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Results for “Optical Devices”

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At least 1,567 records · Page 87Linked to original sources
PubMed2005

Spectroscopic characterization of two different microwave (2.45 GHz) induced argon plasmas at atmospheric pressure.

A surface-wave-sustained discharge created by using a surfatron device in a tube open to the atmosphere can be used to maintain a microwave (2.45 GHz) plasma at atmospheric pressure at powers of less than 300 W. The TIA (Torche a Injection Axiale) is a device also producing a plasma that, moreover, permits us to work at high power (higher than 200 W and up to 1000 W). A study of the departure from the thermodynamic equilibrium existing in the argon plasmas created by both devices has been done by using optical emission spectroscopy techniques in order to characterize them and to evaluate their possible advantages when they are used for applied purposes.

Argon↗
PubMed2006

Spatially and temporally synchronized atomic force and total internal reflection fluorescence microscopy for imaging and manipulating cells and biomolecules.

The atomic force microscope is a high-resolution scanning-probe instrument which has become an important tool for cellular and molecular biophysics in recent years but lacks the time resolution and functional specificities offered by fluorescence microscopic techniques. To exploit the advantages of both methods, here we developed a spatially and temporally synchronized total internal reflection fluorescence and atomic force microscope system. The instrument, which we hereby call STIRF-AFM, is a stage-scanning device in which the mechanical and optical axes are coaligned to achieve spatial synchrony. At each point of the scan the sample topography (atomic force microscope) and fluorescence (photon count or intensity) information are simultaneously recorded. The tool was tested and validated on various cellular (monolayer cells in which actin filaments and intermediate filaments were fluorescently labeled) and biomolecular (actin filaments and titin molecules) systems. We demonstrate that with the technique, correlated sample topography and fluorescence images can be recorded, soft biomolecular systems can be mechanically manipulated in a targeted fashion, and the fluorescence of mechanically stretched titin can be followed with high temporal resolution.

Actin Cytoskeleton↗
PubMedDate not supplied

The "sandwich technique" for iris-fixated phakic intraocular lens implantation.

PURPOSE: To describe a new technique of implantation of the Artisan/Verisyse phakic intraocular lens (PIOL). METHODS: After PIOL insertion into the anterior chamber, a bolus of a high viscosity ophthalmic viscosurgical device (OVD) is placed over the optic, separating it widely from the endothelium. RESULTS: The technique decreases the chance of endothelial damage during enclavation. CONCLUSIONS: A bolus of a high viscosity OVD placed on the anterior surface of the Artisan/Verisyse PIOL may make enclavation safer.

Anterior Chamber↗
PubMedDate not supplied

Information partnerships--shared data, shared scale.

How can one company gain access to another's resources or customers without merging ownership, management, or plotting a takeover? The answer is found in new information partnerships, enabling diverse companies to develop strategic coalitions through the sharing of data. The key to cooperation is a quantum improvement in the hardware and software supporting relational databases: new computer speeds, cheaper mass-storage devices, the proliferation of fiber-optic networks, and networking architectures. Information partnerships mean that companies can distribute the technological and financial exposure that comes with huge investments. For the customer's part, partnerships inevitably lead to greater simplification on the desktop and more common standards around which vendors have to compete. The most common types of partnership are: joint marketing partnerships, such as American Airline's award of frequent flyer miles to customers who use Citibank's credit card; intraindustry partnerships, such as the insurance value-added network service (which links insurance and casualty companies to independent agents); customer-supplier partnerships, such as Baxter Healthcare's electronic channel to hospitals for medical and other equipment; and IT vendor-driven partnerships, exemplified by ESAB (a European welding supplies and equipment company), whose expansion strategy was premised on a technology platform offered by an IT vendor. Partnerships that succeed have shared vision at the top, reciprocal skills in information technology, concrete plans for an early success, persistence in the development of usable information for all partners, coordination on business policy, and a new and imaginative business architecture.

Economic Competition↗
PubMedDate not supplied

[Digital fluorograph with automatic exposition].

Discussed in the paper is a system of automatic exposition choice in a digital fluorograph designed by the "Gelpik" company, Moscow. The perspective equipment variation is as follows: intensifying screen + optic system + charge-communication device-matrix.

Fluoroscopy↗
PubMedDate not supplied

Analysis of methods to assess frontal sinus extent in osteoplastic flap surgery: transillumination versus 6-ft Caldwell versus image guidance.

