Showing papers by "Giuseppe Coppola published in 2006"

The effect of 6-dimethylaminopurine (6-DMAP) and cycloheximide (CHX) on the development and chromosomal complement of sheep parthenogenetic and nuclear transfer embryos.

Abstract: The effects of activation by 6-dimethylaminopurine (6-DMAP) and cycloheximide (CHX) on the development and chromosomal complement of sheep parthenogenetic and SCNT embryos were investigated. The results revealed that the blastocyst development of parthenogenetic embryos was significantly higher (P 0.05) between the two activation treatment groups for SCNT embryos. The 6-DMAP or CHX treatment did not result in any significant difference in the blastocyst total cell number in either parthenote or SCNT embryos. The chromosomal analysis revealed that all the parthenogenetic embryos (100.0%) derived from 6-DMAP treatment, were chromosomally abnormal whereas in CHX-treated embryos, it was significantly lowered (93.6%, P 0.05) among the 6-DMAP and CHX- treated embryo groups (60.0% vs. 56.2%, respectively). This study demonstrated that oocyte activation agents such as DMAP and CHX have differing effects on meiotic or mitotic nuclei. The study also highlighted the feasibility of using bovine X and Y chromosome specific painting probes in sheep embryos.

Tunable two-dimensional hexagonal phase array in domain-engineered Z-cut lithium niobate crystal.

Abstract: An optical phase array with tunable phase step is demonstrated. The phase array consists of a two-dimensional hexagonal lattice of inverted ferroelectric domains fabricated on a Z-cut lithium niobate substrate. The electro-optically tunable phase step is obtained by the application of an external electric field along the z axis of the crystal via transparent electrodes. Theoretical analysis and experimental results are presented, showing that a tunable and flexible adaptive optical illuminator device can be realized by combining the electro-optic tunability with the Talbot effect. Generation of a multiplicity of light patterns is shown.

Digital Holography: Recent Advancements and Prospective Improvements for Applications in Microscopy

Abstract: This chapter has reported a detailed description and discussion of the recent advances and improvements in the novel interferometric technique of Digital Holography. Numerous examples have been shown of applications in microscopy for inspection, characterization, and investigation of different materials and processes. It is believed that the progress achieved in the reconstruction methods will find useful applications in different areas of homeland security, and we hope they can provide inspiration for further investigations for conceptual developments of new methods and systems useful in this field.

Holographic method with numerical reconstruction for obtaining an image of a three-dimensional object in which even points out of the depth of field are in focus, and holographic apparatus using such a method

Abstract: The invention concerns a holographic method with numerical reconstruction for obtaining an image of a three-dimensional object, said method employing a digitalised hologram of an object, and comprising a step A. wherein, starting from the digitalised hologram, extracting a phase image of said object corresponding to a bidimensional matrix MD of distance values; a step B. wherein a monodimensional subassembly SD of the distance value assembly present in matrix MD of the method step A is selected, subassembly SD containing distance values dk; a step C. wherein for each distance value dk, extracting from matrix MD a iso-level assembly IQdk corresponding to a monodimensional assembly of bidimensional coordinates of said object,- a step D. wherein for each distance value dk, reconstructing, starting from the digitalised hologram, a bidimensional matrix IMdk of intensity values relevant to said object; a step E. wherein, from each bidimensional matrix IMdk a bidimensional matrix IFdk of intensity values is extracted corresponding to the bidimensional coordinates of the iso-level assembly IQdk; a step F. wherein, starting from intensity values IFdk from the bidimensional coordinates of the iso-level assembly IQdk and from the relevant distance values dk, reconstructing the three-dimensional intensity image of said object, and wherein the resolution of the bidimensional matrix IMdk for all values of k is identical to the resolution of matrix MD of distance values.

