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

We propose a new Iterative Fourier Transform Algorithm (IFTA) capable to suppress ghost traps and noise in
Holographic Optical Tweezers (HOT), maintaining a high diffraction efficiency in a computational time comparable
with the others iterative algorithms. The process consists in the planning of the suitable ideal target of optical tweezers as
input of classical IFTA and we show we are able to design up to 4 real traps, in the field of view imaged by the
microscope objective, using an IFTA built on fictitious phasors, located in strategic positions in the Fourier plane. The
effectiveness of the proposed algorithm is evaluated both for numerical and optical reconstructions and compared with
the other techniques known in literature.

A new iterative Fourier transform algorithm for optimal design in holographic optical tweezers

A novel approach is presented for fabricating single or arrays of complex high-aspect ratio unique 3D microstructures The applicability of specific structures as optical tweezers and as excitable quantum dot-embedded microresonators is presented

Fabrication of functionalized Optical microstructures by exploiting nanofluidic instablites

Measurement of the refractive index of liquids is of great importance in applications such as characterization and control of adulteration of liquid commonly used and in pollution monitoring We present and discuss a fringe projection technique for measuring the index of refraction of transparent liquid materials© (1999) COPYRIGHT SPIE--The International Society for Optical Engineering Downloading of the abstract is permitted for personal use only

Liquid refractometer based on fringe projection technique

Tomography is one of the most powerful imaging tools for analyzing biological samples, able to furnish complete mapping of the object in 3D. In particular, tomographic phase microscopy (TPM) exploits quantitative phase imaging (QPI) techniques to map the 3D refractive index (RI) of cells, by adopting laser beam deflection, direct mechanical rotation or holographic optical tweezers (HOTs) to probe the sample along a number of controlled directions. To date, all tomographic methods require a high-precision, opto-mechanical and/or opto-electronic device to acquire a set of many images by probing the sample along a large number of controlled directions. Here we report on a smart solution to obtain TPM of samples at lab-on-chip scale, by exploiting their tumbling inside microfluidic channels. This method, recently developed, presents the following advantages: (i) Permits to observe full 360° of rotating cells, this avoiding the limitation in the accuracy of tomograms; (ii) no mechanical contact neither holographic optical tweezers are needed to rotate the sample; (iii) it is suitable for application in flowing conditions with high-throughput performances. This would allow real microfluidic biomedical applications on a large scale. The results shown in a previous work for RBCs and diatoms are here extended to quasi-spherical cells, by exploiting a new algorithm for rolling angle recovery in TPM. In particular, we performed the 3D imaging of human breast adenocarcinoma MCF-7 cells, opening the way for the full characterization of circulating tumor cells (CTCs) in the new paradigm of liquid biopsy.

Label-free imaging of cancer cells by in-flow tomography

A new method for direct patterning of Poly(dimethylsiloxane) (PDMS) structures is presented. This technique will be named Light Induced Patterning (LIP) as it's induced by laser light through a functionalized substrate of Lithium Niobate (LN) crystal. The process is a full field technique that, conversely to the point wise ones, allows PDMS patterning with a single laser light exposure. PDMS is a polymeric matter largely used in the fields of micro/nano fluidics, lab-on-chip and micro/nanoelectromechanical (MEMS/NEMS) devices. Interest in its employment is due to some properties as the high moulding handiness, biocompatibility and transparency in visible light. PDMS prototyping is usually realized by soft-lithography, that is, fabrication and/or replication of predefined structures using stamps, molds, or photo-masks. Here, a different method for direct patterning of PDMS microstructures is developed by taking advantage of photorefractive effect in a functionalized substrate. In particular the substrate we investigate is iron doped LN crystal 1cm 5× 1cm in y and z axes while thickness (x-axis) is 500µm (dopant level 0.05% weight). When the crystal is exposed to spatially modulated laser light a space-charge field arise inside the crystal [1,2] and it generates an electric field gradients patterns on its surface. Crystal is covered by a thin liquid film of PDMS, the electric field generated on its surface, causes a reorganization of the PDMS matter due to dielectrophoretic forces [3]. The liquid PDMS follows the geometric pattern of laser light illumination pattern. As final step, an appropriate thermal treatment is applied to the crystal while the light source is generating the PDMS structure. Heating is responsible of the PDMS cross-linking that leads a stable and reliable PDMS microstructure. Argon laser emitting at 514nm is used and the light distribution on the crystal sample is obtained by means of an 100µm amplitude grating (AG), inserted in the setup as depicted in Fig.1(a). The AG was imaged by a lens (L) whose focal length is 25.4mm. On the LN sample, a replica of the AG spatial intensity distribution, is obtained. The final structure correspondent to the setup of Fig.1(a) is displayed in Fig.1(b) where linear PDMS grating with 100µm period is imaged by a bright field microscope (5× magnification). Two dimensional structures of PDMS are realized substituting the linear AG (Fig.1(a)) with different ones of desired geometry. An example of the allowed patterns is showed in Fig.1(c) where an optical microscope image of radial channels is presented.

Pietro Ferraro

Papers

A new iterative Fourier transform algorithm for optimal design in holographic optical tweezers

Fabrication of functionalized Optical microstructures by exploiting nanofluidic instablites

Liquid refractometer based on fringe projection technique

Label-free imaging of cancer cells by in-flow tomography

Self-induced patterning of PDMS microstructures by photorefractive effect on Lithium Niobate crystals