Tiny Aperture Research Articles

Pre-Clinical Evaluation of Left Atrial Appendage Closure Device in Mitigating Risk of Stroke in Patients with Atrial Fibrillation: Promising Results from Animal Trials with Future Prospects

Abstract: Atrial fibrillation (AF) is the most common clinical disorder of cardiac arrhythmia in geriatrics, characterized by the presence of disorganized and irregular electrical activity in atrial myocardium, which leads to worsening of the heart's systolic function. Left atrial appendage (LAA) is a tubular, tiny aperture construction, connecting the left atrium (LA) with separate structure from LA with distinctive mechanical, hormonal, and structural properties. AF and Mitral valve regurgitation disease elevate the chances of thrombus formation in LAA, these ultimately turns into stroke. Obstructing thrombus by using a Left Atrial Appendage Closure Device (LAAC) and preventing it from entering internal carotid arteries, the risk of LAA thrombosis can be decreased. This article serves as a comprehensive compilation detailing the successful development and implantation of Left Atrial Appendage Closure (LAAC) Device with its novel design and geometry in two pigs (pre-clinical evaluation), showcasing promising results that have future implications for addressing cardiovascular disease in humans.

High-performance digital shearography integrating spatial light modulator with micro-polarizer camera

Digital shearography (DS), a laser-based optical interferometric method, is widely employed for measuring the first-order derivative of an object's surface deformation. Unlike digital holography, DS integrates self-reference optics, enhancing resistance to environmental disturbance and improving detection sensitivity, making it ideal for non-destructive testing (NDT). DS finds applications in diverse fields such as material inspection, fluid property research, medical diagnostics, cultural heritage restoration, and military defense. The conventional temporal phase-shift (TPS) method encounters limitations in dynamic tests, leading to the introduction of the spatial phase-shift (SPS) method. However, SPS is restricted by aperture size, impacting the phase map quality. The spatial light modulator (SLM) introduces a novel approach to DS system development, enabling quantitative shearing adjustments through precise SLM control. Existing DS systems using traditional phase-shift technology rely on interferometers and struggle to achieve high-quality phase maps with a single exposure. The proposed high-performance DS, leveraging both SLM and a micro-polarizer camera, overcomes this limitation, facilitates single-exposure phase map evaluation with the polarization phase-shift technique, and eliminates the need for a tiny aperture, enhancing light beam utilization and phase map quality.

Breakthrough detection in electrochemical discharge drilling to enhance machining stability

Film cooling holes are widely used in aero-engine turbine blades. These blades feature large numbers of holes with complex angles and require a high level of surface integrity. Electrochemical discharge drilling (ECDD) combines the high efficiency of electrical discharge drilling (EDD) with high quality of electrochemical drilling (ECD). However, due to the existence of a variety of energy for material removal, accurate and timely detection of breakthroughs is fraught with difficulties. An insufficient preset setting distance results in a tiny exit aperture, influencing the structure’s shape. In addition, the electrode is prone to bending at a large overfeeding distance, causing secondary discharge damaging sidewall surface integrity. This paper compares and analyzes the characteristics of processing waveforms using EDD and ECDD. A novel breakthrough detection method is proposed based on the variance signal of average voltage (VSAV) to increase machining stability and achieve fabrication without a recast layer. This method extracts the fluctuation transformation by calculating the variance of the average. Following signal detection, the overfeeding distance is quantified. An experiment is used to validate the breakthrough detection with 100% accuracy in all tests. The optimum overfeeding distances for hole angles of 0 °, 30 °, and 60 ° are obtained, and the stable removal of the recast layer is realized. Finally, the effectiveness of the method is verified on a typical workpiece with a double-wall structure and a nickel-based single crystal blade.

Distribution characteristic of mining-induced horizontal fracture in longwall panel: Field investigation and prediction model

Mining-induced overlying strata fractures have always been the research focus in mining and civil engineering. In this study, the distribution characteristic of mining-induced horizontal fracture was systematically investigated by means of field verification and theoretical analyses in four study area. The following results were obtained: Horizontal fractures mainly occur at rock layer interface with larger aperture caused by uneven settlement between adjacent strata. In addition, a few horizontal fractures can occur in rock layer's interior with tiny aperture. The two-layer structure (i.e., upper- strong and lower- weak rock layer) do not necessarily lead to horizontal fractures along layer interfaces under the effect of coal mining. The improved key stratum theory prediction model (IKS) has significant advantage for predicting the location of horizontal fractures along rock layer interface compared with other models (i.e., Palchik's method, key stratum theory, and maximum curvature method).