Cytogenetic characterization of alpaca (Lama pacos, fam. Camelidae) prometaphase chromosomes

Abstract: The present study provides specific cytogenetic information on prometaphase chromosomes of the alpaca ( Lama pacos , fam. Camelidae, 2n = 74) that forms a basis for future work on kar

Thermo-electro-optical analysis of an integrated waveguide-vanishing-based optical modulator

Abstract: Silicon is the most widely used material in the microelectronics industry and it is becoming more widespread in integrated optic and opto-electronic fields. We present the thermo-electro-optical analysis of an integrated waveguide-vanishing-based optical modulator based on the free carrier dispersion effect. This particular structure allows one to obtain a planar device, with an easier CMOS compatible microelectronic integration. The implantation processes have been carefully tuned in order to get higher doping uniformity and a sharp profile. The process-flow is defined using the 2D process simulation software ATHENA (SILVACO International). The 2D semiconductor device simulation package ATLAS (SILVACO International) has been employed to analyse the coupled electro-thermal behaviour of our modulator in static and dynamic conditions. The electrical section of the modulation acts as a lateral p–i–n diode. The resulting channel waveguide shows single mode operation and propagation losses of about 10 dB cm−1. The modulator optical behaviour is based on the vanishing of the lateral confinement in the rib region. Results show that an optical modulation depth close to 100% can be reached with a power expense of about 650 mW and an operation −3 dB bandwidth of about 25 MHz.

Characterization of microelectromechanical systems by digital holography method

Abstract: The principle of the digital holography (DH) technique and the potentialities of the method are considered. Experimental results obtained using the DH microscopy technique for characterizing microelectromechanical systems (MEMS) are presented and discussed.

Controlling Image Recostruction Process in Digital Holography

Abstract: The reconstruction of digital holograms is a full numeric process. Such peculiarity offers the possibility to control several parameters during the reconstruction process. In this chapter we will describe some recent advancements of Digital Holography and how it is possible to control the numerical reconstruction process by optimizing or regulating different parameters. By controlling the reconstruction process it is possible to overcome some problems arising during the optical tests of materials and devices or to improve the imaging capability of DH for example for color 3D imaging.

An interferometric demodulation method for visualizing and determining quasi-static strain by FBG sensors

Abstract: In this paper, we propose an interferometric approach for visualizing and measuring the quasi-static strain experienced by fibre Bragg grating sensors. The method makes use of a simple bi-polished silicon sample acting like an etalon tuneable filter. The Bragg wavelength shift can be evaluated by analysing the overall interferometric signal achieved by tuning the etalon tuneable filter angularly. A fast Fourier transform method is applied for phase retrieval. The choice of the silicon sample is determined by the low-cost and well-developed silicon technology and fabrication, the easy design and tuneability of the spectral response, and the possibility of integrating on the same sample also the circuitry for electronic control. The principle of operation of this method is described and results obtained by employing such a configuration are reported.

Digital holographic microscope for dynamic characterization of a micromechanical shunt switch

Abstract: From the DH analysis we have found an asymmetric behavior of the device, probably due to impurities presence in the air gap between the bride an substrate. These results show all potentialities of this non destructive inspection method, that it promise to have a very important role in the futures processes of dynamic MEMS characterization.

Photonics Devices Based on Hybrid Approach Combining Liquid Crystals and Sol-Gel Waveguides

Abstract: In this article, the analysis of both an integrated electro-optic switch and a continuously tunable filter based on a Bragg grating in planar waveguide with a liquid crystal overlayer is reported. The fast and bistable switching of smectic C* in the surface-stabilized liquid crystal structure has been utilized in order to investigate the possibility of realizing an integrated electro-optical switch, whereas the soft-mode of smectic A* liquid crystals, allowing a continuous modulation of extraordinary refractive index, have been utilized in order to design an integrated wavelength filter in the wavelength range of interest for optical communication. Moreover, the performance of an electro-optical router, working at the wavelength of 1.55 μm and based on the multimode interference effects together with the electro-optic effect of smectic A* liquid crystal, is theoretically and numerically discussed.

2D lithium niobate microstructures: fabrication, characterization, and applications

Abstract: This work concerns the fabrication, optical characterization and potential applications of two types of microstructures manufactured in congruent lithium niobate. The first type consists of a simple 2D hexagonal lattice of inverted ferroelectric domains fabricated by standard electric field poling at room temperature. The second structure is the chemically etched version of the first one. Long etching in hot HF acid results in differential etching of opposite ferroelectric domain faces. In this way obtain a 3D structure is obtained in which the hexagonal domain array becomes an array of truncated pyramids. Both these structures are characterized through a digital interferometric analysis. The samples are inserted in the arm of a Mach-Zenhder interferometer and the digital holograms acquired are used to numerically reconstruct both the amplitude and the phase of the wavefront transmitted by the sample. Finally, we report on the possible applications of the fabricated structures. The hexagonally poled structure can be used as a variable binary phase array. In fact both sides of the poled sample are covered with a thin conductive layer (ITO), which acts as transparent electrode. By applying an external electric field it is possible to change the difference between the two phase levels, via the linear electro-optic effect, and, consequently, the distribution of light intensity in the diffracted orders. On the other hand, the 3D structured etched sample can be used as an micrometer size integral imaging system.