BACKGROUND: The aim of this study was to compare three common methods (transillumination, plain radiographs, and computerized tomography [CT] image guidance) for estimating the position and extent of pneumatization of the frontal sinus in osteoplastic flap surgery. METHODS: Axial CT scans and 6-ft Caldwell radiographs were performed on 10 cadaver heads. For each head, soft tissue overlying the frontal bone was raised and the anticipated position and extent of the frontal sinus at four points was marked using three common methods. The silhouette of the frontal sinus from the Caldwell plain radiograph was excised and placed in position. Four points at the periphery also were made using information obtained from a passive optically guided image-guided surgery device, and transillumination via a frontal trephination also was used to estimate sinus extent. The true sinus size was measured at each point and compared with experimental values. RESULTS: The use of CT image guidance generated the least difference between measured and actual values (mean = 1.91 mm; SEM = 0.29); this method was found statistically superior to Caldwell (p = 0.040) and transillumination (p = 0.007). Image guidance did not overestimate the size of the sinus (0/36) and was quicker than the Caldwell approach (8.5 versus 11.5 minutes). There was no learning curve appreciated with image guidance. CONCLUSION: Accurate and precise estimation of the position and extent of the frontal sinus is crucial when performing osteoplastic flap surgery. Use of CT image guidance was statistically superior to Caldwell and transillumination methods and proved to be safe, reproducible, economic, and easy to learn.

Cadaver↗
PubMed1989

Improved resolution of specular micrographs.

The purpose of specular photomicrography of the corneal endothelium is to depict fine cellular morphology and to determine total cell density. The use of silver-based photographic films to record the cells and generate enlarged paper prints yields the highest resolution currently possible. Previously, the quality of these prints was diminished when the highly resolved cell image was combined with the standardized grid used for quantification, since the sub-optimal quality of the grid's plastic substrate caused optical aberrations. We present a prototype device and a modified technique that enables the full resolution of the microscope to be represented on photographic prints and allows highly detailed views of the endothelial mosaic to be depicted with or without the standardized grid.

Endothelium, Corneal↗
PubMed1993

Ophthalmic lenses for athletes and sportsmen.

This paper describes a protocol for prescribing and dispensing ophthalmic products to athletes and sportsmen and provides a description of lens characteristics and properties that are generic for the needs of sports-minded patients. Technical information on lens materials, treatments, dyes, and coatings essential for the prescribing and dispensing of ophthalmic products to athletes are discussed in the context of this protocol. Knowledge of ophthalmic lens standards, especially those that pertain to impact resistance and radiant energy attenuation, are also described. A sports lens selection checklist is provided for dispensers who apply this protocol to the selection of appropriate eyewear for athletically inclined patients.

Eye Protective Devices↗
PubMed1977

[Reproducibility and accuracy of an optical ssd pointer (author's transl)].

The reproducibility and accuracy of an optical source-surface distance measuring device was systematically examined. The standard deviation of twenty equal distance settings was +/-0,5%. The error in dose-rate caused by one single adjustment did not exceed +/-2%. The position of the effective source-center is defined by a special inverse square plot. A periodical check is recommended.

Mathematics↗
PubMedDate not supplied

[Torsional movements of the human eye. I. Torsional movements on inclining the head towards the shoulder].

The characteristics of the torsional eye movements during head tilting were investigated. Different conditions were used in the experiments. The subjects were in sitting and lying positions in the light and in the dark. A new method of recording with the suction device of Yarbus and the simple optical system allowed to have records without some redundant components of movement. This made record processing less complex and more accurate. The torsional drift in the slow phase of the eye movement was found present under any conditions. When being recorded simultaneously both eyes in man were in identical and synchronous movement.

Eye Movements↗
PubMed2006

Photoconductive optically driven deformable membrane for spatial light modulator applications utilizing GaAs substrates.

The fabrication and characterization of an optically addressable deformable mirror for a spatial light modulator is described. Device operation utilizes an electrostatically driven pixellated aluminized polymeric membrane mirror supported above an optically controlled photoconductive GaAs substrate. A 5 microm thick grid of patterned photoresist supports the 2 microm thick aluminized Mylar membrane. A conductive ZnO layer is placed on the back side of the GaAs wafer. A standard Michelson interferometer is used to measure mirror deformation data as a function of illumination, applied voltage, and frequency. A simplified analysis of device operation is also presented.

Journal Article↗
PubMed2005

A microfabricated capillary electrophoresis chip with multiple buried optical fibers and microfocusing lens for multiwavelength detection.

We present a new microfluidic device utilizing multiwavelength detection for high-throughput capillary electrophoresis (CE). In general, different fluorescent dyes are only excited by light sources with appropriate wavelengths. When excited by an appropriate light source, a fluorescent dye emits specific fluorescence signals of a longer wavelength. This study designs and fabricates plastic micro-CE chips capable of performing multiple-wavelength fluorescence detection by means of multimode optic fiber pairs embedded downstream of the separation channel. For detection purposes, the fluorescence signals are enhanced by positioning microfocusing lens structures at the outlets of the excitation fibers and the inlets of the detection fibers, respectively. The proposed device is capable of detecting multiple samples labeled with different kinds of fluorescent dyes in the same channel in a single run. The experimental results demonstrate that various proteins, including bovine serum albumin and beta-casein, can be successfully injected and detected by coupling two light sources of different wavelengths to the two excitation optic fibers. Furthermore, the proposed device also provides the ability to measure the speed of the samples traveling in the microchannel. The developed multiwavelength micro-CE chip could have significant potential for the analysis of DNA and protein samples.

