Search results for "DIGITAL HOLOGRAPHY"
showing 10 items of 59 documents
Single-exposure super-resolved interferometric microscopy by RGB multiplexing in lensless configuration
2016
Abstract Single-Exposure Super-Resolved Interferometric Microscopy (SESRIM) reports on a way to achieve one-dimensional (1-D) superresolved imaging in digital holographic microscopy (DHM) by a single illumination shot and digital recording. SESRIM provides color-coded angular multiplexing of the accessible sample׳s range of spatial frequencies and it allows their recording in a single CCD (color or monochrome) snapshot by adding 3 RGB coherent reference beams at the output plane. In this manuscript, we extend the applicability of SESRIM to the field of digital in-line holographic microscopy (DIHM), that is, working without lenses. As consequence of the in-line configuration, an additional r…
Cascaded adaptive-mask algorithm for twin-image removal and its application to digital holograms of ice crystals.
2009
An iterative Gerchberg-Saxton-type algorithm with a support constraint for twin-image removal from reconstructed Gabor inline holograms of single plane objects is described. It is applied to simulated holograms and to holograms of ice crystals recorded in the laboratory and in atmospheric clouds in situ. The algorithm is characterized by a distinction between object and background region and an iterative adaption of the object mask. Applying the algorithm to recorded inline holograms of atmospheric objects, the twin-image artifacts are removed successfully, for the first time allowing for a proper access to the in situ phase information on atmospheric ice crystals. It is also demonstrated t…
Lensless Object Scanning Holography
2012
Lensless object scanning holography (LOSH), a method for improving image quality in digital holography by combination of a set of digital holograms for different object positions is presented.
Wavefront holoscopy: application of digital in-line holography for the inspection of engraved marks in progressive addition lenses
2014
Progressive addition lenses (PALs) are engraved with permanent marks at standardized locations in order to guarantee correct centering and alignment throughout the manufacturing and mounting processes. Out of the production line, engraved marks provide useful information about the PAL as well as act as locator marks to re-ink again the removable marks. Even though those marks should be visible by simple visual inspection with the naked eye, engraving marks are often faint and weak, obscured by scratches, and partially occluded and difficult to recognize on tinted or antireflection-coated lenses. Here, we present an extremely simple optical device (named as wavefront holoscope) for visualiza…
Phase-shifting digital lensless Fourier holography for high numerical aperture in-line interferometric microscopy
2012
A new common-path and phase-shifting digital lensless Fourier architecture for high numerical aperture (NA) imaging in lensless in-line holographic microscopy based on the use of a spatial light modulator (SLM) is presented and experimentally validated.
Investigations of As-S-Se thin films for use as inorganic photoresist for digital image-matrix holography
2011
AbstractAs-S-Se chalcogenide thin films are successfully employed in classical and dot-matrix holography as inorganic photoresists for obtaining a relief-phase hologram. However using these films for image-matrix hologram recording has not been studied due to some features of image-matrix technology. For the applied research of the optical properties of As-S-Se films an experimental device of digital image-matrix holographic recording based on 100 mW 405 nm semi-conductor laser and Spatial Light Modulator (SLM) has been created. The device has the following main parameters: 140 × 105 µm frame size; laser intensity during exposure 10 W/cm2. With the help of this device diffraction grating an…
Femtosecond digital lensless holographic microscopy to image biological samples
2013
The use of femtosecond laser radiation in digital lensless holographic microscopy (DLHM) to image biological samples is presented. A mode-locked Ti:Sa laser that emits ultrashort pulses of 12 fs intensity FWHM, with 800 nm mean wavelength, at 75 MHz repetition rate is used as a light source. For comparison purposes, the light from a light-emitting diode is also used. A section of the head of a drosophila melanogaster fly is studied with both light sources. The experimental results show very different effects of the pinhole size on the spatial resolution with DLHM. Unaware phenomena on the field of the DLHM are analyzed.
Usage of moving nanoparticles for improved holographic recording
2013
Metal nanoparticles are used for different applications in holographic configurations. The metal nanoparticles are placed close to an object and encode it by a time varying random mask. A decoding mask is computed and used to obtain super-resolution digital hologram and eliminate the twin image and DC from a digital hologram. The method is also shown to be applicable for other optical methods.
Resolution enhancement and orders separation in on-axis nanoparticles based digital holography
2013
A method for eliminating the unwanted terms in an on axis hologram is presented. Free randomly distributed nanoparticles are used to encode and later on to decode/separate the desired term from the unwanted aberrations.
Off-axis digital holographic microscopy: practical design parameters for operating at diffraction limit.
2014
The utilization of microscope objectives (MOs) in digital holographic microscopy (DHM) has associated effects that are not present in conventional optical microscopy. The remaining phase curvature, which can ruin the quantitative phase imaging, is the most evident and analyzed. As phase imaging is considered, this interest has made possible the development of different methods of overcoming its undesired consequences. Additionally to the effects in phase imaging, there exist a set of less obvious conditions that have to be accounted for as MOs are utilized in DHM to achieve diffraction-limit operation. These conditions have to be considered even in the case in which only amplitude or intens…