Micro-Electro-Mechanical System Fourier Transform Infrared (MEMS FT-IR) Spectrometer Under Modulated-Pulsed Light Source Excitation.

Miniaturized Fourier transform infrared (FT-IR) spectrometers suffer from limited optical throughput due to their tiny aperture size. Therefore, coherent wideband sources with high brightness can provide an advantage over the wideband thermal radiation sources. However, the former ones are available based on pulsed operation. In this work, we present and study a miniaturized FT-IR spectrometer with pulsed light sources including chopped thermal source, semiconductor optical amplifier, Q-switched and femtosecond mode-locked laser sources. A system model for the FT-IR spectrometer system under a modulated input light source is presented. The model accounts for the relatively high scanning speed of the micro-electro-mechanical system (MEMS) interferometer. The signal-to-noise ratio of the spectrometer, due to the light source modulation, is calculated at different values of modulation repetition rate ranging from 20 Hz to 2 MHz, and duty cycle values ranging from 1% to 50%. An analytical expression for the worst-case repetition rate for the spectrometer system is derived. The model results are verified by experimental measurements showing good agreement with the theoretical expectations. Spectroscopic measurements for CO2 gas with pressure ranging from 300 mbar to 700 mbar are also performed using a high-repetition rate source, and the measured spectra agree with the simulation results demonstrating the utility of the spectrometer.

Film Chronicle: 1984 dir. by Michael Radford, and: Eye in the Sky dir. by Gavin Hood, and: The Last Enemy dir. by Iain MacDonald, and: Hamlet dir. by Gregory Doran, and: Hamlet dir. by Michael Almereyda, and: You Were Never Really Here dir. by Lynne Ramsay, and: Caché dir. by Michael Haneke, and: The Lives of Others dir. by Florian

Reviewed by: Film Chronicle: 1984 dir. by Michael Radford, and: Eye in the Sky dir. by Gavin Hood, and: The Last Enemy dir. by Iain MacDonald, and: Hamlet dir. by Gregory Doran, and: Hamlet dir. by Michael Almereyda, and: You Were Never Really Here dir. by Lynne Ramsay, and: Caché dir. by Michael Haneke, and: The Lives of Others dir. by Florian Henckel von Donnersmarck Jefferson Hunter (bio) Film Chronicle: 1984, directed by Michael Radford (Amazon Prime) Eye in the Sky, directed by Gavin Hood (Imports, 2016) The Last Enemy, directed by Iain MacDonald (PBS, 2009) Hamlet, directed by Gregory Doran (BBC Home Entertainment, 2010) Hamlet, directed by Michael Almereyda (Miramax Lionsgate, 2011) You Were Never Really Here, directed by Lynne Ramsay (Lionsgate, 2018) Caché, directed by Michael Haneke (Artificial Eye, 2013) The Lives of Others, directed by Florian Henckel von Donnersmarck (Sony Pictures Home Entertainment, 2007) Do you sense you're being watched? That inconspicuous camera set high up on the building façade, panning relentlessly from side to side—what footage is it recording, and for whom? Is your tablet being tracked? Or the turnpike transponder in your car? What happens with all the personal data you so heedlessly furnish to the internet? In the latest breach of a computer system, did someone hack your social security number? Has the tiny aperture at the top of your laptop screen been opened by a malware worm and is it clandestinely taking pictures of you and recording your voice? How private is your privacy, really? On its way to becoming a mainstay of the contemporary economy (see Shoshana Zuboff's recent book The Age of Surveillance Capitalism), the exposure to onlookers' eyes and listeners' ears has for years now been a daily constant, and for some a cause for concern or anxiety, or even paranoia. Modern-technology-enabled onlookers' eyes and listeners' ears: that is important. In the past surveillance had to be carried out artisanally, for example by watchers with binoculars or shadowers on the street like the trench-coated pair whom Richard Hannay glimpses through the window in Alfred Hitchcock's The 39 Steps. Then later, electronics arrived, and auditory surveillance suddenly became the thing to fear, the bug in the room, the wiretap on the phone line, the unimaginably sensitive directional microphone such as was pointed at the trysting couple in Francis Ford Coppola's The Conversation. Nowadays, thanks to improved technology—CCTV and tracking cookies, one-way mirrors and facial recognition software, drone-mounted sensors and voice-activated recorders—all modes of overseeing and overhearing seem possible, automated ones, improvised ones. Think of the opening scene of John Chu's rom-com Crazy Rich Asians, where the rich boy's new girlfriend is surreptitiously photographed by a passerby pretending to take a selfie on her smartphone. The girlfriend's photo is instantly uploaded to social media, her once-private [End Page 437] identity transformed to a meme. The very latest thing in surveillance is crowdsourcing. The whole world as panopticon . . . No art forms seem better suited to trace the lineaments of this world than film and television, creative modes which are of course camera- and microphone-based themselves, investigations of what can be seen and heard. Screens are good at showing the screens all around our lives and at mimicking technical developments in the art of surveillance; also good, over time, at revealing our varying attitudes to the art. Six decades ago, in Hitchcock's Rear Window, we could applaud the across-the-courtyard snooping of Jimmy Stewart's photo-journalist character because he is tracking the progress of what appears to be a murder. Later, surveillance became permissible as a tool of Lawful Authority. In the opening episodes of David Simon's The Wire, Baltimore detectives listen in on drug dealers' phone calls; in the closing scenes of Alastair Reid's Traffik, a bug is hidden under the desk of the cartel kingpin; and in hundreds of police-procedural television dramas, closed-circuit footage from street cameras leads to quick arrests, usually after the geeks on the squad sharpen up the images with a few keystrokes. Unquestionably, screens can be protective. Think of those shown...

