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Browsing by Author "Cao, D. Q."

Now showing 1 - 3 of 3
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    Basic Image-Processing Operations By Use Of Acousto-Optics
    Banerjee, P. P.; Cao, D. Q.; Poon, Ting-Chung (Optical Society of America, 1997)
    We describe some basic optical image-processing operations with acousto-optic (AO) Bragg diffraction. Instead of using frequency-plane filters, we place an AO cell behind the abject. We then realize experimentally one-dimensional edge enhancement, which utilizes a high-pass filtering effect in the undiffracted order from the AO cell. A numerical simulation compares well with the experimental results. With two AO cells oriented orthogonally to each other, a second-order mixed derivative operation, evident from the four-corner enhancement of a square, is also demonstrated. (C) 1997 Optical Society of America.
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    Image Edge Enhancement with Two Cascaded Acousto-Optic Cells with Contrapropagating Sound
    Cao, D. Q.; Banerjee, P. P.; Poon, Ting-Chung (Optical Society of America, 1998-02-01)
    Basic real-time programmable image-processing operations are accomplished by use of acousto-optic (AO) cells. Instead of frequency-plane filters, the AO cells are placed directly behind the object. The one-dimensional edge-enhancement results with one AO cell can be improved by use of two AO cells that are placed in tandem with contrapropagating sound. The dominant second-derivative operation obtained from the transfer function of the undiffracted order works like a one-dimensional Laplacian operator that enables improved edge enhancement. (C) 1998 Optical Society of America.
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    Notch Spatial Filtering with an Acousto-Optic Modulator
    Banerjee, P. P.; Cao, D. Q.; Poon, Ting-Chung (Optical Society of America, 1998)
    The role of acousto-optic (AO) modulators in programmable real-time image processing has recently been demonstrated. For fully investigating the image-processing capabilities of the AO modulator, general techniques to derive spatial transfer functions are needed for a variety of physical situations. We develop a technique to determine the spatial transfer functions numerically for various cases of beam incidence on an AO modulator. Normal incidence and incidence at twice the Bragg angle are investigated as examples for which double-sided and single-sided notch spatial filtering, respectively, are achieved. The observed spatial-filtering characteristics are reconciled with simple intuitive physical arguments. (C) 1998 Optical Society of America.