In this paper, we present theoretical details and the underlying architecture of a hybrid optoelectronic correlator that correlates images using Spatial Light Modulators (SLM), detector arrays and Field Programmable Gate Array (FPGA). The proposed architecture bypasses the need for nonlinear materials such as photorefractive polymer films by using detectors instead, and the phase information is yet conserved by the interference of plane waves with the images. However, the output of such a Hybrid Opto-electronic Correlator (HOC) has four terms: two convolution signals and two cross-correlation signals. By implementing a phase stabilization and scanning circuit, the convolution terms can be eliminated, so that the behavior of an HOC becomes essentially identical to that of a conventional holographic correlator (CHC). To achieve the ultimate speed of such a correlator, we also propose an Integrated Graphic Processing Unit which would perform all the electrical processes in a parallel manner. The HOC architecture along with the phase stabilization technique would thus be as good as a CHC, capable of high speed image recognition in a translation invariant manner.
We describe a superparallel holographic optical correlator that performs two-dimensional spatial and angular multiplexing simultaneously. The key step in this architecture is the use of a holographic multiplexer to split a query image into many copies before it applies them to the holographic database. A holographic demultiplexer, in conjunction with an aperture, is used to identify the location and the angle of the brightest correlation peak. This architecture uses only O͑ p N͒ detector elements to search through N unsorted images in a single query. We demonstrate the basic features of this architecture, using three spatial locations with eight angle-multiplexed images in each location.
Measurements were made of the tensile strength of benzene, by the centrifuge method. The method is described, together with various features which have been incorporated into the procedure to insure uniformity of samples. There is evidence, which is not conclusive however, that the rupture strength increases as the amount of permanent gas dissolved in the liquid decreases. At any given permanent gas pressure in equilibrium with the liquid our results are highly variable. Although further confirmation is needed, it appears that the variability is a result of differing histories of our tubes and not of lack of uniformity of our benzene samples. Exposure of the glass surface to the atmosphere appears to decrease the tensile strength. Our highest observed rupture strength, 157 atmospheres, is believed to represent the adhesion strength of the benzene to the walls of a particular tube, and may be much less than the limiting tensile strength of benzene. No evidence for a temperature dependence of the tensile strength has been found, but this result is probably also not representative of the limiting tensile strength of benzene.
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