Variable aperture-based ptychographical iterative engine method.

A variable aperture-based ptychographical iterative engine (vaPIE) is demonstrated both numerically and experimentally to reconstruct the sample phase and amplitude rapidly. By adjusting the size of a tiny aperture under the illumination of a parallel light beam to change the illumination on the sample step by step and recording the corresponding diffraction patterns sequentially, both the sample phase and amplitude can be faithfully reconstructed with a modified ptychographical iterative engine (PIE) algorithm. Since many fewer diffraction patterns are required than in common PIE and the shape, the size, and the position of the aperture need not to be known exactly, this proposed vaPIE method remarkably reduces the data acquisition time and makes PIE less dependent on the mechanical accuracy of the translation stage; therefore, the proposed technique can be potentially applied for various scientific researches.

Novel optical super-resolution pattern with upright edges diffracted by a tiny thin aperture.

In the past decade numerous efforts have been concentrated to achieve optical imaging resolution beyond the diffraction limit. In this letter a thin microcavity theory of near-field optics is proposed by using the power flow theorem firstly. According to this theory, the near-field optical diffraction from a tiny aperture whose diameter is less than one-tenth incident wavelength embedded in a thin conducting film is investigated by considering this tiny aperture as a thin nanocavity. It is very surprising that there exists a kind of novel super-resolution diffraction patterns showing resolution better than λ/80 (λ is the incident wavelength), which is revealed for the first time to our knowledge in this letter. The mechanism that has allowed the imaging with this kind of super-resolution patterns is due to the interaction between the incident wave and the thin nanocavity with a complex wavenumber. More precisely, these super-resolution patterns with discontinuous upright peaks are formed by one or three items of the integration series about the cylindrical waves according to our simulation results. This novel optical super-resolution with upright edges by using the thin microcavity theory presented in the study could have potential applications in the future semiconductor lithography process, nano-size laser-drilling technology, microscopy, optical storage, optical switch, and optical information processing.

