Search results for "holography"
showing 10 items of 210 documents
Using Partial Coherence and Digital Holography for 3D Imaging and Profile Extraction
2008
Two approaches for 3D imaging are presented. At first we use partial coherence of the light source and in the second we compute the unwrapped phase by illuminating the object from several slightly different angles.
Holographically aided iterative phase retrieval
2012
Fourier transform holography (FTH) is a noise-resistant imaging technique which allows for nanometer spatial resolution x-ray imaging, where the inclusion of a small reference scattering object provides the otherwise missing phase information. With FTH, one normally requires a considerable distance between the sample and the reference to ensure spatial separation of the reconstruction and its autocorrelation. We demonstrate however that this requirement can be omitted at the small cost of iteratively separating the reconstruction and autocorrelation. In doing so, the photon efficiency of FTH can be increased due to a smaller illumination area, and we show how the presence of the reference p…
Optically-undistorted digital holographic microscopy for quantitative phase-contrast imaging
2011
We propose a telecentric architecture for circumventing, by a pure-optical method, the residual phase distortion inherent to standard configuration of digital holographic microscopy (DHM). With this proposal there is no need for computer compensation of the parabolic phase during the phase map recovering procedure. Futhermore, in off-axis configuration, the spatial frequency useful domain is enlarged. The validity of the method is demonstrated by performing quantitative measurements of depth differences
Superresolved and field-of-view extended digital holography with particle encoding
2012
We present a new configuration for superresolution (SR) as well as for field-of-view (FOV) extension in a digital holography concept based on random movement of sparse metallic particles. In the SR configuration, the particles are in proximity to the recorded object, while in the FOV configuration, the particles are in proximity to the hologram plane. The particles' movement encodes the high spatial features in the plane of their movement. This high-resolution information can later be decoded by proper numerical postprocessing that either remedies the resolution limitations in the object plane (or the limited NA of the lens) or extends the FOV in the object plane.
Electron Holography for Electric and Magnetic Field Measurements and Its Application for Nanophysics
2011
Abstract Texture constitutes one of the fundamental properties of objects besides color and shape. In several image analysis applications, it is often the only exploitable quality of objects. As such, it has been studied, described, segmented, synthesized, or in short, analyzed extensively. Among the plethora of texture description methods, mathematical morphology deserves special attention as it excels at the exploitation of spatial relationships among pixels, rendering it inherently suitable for texture description. In this chapter, we focus on morphological texture description methods for grey-scale and color images in an effort to spread the advantages of this framework in the context o…
Enhancing spatial resolution in digital holographic microscopy by biprism structured illumination.
2014
A novel and efficient architecture of a structured-illumination digital holographic microscope (DHM) is presented. As the DHM operates at the diffraction limit, its spatial resolution on label-free imaging of transparent samples is improved by illuminating the sample with a structured illumination produced by a Fresnel's biprism. The theoretical analysis of the method forecasts a twofold improvement of the spatial resolution. The proposed method requires only two images to improve the spatial resolution, which eases the process of unmixing the high-resolution components by means of an unknown phase-shift procedure. Numerical modeling and experimental results validate the theoretical finding…
Compact and Field Portable Biophotonic Sensors for Automated Cell Identification (Plenary Address)
2021
In this Plenary address paper, we overview recently published work for automated cell identification using 3D optical imaging in compact and field portable biophotonic sensors. Digital holographic microscopy systems and lensless pseudorandom phase encoding systems capture 3D information of biological cells and make highly accurate automated cell identification possible. Overviewed systems include sickle cell disease diagnosis based on spatio-temporal cell dynamics in a field-portable 3D-printed shearing digital holography as well as lensless cell identification of both single and multicell samples using pseudorandom phase encoding.
Compressive imaging in scattering media.
2015
One challenge that has long held the attention of scientists is that of clearly seeing objects hidden by turbid media, as smoke, fog or biological tissue, which has major implications in fields such as remote sensing or early diagnosis of diseases. Here, we combine structured incoherent illumination and bucket detection for imaging an absorbing object completely embedded in a scattering medium. A sequence of low-intensity microstructured light patterns is launched onto the object, whose image is accurately reconstructed through the light fluctuations measured by a single-pixel detector. Our technique is noninvasive, does not require coherent sources, raster scanning nor time-gated detection…
Optical tweezing using tunable optical lattices along a few-mode silicon waveguide
2018
International audience; Fourteen years ago, optical lattices and holographic tweezers were considered as a revolution, allowing for trapping andmanipulating multiple particles at the same time using laser light. Since then, near-field optical forces have arousedtremendous interest as they enable efficient trapping of a wide range of objects, from living cells to atoms, in integrateddevices. Yet, handling at will multiple objects using a guided light beam remains a challenging task for current on-chipoptical trapping techniques. We demonstrate here on-chip optical trapping of dielectric microbeads and bacteria usingone-dimensional optical lattices created by near-field mode beating along a f…
Multiple Matched Spatial Filter Performed With Nonsymmetrical Fourier Transformers
1987
MULTIPLE MATCHED SPATIAL FILTER PERFORMED WITH NONSYMMETRICAL FOURIER TRANSFORMERSCARLOS FERREIRA and CARMEN VAZQUEZDepartamento de Optica. Universitat de Valencia.C/ Dr. Moliner, 50. 46100 Burjassot, Spain.1. INTRODUCTIONClassical matched spatial filters (CMSF) have been successfully employed for optical pattern recog-nition. To detect different signals, multiple matched spatial filters can be synthesized and several me-thods to perform the filters have been developed. Based on the sensitivity to input orientation of CMSF,we proposed a filter [1] where the signals to be detected were rotated by different angles when recordingthe hologram. Thus, the recognition of a signal is only achieved …