Showing papers by "Javier Garcia published in 2006"
TL;DR: An optical setup to achieve superresolution in microscopy using holographic recording is presented and optically implemented the approach for a low-numerical-aperture commercial microscope objective.
Abstract: An optical setup to achieve superresolution in microscopy using holographic recording is presented. The technique is based on off-axis illumination of the object and a simple optical image processing stage after the imaging system for the interferometric recording process. The superresolution effect can be obtained either in one step by combining a spatial multiplexing process and an incoherent addition of different holograms or it can be implemented sequentially. Each hologram holds the information of each different frequency bandpass of the object spectrum. We have optically implemented the approach for a low-numerical-aperture commercial microscope objective. The system is simple and robust because the holographic interferometric recording setup is done after the imaging lens.
243 citations
TL;DR: The method is defined in terms of an incoherent superposition of tilted wavefronts and has implementation advantages for applications in biological imaging or the microelectronic industry in which structured targets are being inspected.
Abstract: A technique based on superresolution by digital holographic microscopic imaging is presented. We used a two dimensional (2-D) vertical-cavity self-emitting laser (VCSEL) array as spherical-wave illumination sources. The method is defined in terms of an incoherent superposition of tilted wavefronts. The tilted spherical wave originating from the 2-D VCSEL elements illuminates the target in transmission mode to obtain a hologram in a Mach-Zehnder interferometer configuration. Superresolved images of the input object above the common lens diffraction limit are generated by sequential recording of the individual holograms and numerical reconstruction of the image with the extended spatial frequency range. We have experimentally tested the approach for a microscope objective with an exact 2-D reconstruction image of the input object. The proposed approach has implementation advantages for applications in biological imaging or the microelectronic industry in which structured targets are being inspected.
105 citations
TL;DR: A novel approach consisting of attaching a diffraction grating in parallel together with the object in the input plane and using off-axis illumination provided by a Vertical Cavity Surface Emitting Lasers (VCSEL) array to allow us achieving a major improvement in the optical resolution limit with an extremely low penalty in the complexity of the resulting system.
Abstract: We present a new approach to obtain superresolved images in digital holography by means of synthetic aperture generation using common-path interferometry and off-axis illumination in optical imaging systems. The paper includes two parts. First, we present a simple approach to double the resolution of an optical system using tilted illumination onto the object and an optical element in the image plane to produce the holographic recording. Then we present a novel approach consisting of attaching a diffraction grating in parallel together with the object in the input plane and using off-axis illumination provided by a Vertical Cavity Surface Emitting Lasers (VCSEL) array to allow us achieving a major improvement in the optical resolution limit with an extremely low penalty in the complexity of the resulting system. Experimental investigation based on commercial microscope objectives is presented.
96 citations
TL;DR: In this paper, a super-resolving approach based upon gray level coding of the information is described, which overcomes the resolution limitations caused either by the optics or by the finite size of the detector.
Abstract: In this paper we describe a super-resolving approach based upon gray level coding of the information. Thus, the imaged object should have limited number of gray levels. The proposed approach overcomes the resolution limitations caused either by the optics or by the finite size of the detector. In contrast to other existing super resolution techniques that use time or wavelength multiplexing, in this approach one does not need to pay neither in temporal nor in wavelength degrees of freedom, but in intensity dynamic range. After the gray coding and the imaging, the high frequency spatial resolution features are decoded using the decoding gray level lookup table.
35 citations
TL;DR: A superresolving approach that allows one to exceed the diffraction limit and recover highly resolved contours of moving targets from a sequence of low-resolution images is presented.
Abstract: We present a superresolving approach that allows one to exceed the diffraction limit and recover highly resolved contours of moving targets from a sequence of low-resolution images. The presented approach is suitable for remote sensing applications. The resolution decoding algorithm that is used to recover the high-resolution features of the target can be run partially via optical means and that way can be used to reduce the required computational complexity.