2.1.2. A Novel Lead(II) MOF Constructed Through 2-Fold Non-linear FDA as Linker

A unique three-dimensional metal-organic framework —— Pb(FDA) (FDA = furan-2,5-dicarboxylic acid) has been hydrothermally synthesized and structurally determined by single-crystal X-ray analysis. The crystal is of tetragonal system, space group I4 1 /a, C 6 H 2 O 5 Pb, Mr = 361.27, a = 13.863(2) A, b = 13.863(2) A, c = 13.998(3) A, V = 2690.0(8) A 3 , Z = 16, Dc = 3.568 g/cm 3 , F(000) = 2560, ?(MuK?) = 25.060 mm-1, Rint = 7.32%, R 1 = 2.59% and wR 1 = 5.88% for 1543 observed reflections with I > 2?(I). Pb cation is six-coordinated by oxygens of FDA, showing the hemi directed geometry. Pb cations are connected into zigzag chain along b direction in bc planar by FDA, which is furthermore linked to three-dimensional framework with very tiny aperture by bridged carboxyl oxygens of FDA. The elemental analyses, PXRD, FTIR spectra and the thermal stability have been structurally characterized.

Submillimeter Coaxial Probes for Dielectric Spectroscopy of Liquids and Biological Materials

In this study, 0.2-mm radius open-ended coaxial probes were constructed and simulated, to measure reference materials and biological media from 1 to 40 GHz. A novel full-wave 3-D model using CST Microwave's frequency-domain solver is demonstrated and the CST example model is provided online to accompany this paper. With this model, design parameters such as the minimum allowable flange radius, short circuit conductivity, and mechanical tolerances were investigated. In terms of measurements, a short-circuit across a tiny aperture was found to be unrepeatable; hence, a calibration technique using only reference liquids is demonstrated. At increasingly smaller radial dimensions, the aperture fields are absorbed by a proportionally smaller volume of material, resulting in microwave hyperthermia of the material. A 3-D and 1-D steady-state heat simulation is utilized to approximate the induced temperature change. Finally, a Monte Carlo technique is used to quantify the errors associated with the aperture models, calibration, and probe imperfections.

10 nm Spatial Resolution Fluorescence Imaging of Single Molecules by Near-Field Scanning Optical Microscopy Using a Tiny Aperture Probe

We demonstrate high-resolution fluorescence imaging of single molecules using near-field scanning optical microscopy (NSOM) with a tiny aperture probe for two different wavelengths in visible range in the illumination mode of operation. The spatial resolutions obtained at both excitation wavelengths were almost the same and the highest resolution realized was about 10 nm. To discuss the achievable resolution in aperture NSOM, we also employed a computer simulation by the finite-difference time-domain method for various aperture sizes and wavelengths. The resolution of 10 nm is predicted to be contributed by the single peak of localized near-field light around the rim of the aperture.

