The generation of a two-dimensional linear vector space in a coherent optical data processing system and its specific application to the gradient operator is discussed using theoretical and experimental results. The v...
详细信息
The generation of a two-dimensional linear vector space in a coherent optical data processing system and its specific application to the gradient operator is discussed using theoretical and experimental results. The vector space is created by superposing the outputs of two Fourier optical systems having light of mutually orthogonal polarizations. As a result, the total amplitude of the signal in the output plane is a vector sum of the signals from the systems. If each one of the systems performs one of the partial derivative operations of the transverse gradient, and if the inputs to both systems are identical, then the output is the vector sum of the partial derivatives or the transverse gradient operation. The experimental program is heavily oriented toward the realization of the optimum approximation to the j ω x î and j ω y j ˆ filters, rather than using various binary-type filters. Problems with film and lens noise are also discussed.
The setup used in many optical data processing schemes is a coherent optical image forming system. The most important element in this setup is the complex spatial filter. It can perform a large variety of linear opera...
详细信息
The setup used in many optical data processing schemes is a coherent optical image forming system. The most important element in this setup is the complex spatial filter. It can perform a large variety of linear operations upon the object or input. In general, it is difficult to produce complex filters, since both amplitude transmission and phase delay may vary across the filter plane in a complicated manner. Our own filters which are very similar to binary holograms, consist of many little transparent rectangles on opaque background. They can easily be drawn on a large scale by a computer-guided plotter, and then photographically reduced in size. We show that our filters, despite containing only amplitude values zero and one, can perform any dataprocessing operation which could be performed by any complex filter. After explaining the principle, we present three groups of applications. First, we describe new versions of some classical methods: schlieren observation and phase contrast. Next, we report on spatial filters which perform differential operations upon the object in order to enhance gradients or corners. Finally, we use our binary filters for signal detection.
The class of operations achieved by conventional coherent and incoherent optical data processing systems has been somewhat limited. Recent attempts to extend coherent optical processors to space-variant and non-linear...
详细信息
The class of operations achieved by conventional coherent and incoherent optical data processing systems has been somewhat limited. Recent attempts to extend coherent optical processors to space-variant and non-linear operations are reviewed. In addition, some new thoughts on the possible achievement of complex-valued operations using incoherent light are presented.
Photographic film is studied quantitatively as the input mechanism for coherent opticaldata recording and processing systems. The two important film characteristics are the amplitude transmission vs exposure (T A? E)...
详细信息
Photographic film is studied quantitatively as the input mechanism for coherent opticaldata recording and processing systems. The two important film characteristics are the amplitude transmission vs exposure (T A? E) curve and the film noise power spectral density. Both functions are measured as a function of the type of film, the type of developer, developer time and temperature, and the exposing and readout light wavelengths. A detailed analysis of a coherent optical spatial frequency analyzer reveals that the optimum do bias point for 649-F film is an amplitude transmission of about 70%. This operating point yields minimum harmonic and intermodulation distortion, whereas the 50% amplitude transmission bias point recommended by holographers yields maximum diffraction efficiency. It is also shown that the effective ac gain or contrast of the film is nearly independent of the development conditions for a given film. Finally, the linear dynamic range of one particular coherent optical spatial frequency analyzer is shown to be about 40–50 dB.
Routine passive techniques such as temperature and air current control are frequently not adequate to provide interference fringe stabilization in holographic optical data processing experiments. A successful active p...
详细信息
Routine passive techniques such as temperature and air current control are frequently not adequate to provide interference fringe stabilization in holographic optical data processing experiments. A successful active phase stabilization system that can be adapted to a variety of experimental configurations is described. It utilizes a synchronous lock-in amplifier and an electrooptic phase modulator to provide real-time stabilization of the interference fringe pattern. Both a video detection method and a direct optical detection method are experimentally evaluated in conjunction with the phase stabilization system.
In this paper, the use of transforms in optical data processing other than the Fourier transform, is suggested. Specific attention is given to the Mellin transform. Two methods of implementing this transform optically...
详细信息
In this paper, the use of transforms in optical data processing other than the Fourier transform, is suggested. Specific attention is given to the Mellin transform. Two methods of implementing this transform optically in real-time are suggested, initial demonstrations of an optical Mellin transform are provided, and various properties of the Mellin transform are discussed and its relevance to practical optical data processing (ODP) systems emphasized. Specifically, it is shown that the Mellin transform is scale invariant, can be implemented optically in real-time, a Fourier-mellin transform is scale and shift invariant, and the scale difference between two functions can be extracted by Mellin correlation.
The feasibility of using a Kerr magneto-optic-effect display as the input to a coherent optical computer is discussed and experimentally verified. Simple amplitude and phase distributions were generated on a continuou...
详细信息
The feasibility of using a Kerr magneto-optic-effect display as the input to a coherent optical computer is discussed and experimentally verified. Simple amplitude and phase distributions were generated on a continuous ferromagnetic thin film and their Fourier transforms were displayed with a lens. An experiment was performed demonstrating spatial filtering of a magneto-optically generated amplitude distribution. Magneto-optic generation of more complicated amplitude distributions requires a matrix-type thin-film structure and this input must be treated as sampled data.
This paper is an introduction to ideas and concepts that underlie coherent optical systems. It is pointed out that these systems are limited to spectral analysis and linear, space-invariant processing. However, progre...
详细信息
This paper is an introduction to ideas and concepts that underlie coherent optical systems. It is pointed out that these systems are limited to spectral analysis and linear, space-invariant processing. However, progress is now being made towards the realization of more flexible operations, including systems capable of nonlinear operations and space-variant linear operations. It appears likely that a number of coordinate-transformation-processing systems will be realizable in all-optical form in the future.
暂无评论