9 citations
TL;DR: The recognition method proposed is based on the calculation of the angle between the vector associated with a certain illuminated 3D object and that subspace and defines the angle in terms of linear correlations to get shift and illumination-invariant detection.
Abstract: A novel method of 3D object recognition independent of lighting conditions is presented. The recognition model is based on a vector space representation using an orthonormal basis generated by the Lambertian reflectance functions obtained with distant light sources. Changing the lighting conditions corresponds to multiplying the elementary images by a constant factor and because of that, all possible lighting views will be elements that belong to that vector space. The recognition method proposed is based on the calculation of the angle between the vector associated with a certain illuminated 3D object and that subspace. We define the angle in terms of linear correlations to get shift and illumination-invariant detection.
7 citations
TL;DR: A novel approach based on code division multiplexing technique is proposed in which the contrast of the identification peaks is significantly enhanced and the space-bandwidth product is improved.
Abstract: A joint transform correlator may suffer from overlapping of the zero diffraction order of the output, which does not contain relevant information, and the correlation peaks that appear in the first diffraction orders if objects are not sufficiently separated. Such overlapping significantly reduces the signal-to-noise ratio of the identification process. We propose a novel approach based on code division multiplexing technique in which the contrast of the identification peaks is significantly enhanced. The approach does not include placing the two objects side by side but rather includes code multiplexing them. Moreover, the code division multiplexing technique allows the space-bandwidth product to be improved. Optical implementation results are given.
6 citations
TL;DR: In this article, the experimental characterization of domain wall dynamics in a photorefractive resonator in a degenerate four-wave mixing configuration is presented, showing how the non-flat profile of the emitted field affects the velocity of domain walls as well as the variations of intensity and phase gradient during their motion.
Abstract: We report on the experimental characterization of domain wall dynamics in a photorefractive resonator in a degenerate four-wave mixing configuration We show how the non-flat profile of the emitted field affects the velocity of domain walls as well as the variations of intensity and phase gradient during their motion We find a clear correlation between these two last quantities that allows the experimental determination of the chirality that governs the domain walls’ dynamics
5 citations
Posted Content•
TL;DR: In this paper, the authors report the experimental characterization of domain walls dynamics in a photorefractive resonator in a degenerate four wave mixing configuration and find a clear correlation between these two last quantities that allows the experimental determination of the chirality that governs the domain wall dynamics.
Abstract: We report the experimental characterization of domain walls dynamics in a photorefractive resonator in a degenerate four wave mixing configuration. We show how the non flat profile of the emitted field affects the velocity of domain walls as well as the variations of intensity and phase gradient during their motion. We find a clear correlation between these two last quantities that allows the experimental determination of the chirality that governs the domain walls dynamics.
4 citations
Patent•
08 Dec 2006
TL;DR: In this article, an optical measurement system sensitive to light field amplitude is described, which uses an interferometer while a feedback loop maintains, at a low level, the light intensity exiting from at least on optical output of the interferometers.
Abstract: An optical measurement system sensitive to light field amplitude is disclosed. The system uses an interferometer while a feedback loop maintains, at a low level, the light intensity exiting from at least on optical output of the interferometer. Shot noise of a detector placed at the output of the interferometer is thus reduced, enabling high speed and high accuracy measurement without requiring is stronger light source. The measurement system may be used in optical computing.
3 citations
TL;DR: This paper proposes to interlace the different binary images into one single distribution and introduces the distribution in a conventional joint transform correlator, which gives the morphological correlation at a specific location.
16 Oct 2006
TL;DR: In this article, three methods for increasing the resolution of an aperture limited optical system by illuminating the input with structured light are discussed, ranging from tilted plane waves, coherence shaped light or speckle patterns.
Abstract: We propose and discuss three methods for increasing the resolution of an aperture limited optical system by illuminating the input with structured light The kind of illumination can be varied, ranging from tilted plane waves, coherence shaped light or speckle patterns In any case the high resolution of the projected pattern demodulates the high frequencies of the sample and permits its passage through the system aperture A decoding process provides the superresolved image after some digital post processing stage