[
    {
        "id": "authors:dexdx-n1e17",
        "collection": "authors",
        "collection_id": "dexdx-n1e17",
        "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20150127-080422520",
        "type": "article",
        "title": "Perturbation Treatment of High-Energy-Electron Diffraction from Imperfect Crystals",
        "author": [
            {
                "family_name": "Lewis",
                "given_name": "Alan L.",
                "clpid": "Lewis-A-L"
            },
            {
                "family_name": "Villagrana",
                "given_name": "Robert E.",
                "clpid": "Villagrana-R-E"
            }
        ],
        "abstract": "A modified-Bloch-wave expansion is used to develop a theory of high-energy-electron diffraction from imperfect crystals. To compute these new Bloch waves one must solve a linear hyperbolic system in n unknowns. Scattering among the Bloch waves is controlled by the matrix elements of the perturbing potential, and various approximations to this scattering are discussed. The hyperbolic system is transformed to normal form; in making this transformation, the unknown functions become the plane-wave amplitudes of the Darwin representation. The normal form reveals the region of determinacy of the system: a cone generated by the diffracted beams. The contraction of this cone to a line (the column approximation) is discussed in terms of the Bloch-wave scattering.",
        "doi": "10.1103/PhysRevB.6.4382",
        "issn": "1098-0121",
        "publisher": "American Physical Society",
        "publication": "Physical Review B",
        "publication_date": "1972-12",
        "series_number": "12",
        "volume": "6",
        "issue": "12",
        "pages": "4382-4392"
    },
    {
        "id": "authors:6m7tg-mf864",
        "collection": "authors",
        "collection_id": "6m7tg-mf864",
        "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20150311-081723790",
        "type": "monograph",
        "title": "Computer Enhancement of High Resolution Electron Micrographs Containing Weak Periodic Information",
        "author": [
            {
                "family_name": "Horgen",
                "given_name": "H. M.",
                "clpid": "Horgen-H-M"
            },
            {
                "family_name": "Villagrana",
                "given_name": "R. E.",
                "clpid": "Villagrana-R-E"
            },
            {
                "family_name": "Maher",
                "given_name": "D. M.",
                "clpid": "Maher-D-M"
            }
        ],
        "abstract": "Using image processing methods and Fourier synthesis techniques\nsimilar to those mentioned by Nathan (1970), it has been possible\nto enhance weak periodic information contained in electron micrographs\nobtained from what might be characterized as less than ideal\nthin films. This paper describes the results of such an experiment\nand illustrates the potential afforded by these computer techniques\nin an ultrastructural analysis of similar type objects.",
        "publisher": "Caltech Library",
        "publication_date": "1970"
    },
    {
        "id": "authors:fjk4q-mtj28",
        "collection": "authors",
        "collection_id": "fjk4q-mtj28",
        "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20150305-101206985",
        "type": "monograph",
        "title": "Computer Enhancement of Weak-Beam Images",
        "author": [
            {
                "family_name": "Horgen",
                "given_name": "H. M.",
                "clpid": "Horgen-H-M"
            },
            {
                "family_name": "Villagrana",
                "given_name": "R. E.",
                "clpid": "Villagrana-R-E"
            },
            {
                "family_name": "Maher",
                "given_name": "D. M.",
                "clpid": "Maher-D-M"
            }
        ],
        "abstract": "In order to perform quantitative image-contrast analysis of low-contrast\nelectron micrographs one must first increase the signal to noise ratio. As an example, consider the weak-beam method ' of\nimaging defects by transmission electron microscopy. In this technique\nan increase in the resolution of closely spaced dislocations is obtained\nthrough a narrowing of the individual dislocation image widths. However,\nthis reduction in image width is accompanied by a corresponding decrease\nin the signal to noise ratio, which in many instances renders quantitative\nimage-contrast analysis impractical. In this note we present an example\nof the computer image enhancement of a weak-beam micrograph.",
        "publisher": "Caltech Library",
        "publication_date": "1969"
    }
]