Abstract: A linear optical processing system for copying graphic images which includes a spatial filter in the form of a Fourier transform hologram together with a lens for processing incoherent electromagnetic radiation. The system provides a given real, substantially-uniform low-pass two-dimensional optical transfer function for spatially filtering incoherent radiation within a range of spatial frequencies 0<.omega.<.OMEGA.. The spatial filter is made by forming a mask representing a point spread function which is the inverse transform of the desired optical transfer function, and employing the mask in a coherent system to produce as the filter a Fourier transform hologram of the mask.

Abstract: A linear optical processing system in which a spatial filter in the form of a Fourier transform hologram is included with a lens for processing incoherent electromagnetic radiation. Such a system provides a given real, two-dimensional transfer function for spatially filtering incoherent radiation within a range of spatial frequencies 0 .ltoreq..omega..ltoreq..OMEGA.. The filter is made by forming a mask of a graph of a point spread function which is the inverse transform of the desired transfer function, and employing the mask in a coherent system to produce a Fourier transform hologram of the mask. Spatial filters are designed for providing the resultant systems with various transfer functions, including (a) a directional response for passing substantially higher spatial frequency components in a first direction than are passed in a second direction; (b) a selective attenuator response; (c) a notch filter response; (d) a correctional filter response; and (e) a linear minimum mean square error response.

Abstract: A method of forming a minimum mean-square error linear filter photographically is disclosed.The optimum filter may be obtained photographically. In one form, a first photographic negative of a monolayer of cells having a high percentage of cells of the given type is made at the focal plane of a transforming lens mounted so as to collect the light scattered by the monolayer; and, developed for a gamma of unity. Thereafter, a second photographic negative is made at the same focal plane of a monolayer of cells containing a normal percentage of cells of the given type using the first negative as a filter. The second negative is developed for a gamma of two. The resulting photographic plate is a realization of the desired optimum (minimum mean-square error linear) filter.

Abstract: Cells of a given type spread among an ensemble of cells of various types are identified and, if desired, counted. Coherent light is directed toward a monolayer of cells of various types. The light scattered by the monolayer of cells is collected by a lens and the collected light is filtered by an optimum filter located in the focal plane of the lens. The optimum filter is a minimum mean-square error linear filter which suppresses light scattered by cells other than the given type of cell whereby the light scattered by the given type is enhanced. The intensity of the light passed by the optimum filter is related to the number of cells of the given type contained in the monolayer of cells. If desired, a second lens may be used to collect the filtered light and focus it toward an integrating and squaring detector.The optimum filter may be obtained photographically.