Synthetic Aperture Fourier Holographic Optical Microscopy

Optical+Biomedical Engineering Laboratory, School of Electrical, Electronic and Computer Engineering, The University of Western Australia, Crawley, WA, Australia.
Physical Review Letters (Impact Factor: 7.51). 11/2006; 97(16):168102. DOI: 10.1103/PhysRevLett.97.168102
Source: PubMed


We report a new synthetic aperture optical microscopy in which high-resolution, wide-field amplitude and phase images are synthesized from a set of Fourier holograms. Each hologram records a region of the complex two-dimensional spatial frequency spectrum of an object, determined by the illumination field's spatial and spectral properties and the collection angle and solid angle. We demonstrate synthetic microscopic imaging in which spatial frequencies that are well outside the modulation transfer function of the collection optical system are recorded while maintaining the long working distance and wide field of view.

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Available from: Sergey Alexandrov,
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    • "For example, a tilt can be introduced in the object [7] [8] [9] or in the plane wave illumination [10] [11] [12]. In the case of plane wave illumination, the object function is multiplied by a phase ramp, which slope is given by the director cosine of the illumination. "
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    ABSTRACT: We have developed a tomographic diffractive microscope in reflection, which permits to observe sample surfaces with an improved lateral resolution, compared to a conventional holographic microscope. From the same set of data, high precision measurements can be performed on the shape of the reflective surface, by reconstructing the phase of the diffracted field. Doing so allows for many advantages compared to classical holographic interferometric measurements: improvement in lateral resolution, easier phase unwrapping, reduction of the coherent noise, combined with the high longitudinal precision provided by interferometric phase measurements. We demonstrate these capabilities by imaging various test samples.
    Applied Optics 01/2014; · 1.78 Impact Factor
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    • "Massig et al. increased the NA by recording nine holograms with a camera (CCD array) translated to different positions and by recombining them in a single synthetic digital hologram [17]. Alexandrov et al. were able to break the diffraction limit by rotating the sample and recording a digital hologram for each position in order to capture the diffraction field along different directions [18]. A different approach was proposed by Kuznetsova et al. who rotated the sample in respect to the optical axis in order to re-direct the rays scattered at wider angles into the aperture of the optical system, thus going beyond its diffraction limit [19]. "
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    ABSTRACT: Resolution is an important issue in inspection of objects on microscopic scale. Various approaches have been investigated to increase the optical resolution behind the diffraction limit of an optical imaging system. However every time the optical resolution of a fixed optical system is overcome it is possible to speak of super-resolution. Demonstration that super-resolution have been deeply investigated in interference microscopy through various approaches. Here we discuss briefly the different techniques that have been adopted in interferometry and specifically in digital holography (DH). Then we illustrate a novel method that uses a dynamic diffraction phase-grating for increasing synthetically the aperture of a DH imaging system in lens-less configuration. Consequently the optical resolution of the DH systems can be increased of a factor of 3. The aim of the study is to demonstrate that super-resolution is possible and is a practical and viable method for a coherent optical microscope. We take benefit of the numerical reconstruction properties of DH in combination with diffraction grating to get super-resolution. The approaches could be used for metrology and imaging application in various fields of engineering and biology.
    Proceedings of SPIE - The International Society for Optical Engineering 06/2009; 7389. DOI:10.1117/12.830654 · 0.20 Impact Factor
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    • "The experimental setup described above is, in effect, probing the sample's spatial frequency spectrum, to the extent that it is represented by the Fourier plane optical field distribution, accurate in the absence of multiple scattering. An interesting alternative approach to wide-field microscopy is to map out this spatial frequency spectrum by adjustment of the illumination angle or wavelength [4]. Instead of recording a large range of spatial frequencies over a small field of view, as is conventionally the case, we record a small range of spatial frequencies over a large field of view. "
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    ABSTRACT: We describe the use of Fourier holography in wide-field characterisation and imaging of sample microstructure. In one approach, we spatially resolve the angular distribution of elastic scattering, but not the microstructure itself, and in another we perform a novel aperture synthesis to achieve high-resolution, wide-field imaging.
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