DESIGN AND MODELING OF THERMALLY ACTUATED MICROMIRROR FOR FINE-TRACKING MECHANISM OF HIGH-DENSITY OPTICAL DATA STORAGE

International Journal of Computational Engineering ScienceVol. 04, No. 02, pp. 413-416 (2003) Design, Modelling and SimulationNo AccessDESIGN AND MODELING OF THERMALLY ACTUATED MICROMIRROR FOR FINE-TRACKING MECHANISM OF HIGH-DENSITY OPTICAL DATA STORAGEXIAOCHONG DENG, JIAPING YANG, and TOW CHONG CHONGXIAOCHONG DENGData Storage Institute, A*STAR, DSI Building 5 Engineering Drive 1, Singapore 117608, SingaporeElectrical and Computer Engineering Department, National University of Singapore, 10 Kent Ridge Crescent, Singapore 119260, Singapore Search for more papers by this author , JIAPING YANGData Storage Institute, A*STAR, DSI Building 5 Engineering Drive 1, Singapore 117608, Singapore Search for more papers by this author , and TOW CHONG CHONGData Storage Institute, A*STAR, DSI Building 5 Engineering Drive 1, Singapore 117608, SingaporeElectrical and Computer Engineering Department, National University of Singapore, 10 Kent Ridge Crescent, Singapore 119260, Singapore Search for more papers by this author https://doi.org/10.1142/S146587630300140XCited by:1 PreviousNext AboutSectionsPDF/EPUB ToolsAdd to favoritesDownload CitationsTrack CitationsRecommend to Library ShareShare onFacebookTwitterLinked InRedditEmail AbstractElectro-thermal actuations are very attractive since they can generate larger deflections and forces with low actuating voltages and their fabrication process is compatible with general IC fabrication process. In this paper, a novel micromirror actuated by four thermal bi-layer cantilevers is proposed as a fine-tracking device for high-density optical data storage. Each bi-layer cantilever comprises two material layers with different coefficients of thermal expansion. Due to bimorph effect, the cantilevers bend upwards and downwards an integrated micromirror in the out-of-plane direction. In the modeling of the thermal bi-layer cantilevers, mathematical models are built for both electro-thermal and thermal-mechanical analyses. Furthermore, finite element analysis is performed to evaluate the transient responses and thermal deformations under the actuating voltage and current. The simulation results show that the micromirror can be easily actuated more than 1.5 μm under 1 kHz 4v AC and the first mode resonance frequency is above 18 kHz. Finally, a fabrication process flow of the thermally actuated micromirror (TAM) is proposed. The proposed MEMS device also offers the potential for applications in adaptive optics systems and other optical systems.Keywords:Thermal actuatorMicromirrorOptical data storage References H. Hirano, L.-S. Fan, T. Semba, W. Y. Lee, J. Hong, Micro actuator for tera-storage, Proceedings of MEMS'99, Orlando, FL (Jan, 1999) 441-446 . Google Scholar P. N. Minh, T. Ono, M. Esashi, A novel fabrication method of the tiny aperture tip on silicon cantilever for near field scanning optical microscopy, Proceedings of MEMS'99, Orlando, FL (Jan, 1990) 360-365 . Google ScholarL. P. Ghislainet al., Appl. Phys. Lett. 74(4), 501 (1999). Crossref, Google ScholarY. Yeeet al., Sensors and Actuators A 89, 166 (2001). Crossref, Google ScholarW. Chu, M. Mehregany and R. L. Mullen, J. Micromech. Microeng. 3, 4 (1993). Crossref, Google Scholar FiguresReferencesRelatedDetailsCited By 1A self-sensing thermal actuator incorporating micromirror for tracking mechanism of optical driveJ.P. Yang, X.C. Deng and T.C. Chong Recommended Vol. 04, No. 02 Metrics History KeywordsThermal actuatorMicromirrorOptical data storagePDF download

Groovy Metal Focuses Light

A new theory explains how a series of grooves next to a tiny aperture can prevent light from diverging widely and create a tightly focused beam instead.

The Motion Picture Machine Operator: 1900 to 2000

The motion picture industry has grown from a nickelodeon novelty to one of the greatest art forms in existence. In the final analysis, all production costs, all labors of skilled craftsmen and artists ultimately pass through the tiny aperture of a theater projector for judgment by the audience. An overview of the operator responsible for maintaining a flawless and faithful exhibition of a given production is featured in this paper.

High throughput aperture near-field scanning optical microscopy

This article presents a simple measurement setup for characterization of a combined near-field scanning optical and atomic force microscopy (NSOM/AFM) using an aperture Si based probe. A technological approach has been found for the fabrication of a miniature aperture at the apex of a SiO2 tip on a Si cantilever for NSOM using a “low temperature oxidation and selective etching” (LOSE) technique. The optical transmission efficiency (throughput) of the fabricated probe was measured to be about 10−2 when the aperture size was approximately 100 nm, which is several orders of magnitude higher than that of conventional optical fibers and is also higher than other published throughput on micromachined tips due to a large curvature angle of the SiO2 tip. An extension of the LOSE technique for the fabrication of a tip with a tiny aperture having a metal nanowire at the center of the aperture for a multipurpose NSOM probe is also presented. Using the proposed measurement setup and the fabricated probe, NSOM and corresponding AFM images in contact and tapping modes of several surfaces are obtained.

Microfabrication of miniature aperture at the apex of SiO 2 tip on silicon cantilever for near-field scanning optical microscopy

In this paper we present a novel batch fabrication method of a miniature aperture at the apex of SiO 2 tip on a Si cantilever for near-field scanning optical microscopy (NSOM). The Si cantilever was microfabricated from Si(100) wafer, a SiO 2 pyramidal tip was formed near the end of the Si cantilever by thermal oxidation at low temperature. Due to the effect of locally compressive intrinsic stress, the thermal silicon oxide at the apex is thinner than that at the side wall of the pyramidal etch pit [R.B. Maruss, T.T. Sheng, J. Electrochem. Soc. 129 (6)(1982) 1278–1283; S. Akamine, C.F. Quate, J. Vac. Sci. Technol., B 10 (5)(1992) 2307–2310]. Thus, a tiny aperture can be created at the apex of SiO 2 tip by selective etching the SiO 2 in buffered-HF (BHF) solution. Using this etching method aperture size ranging from 150 to 500 nm have been successfully fabricated. By optimizing the SiO 2 etching time and oxidation condition, sub-100 nm size aperture or aperture array are feasible using the fabrication method. The fabricated probe was combined to an atomic force microscope (AFM) as an AFM/NSOM probe. The AFM in contact mode and corresponding NSOM images of several surfaces were simultaneously obtained. By optimizing the structure of the cantilever we expect to produce a high frequency probe for NSOM, NSOM based data storage and lithography.

