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A Fabry-Perot etalon placed in the object plane of a coherent optical processing system can be used as a variable bandpass preprocessing filter. Use of this filter leads to improved correlation signals in a matched spatial filter system. Experimental results are shown and compared with results obtained by two other preprocessing methods.

A new type of holographic optical element combines some of the flexibility of computer-generated holograms with the high light efficiency of volume phase holograms to produce optical elements capable of arbitrary illumination transformations with nearly 100% light efficiency. The optical element is recorded by subdividing a volume hologram film surface into numerous small areas (facets), each of which is individually exposed. A final optical system consisting of two dichromated gelatin holograms in series is demonstrated. The first hologram spatially redistributes the incident light, and the second hologram produces a desired phase front on the redistributed light.

A wavelength-coded source is used for spectral encoding of a spatial signal. The signal is passed through an aberrating medium and then a spectral decoding filter. A high signal-to-noise ratio image is present in real time at the system output.

We have shown experimentally that for high exposure, higher order Bragg diffraction by volume holograms is dominated by the nonlinear refractive index modulation and proposed the application of nonlinear modulation to the construction of a high frequency volume-grating waveguide coupler.

Wavelength-multiplexed matched spatial filters are used in an incoherent optical pattern recognition system. The system produces color-coded correlation responses which allow the simultaneous recognition of several objects and, in addition, reduces the requirements on filter positioning devices. Analysis of the system, comparison with previous systems, experimental results, and discussions are given.

A hybrid hologram is constructed which combines the flexibility of a computer-generated hologram (CGH) with the high-diffraction efficiency of volume phase holograms. The new hologram is constructed by using a spatially filtered wave front from a conventional 246- x 256-cell CGH as the object wave for the recording of a volume hologram. Theoretical and experimental results show that simultaneous high-diffraction efficiency and reconstruction fidelity are possible.

Optical Fourier processing is carried out by placing volume-hologram filters in the object plane of an optical system instead of in the conventional Fourier plane. This new type of Fourier processing is analyzed, and experimental results of optical differentiation by a volume-hologram filter are shown.

A new type of hologram that combines computer-generated holograms with volume holograms is described. This hologram allows arbitrary selection of the location and color of a computer-generated image when white light illumination is used. Potential applications include optical information processing, holographic optical elements, multicolor displays, and lens testing. Calculations are made to determine the range of wavelengths possible for image reconstruction. Experimental results are given and discussed.

A method of 2-D size-averaged incoherent recognition filtering is described. White light input illumination is used to multiplex chromatically a continuum of inputs differing in their spatial Fourier spectral magnifications. A two-grating dichromated-gelatin lateral-dispersion compensating device is inserted to correct chromatic dispersion introduced by a computer-generated hologram filter. The resulting registered recognition patterns are added to form a single effective filter size-averaged recognition peak. Using high efficiency compensating gratings and a bleached binary hologram allow the use of a relatively low-power light source.