convert bulk waves to surface acoustic waves as either a variable chirp rate generator or a variable pulse compression filter.

Abstract: Method and apparatus for making a hologram that controls both the amplitude and the phase of a reconstructing beam of light at each point on the surface of the hologram. The hologram is a transparency made from a conventional, color reversal photographic film that has multiple emulsion layers that are each selectively photosensitive to light of different wavelengths. The desired image to be produced from the hologram is initially processed into a matrix of Fourier transformed amplitude coefficients and a matrix of Fourier transformed phase coefficients. The hologram is made by first exposing the photographic film to an illumination pattern of the Fourier amplitude coefficients using light having a spectrum to which one of the emulsions is selectively photosensitive. The film is next exposed to an illumination pattern of the Fourier phase coefficients using light having a wavelength to which another emulsion of the film is selectively photosensitive.

Abstract: An acoustically scanned, optical imaging system for converting patterns of light into electrical signals. The system includes a monolithic convolver that scans incident light patterns using two counter propagating acoustic waves. Located in front of the convolver is an opaque grid that places a spatial periodicity into the light patterns. When the frequencies of the two acoustic waves propagating in the convolver are selected so that the difference between them is a function of the spatial periodicity placed in the light patterns, the minimum threshold signal or dark current from the convolver is substantially reduced. The imaging system also includes four alternative signal generating and processing circuits that can provide a one dimensional scan, a fast Fourier transform and a Fresnel transform of the light patterns incident on the convolver. Patterns of colored light also can be convolved into electrical signals by using colored filters as the grid.