3D Imaging With Large Focus Extension By A Coherent Optical Microscope

Abstract: In microscopy, high magnifications are achievable for investigating micro‐objects but the paradigm is that higher is the required magnification, lower is the depth of focus. For an object having a three‐dimensional (3D) complex shape only a portion of it appears in good focus to the observer who is essentially looking at a single image plane. Actually, two approaches exist to obtain an extended focused image (EFI), both having severe limitations since the first requires mechanical scanning while the other one requires specially designed optics. We demonstrate that an EFI of an object can be obtained through digital holography (DH) without any mechanical scanning or special optical components. The conceptual novelty of the proposed approach lies in the fact that it is possible to completely exploit the unique feature of DH in extracting all the information content stored in hologram, amplitude and phase, to extend the depth of focus.

Interferometric measurement of thickness of silicon nitride layer in bi-morph silicon MEMS

Abstract: In this paper is reported a method for measuring the thickness of a silicone nitride layers employed for fabricating silicon MEMS bi-morph structures. The method allows the precise evaluation of layer thickness by adopting Digital Holographic Microscope. The measurement is based on the fact that the silicon nitride layer is transparent to the visible light. The optical phase difference (OPD) between the light beam traveling through the layer and portion of the beam in air is measured exploiting an interferometric technique. The approach is very simple and can be utilized even for inspection of non-planar or stressed structures. Experimental values have been compared with ellipsometric measurements.

Improvement of the reconstruction algorithm for extended focus image of MEMS by digital holography

Abstract: Digital Holographic Microscopy (DHM) is an optical interferometric technique for not destructive testing of micro-electro-mechanical systems (MEMS). A characterization process based on a no-contact technique allows us to analyze deformations, warping, residual stress, cracks and more other defects of MEMS, without destroy them. The flexibility of this technique allows us to improve novel numerical reconstruction algorithm for the recovery of more information. The post processing of the acquired holograms allows to reduce noise, optical aberrations, defocusing. In particular, the hologram reconstruction process has been modified to obtain Extended Focus Images (EFI). In Digital holographic microscopy, the use of microscopy objectives with high magnifications, reduces the focus depth. This means that for extended object a single reconstructed image with all the details in focus is not possible to obtain. Using a multiple reconstruction process and opportune resizing algorithms a full focused reconstructed images of extended object has been obtained without any mechanical movement. In particular, the advantages of the EFI technique are unique for dynamical characterization by DHM of extended objects, where the techniques based on multiple acquisitions fail. The EFI technique has been applied to obtain a best focused reconstructed image and profile of some micromechanical systems. It is demonstrated that this new approach allows to improve the accuracy in the EFI image when compared to the previous experimental results. Focusing of zones at different quote has been obtained evidencing, shape, crack and deformation impossible to observe otherwise at the same time. Moreover, these technique of reconstruction and analysis can be advantageous in many other fields of application.

Thermo-Electrical Analysis of an Optoelectronic Modulator Integrated in a SOI Rib Waveguide Operating in the Gb/s Regime

Abstract: Silicon is the most diffused material for microelectronic industry and, in recent times, it is becoming more and more widespread in integrated optic and optoelectronic fields. We present the thermo-electro-optical analysis of an integrated waveguide-vanishing-based optical modulator based on free-carrier dispersion effect, realizable on standard SOI wafer. The optical behavior is based on the vanishing of the lateral confinement in the rib region, and consequent cut-off of the propagating mode. Results show that an optical modulation depth close to 100% can be reached with a bandwidth of about 154 MHz. Smart electrical driving, that is an injection overdrive of a few volts for a very short time, allows to reach total ON-OFF switching time of about 860 ps. For that bias scheme the fall transient is then limiting the whole dynamic and the resulting bit rate in a pure digital modulation scheme is about 1.2 Gb/s