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Browsing by Author "Doh, K. B."

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    On the Theory of Optical Hilbert transform for incoherent objects
    Poon, Ting-Chung; Doh, K. B. (Optical Society of America, 2007-03-01)
    The Hilbert transform as been investigated abundantly in coherent imaging. To the best of our knowledge, it is for the first time investigated in the context of incoherent imaging. We present a two-pupil optical heterodyne scanning system and analyze mathematically the design of its two pupils such that the optical system can perform the Hilbert transform on incoherent objects. Computer simulations of the idea clarify the theoretical results. (c) 2007 Optical Society of America.
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    Optical image coding with a circular Dammann grating
    Doh, K. B.; Dobson, K.; Poon, Ting-Chung; Chung, P. S. (Optical Society of America, 2009-01-01)
    A circular Dammann grating in the front focal plane of a lens is used to generate an annular beam in the back focal plane to code an object by two-dimensional scanning. The coded image of the object is decoded digitally by convolving it with the same annular beam used to code the object. Simple inverse filtering is subsequently used to improve the contrast of the decoded image. (C) 2008 Optical Society of America