Characterization of Materials and Devices by Near-Field Scanning Optical Microscopy

AbstractNear field scanning optical microscopy (NSOM) is a recent technique where a tapered single-mode optical fiber probe is scanned over a sample surface at a height of a fraction of the wavelength. The tapered fiber provides a tiny aperture (a, ˜ 70nm) through which light is coupled and can yield resolutions as high as ˜, λ/40. We have used both room and low-temperature NSOM to study the local spectroscopic characteristics of a wide variety of material systems, from quantum dots and wires, to ordered GaInP, to heterojunctions and optoelectronic devices.Low temperature near-field photoluminescence spectroscopy was used to study spectral emission maps of a set of samples of GaInP epilayers with varying degrees of ordering. The samples exhibit two peaks, a low energy (LE) and a high energy (HE) peak. Our data are inconsistent with expectations that the LE peak is due to emission from domain boundaries and alternative models will be discussed. NSOM spectral maps can yield information about the spatial dependence of the local optical matrix elements. NSOM data on the emission mode structure of strained (In, Ga)As quantum well lasers has yielded new information on the source kinks in the light response at high currents, while local photocurrent spectroscopy using the tip as a point source of photons provides analysis of the semiconductor layer composition.

Photometric Characteristics of Image Dissector Tubes in Photon Counting Operation

Extensive studies on the photometric characteristics and the imaging capability of image dissector tubes, operated under a photon counting scheme in low light level image observation have been carried out. Anode pulse height distribution of the circular aperture (50 µm in diameter) type particularly, shows good agreement with Poisson statistics; its photon counting response as well as its signal-to-noise ratio is considerably better than that of the bigger aperture such the 200×1000 µm2 rectangular type. The spatial resolution is alterable by varying the sampling pixel density. It is, however, limited physically by the size and shape of the aperture. Patterns of various structures have been used in intensity resolution study. Luminous pattern in dark background is likely to give higher intensity resolution than that of dark pattern in luminous background. In general, both the spatial and intensity resolving power of the circular type (tiny aperture) are found to be practically appreciable.

Optical characteristics of a light-focusing fiber guide and its applications

A lenslike glass fiber guide with a parabolic variation of refractive index has been developed. This optical guide named SELFOC® has the following characteristics: simultaneous transmission of laser beams modulated by wide-band signals through narrow space; optical image transmission; realization of a lens with tiny aperture or with extremely short focal length; and the possibility of being bent with a small radius of curvature without spoiling transmission characteristics. In the case of a typical fiber guide with length 1 meter and diameter 0.3 mm, transmission loss is about 0.2 dB and depolarization is about 20 dB at wavelength 0.63μ. The mode pattern of a laser beam after passing through the fiber guide is scarcely deformed. The fiber guide can be used as a transmission line or lens, in optical communication, optical data processing, and optical instruments.

A display for 100 million dots on a five-inch face

The paper describes a microspot tube for ultra-high resolution on a large face. With a spot diameter of 8 microns, the tube can scan a square of 8 cm in 10,000 lines, using 42° magnetic deflection. This is equivalent to the display of 100 million dots on a five-inch face. While the beam power at 20 kilovolts is only 30 mw, the power loading on the screen is 60 kilowatts per square centimeter! Vapor deposited, filmed phosphor developed by Dr. D. Cusano have been found to stand up well under these conditions. The electron-optics includes many novel features. One of these is the use of a resistive helix in the neck which effectively doubles the electrical length of the neck. Another is the use of a tiny object aperture (.0005) which is illuminated by over 20 amperes per square centimeter. This enormous intensity is generated by a microgun which uses a matrix cathode at an emission density of only 2 amperes per square centimeter.