다중혈관 관상동맥 환자에서 y-문합을 이용하여 양쪽 내흉동맥만을 사용한 우회술의 조기 성적

[신간의 별자리x] 우리/미술, 그리고 ‘슬픔의 박물관’

A fast-Fourier-transform method of topography and interferometry is proposed. By computer processing of a noncontour type of fringe pattern, automatic discrimination is achieved between elevation and depression of the object or wave-front form, which has not been possible by the fringe-contour-generation techniques. The method has advantages over moire topography and conventional fringe-contour interferometry in both accuracy and sensitivity. Unlike fringe-scanning techniques, the method is easy to apply because it uses no moving components.

Fourier-transform method of fringe-pattern analysis for computer-based topography and interferometry

We review the recent developments in the area of optical fiber grating sensors, including quasi-distributed strain sensing using Bragg gratings, systems based on chirped gratings, intragrating sensing concepts, long period-based grating sensors, fiber grating laser-based systems, and interferometric sensor systems based on grating reflectors.

Fiber grating sensors

The PASCAL Visual Object Classes Challenge

Liquid lenses with adjustable focal length are of great interest in the field of microfluidic devices. They are, usually,
realized by electrowetting effect after electrodes patterning on a hydrofobic substrate. Applications are possible in many
fields ranging from commercial products such as digital cameras to biological cell sorting. We realized an open array of
liquid lenses with adjustable focal length without electrode patterning. We used a z-cut Lithium Niobate crystal (LN) as
substrate and few microliters of an oily substance to obtain the droplets array. The spontaneous polarization of LN
crystals is reversed by the electric field poling process, thus enabling the realization of periodically poled LN (PPLN)
crystals. The substrate consists of a two-dimensional square array of reversed domains with a period around 200 μm.
Each domain presents an hexagonal geometry due to the crystal structure. PPLN is first covered by a thin and
homogeneous layer of the above mentioned liquid and therefore its temperature is changed by means of a digitally
controlled hot plate. During heating and cooling process there is a rearrangement of the liquid layer until it reaches the
final topography. Lenses formation is due to the superficial tension changing at the liquid-solid interface by means of the
pyroelectric effect. Such effect allows to create a two-dimensional lens pattern of tunable focal length without electrodes.
The temporal evolution of both shape and focal length lenses are quantitatively measured by Digital Holographic
Microscopy. Array imaging properties and quantitative analysis of the lenses features and aberrations are presented.

Tunable liquid microlens array driven by pyroelectric effect: full interferometric characterization

Abstract. Polymeric thin films represent an emerging industrial area driven by their enormous technological and commercial potential in interdisciplinary sectors such as chemistry, material science, engineering, and physics. The large selection in terms of materials/composites and the wide range of technological solutions that could be used for their fabrication could create confusion for the final user requiring a quantitative characterization of their properties. This analysis could be even more complex in the case of functionalized polymeric films such as the samples reported in this work. Here we present how thin polymer films can be wholly characterized by applying a multiplicity of optical methods. Films were realized by a special liquid one-step process. Moreover, such polymer films were functionalized here for the first time by mesoporous silica nanoparticles. The nanoparticles were added to a polymeric matrix. We show that a full characterization was achieved by employing three different microscope techniques, i.e., scanning electron microscope, digital holography (DH), and space-time DH. Exploiting such a multimodal methodology can be of great benefit for characterizing the functionalized polymeric thin films. In fact, multiple characterization in different conditions was possible. The results reported in terms of morphological information, thickness distribution, three-dimensional (3D) mapping, large field of view, high magnification, and super resolution of the zoomed area offer a good solution for testing materials and obtaining a quantitative characterization and whole inspection in the case of complex polymeric samples.

Multimodal quantitative phase contrast characterization of thin polymeric film

Space-Time Digital Holography (STDH) exploits the object motion to record the hologram in a hybrid space-time domain. This representation adds new capabilities to conventional DH, such as unlimited extension of the Field of View (FoV) and tunable phase shifting. Here we show that STDH is able to improve the spatial resolution as well. Differently from other super-resolution approaches, stitching between holograms or their spectra is no longer required. Moreover, we introduce a new STDH modality to record and process hybrid space-time representations. This allows improving resolution with one single object scan, paving the way to the use of STDH for super resolution imaging onboard Lab on a Chip devices.

/pdf/2d-resolution-improvement-via-1d-scanning-space-time-digital-9s398hz4la.pdf

2D resolution improvement via 1D scanning Space-Time Digital Holography (STDH) in Optofluidics

In this chapter an approach using a 2D phase grating to enhance the resolution in digital holographic microscopy exploiting the electro-optic effect is proposed. We show that, by means of a tunable lithium niobate phase grating, it is possible to increase the numerical aperture of the imaging system, thus improving the spatial resolution of the images in two dimensions. The enhancement of the numerical aperture of the optical system is obtained by recording spatially multiplexed digital holograms. Furthermore, thanks to the flexibility of the numerical reconstruction process, it is possible to selectively use the diffraction orders carrying useful information for optimizing the diffraction efficiency and to increase the final spatial resolution.

Improving Numerical Aperture in DH Microscopy by 2D Diffraction Grating

We show how biological elements, like live bacteria species and Red Blood Cells (RBCs) can accomplish optical functionalities in DH systems. Turbid media allow coherent microscopy despite the strong light scattering these provoke, acting on light just as moving diffusers. Furthermore, a turbid medium can have positive effects on a coherent imaging system, providing resolution enhancement and mimicking the action of noise decorrelation devices, thus yielding an image quality significantly higher than the quality achievable through a transparent medium in similar recording conditions. Besides, suspended RBCs are demonstrated to behave as controllable liquid micro-lenses, opening new possibilities in biophotonics for endoscopy imaging purposes, as well as telemedicine for point-of-care diagnostics in developing countries and low-resource settings.

Pietro Ferraro

Papers

Tunable liquid microlens array driven by pyroelectric effect: full interferometric characterization

Multimodal quantitative phase contrast characterization of thin polymeric film

2D resolution improvement via 1D scanning Space-Time Digital Holography (STDH) in Optofluidics

Improving Numerical Aperture in DH Microscopy by 2D Diffraction Grating

Biological elements carry out optical tasks in coherent imaging systems