Electrophoresis, Capillary↗
PubMed2005

In vivo fluorescence detection of glucose using a single-walled carbon nanotube optical sensor: design, fluorophore properties, advantages, and disadvantages.

In this work, several aspects of in vivo glucose detection using a nanotube-based optical sensor are considered. The optical properties of commonly used organic and nanoparticle fluorescent probes are compared with respect to quantum yield, human tissue penetration, and photobleaching stability. The latter two factors are shown to dominate sensor viability and require a near-infrared nanoparticle fluorophore for practical device operation. The dynamics of a model optical sensor are compared to a flux-measuring electrochemical sensor of equal area using a mathematical simulation of a healthy patient ingesting three predefined meals per day. Both sensors demonstrate an approximately linear response to blood glucose levels. It is shown that the optical sensor, which transduces glucose concentration, not flux, directly is significantly more stable to membrane biofouling.

Biosensing Techniques↗
PubMed2001

Interference-based detection of nucleic acid targets on optically coated silicon.

Sequence-specific detection of polynucleotides typically requires modified reporter probes that are labeled with radioactive, fluorescent, or luminescent moieties. Although these detection methods are capable of high sensitivity, they require instrumentation for signal detection. In certain settings, such as clinical point of care, instrumentation might be impractical or unavailable. Here we describe a detection approach in which formation of a nucleic acid hybrid is enzymatically transduced into a molecular thin film that can be visually detected in white light. The system exploits a flat, optically coated silicon-based surface to which capture oligonucleotides are covalently attached. The optimized system is capable of detection of nucleic acid targets present at sub-attomole levels. To supplement visual detection, signals can be quantitated by a charge-coupled device. The design and composition of the optical surface, optimization of immobilization chemistry for attachment of capture probes, and characterization of the efficiency of the hybridization process are presented. We describe the application of this system to detection of a clinically relevant target, the mecA gene present in methicillin-resistant Staphylococcus aureus.

Base Sequence↗
PubMed1996

Enzyme-linked immunosorbent assay by image analysis using a charge-coupled device array detector.

This paper describes a fluorescence enzyme-linked immunosorbent assay (ELISA) for the quantification of (+/-)-2-(2, 4-dichlorophen-oxy)propionic methyl ester (dichlorprop methyl ester). Antibodies for dichlorprop methyl ester were produced by immunizing rabbits with a conjugate of dichlorprop methyl ester with bovine serum albumin. Data acquisition on microtiter wells is performed by a spectrofluorometer through a fiber optic and by a charge-coupled device camera. A correlation was obtained between the image analysis data on ELISA and the data acquired by the spectrofluorometer. The results demonstrate that the fluorescence image analysis performed by the charge-coupled device detector is applicable to ELISA, and the analysis time, sensitivity, and precision of the ELISA procedure are compared to conventional fluorescence ELISA performed by the spectrofluorometer. The ELISA procedure was selective for structurally similar compounds or usually found in formulation pesticides. Concentrations for 50% displacement curves were dichlorprop, 83.59 microg/ml, and 2,4,5-T, 388.23 microg/ml; triclopyr, ioxynil, bentazone, and MCPA had no response.

2,4-Dichlorophenoxyacetic Acid↗
PubMed2005

A polymeric master replication technology for mass fabrication of poly(dimethylsiloxane) microfluidic devices.

A protocol of producing multiple polymeric masters from an original glass master mold has been developed, which enables the production of multiple poly(dimethylsiloxane) (PDMS)-based microfluidic devices in a low-cost and efficient manner. Standard wet-etching techniques were used to fabricate an original glass master with negative features, from which more than 50 polymethylmethacrylate (PMMA) positive replica masters were rapidly created using the thermal printing technique. The time to replicate each PMMA master was as short as 20 min. The PMMA replica masters have excellent structural features and could be used to cast PDMS devices for many times. An integration geometry designed for laser-induced fluorescence (LIF) detection, which contains normal deep microfluidic channels and a much deeper optical fiber channel, was successfully transferred into PDMS devices. The positive relief on seven PMMA replica masters is replicated with regard to the negative original glass master, with a depth average variation of 0.89% for 26-microm deep microfluidic channels and 1.16% for the 90 mum deep fiber channel. The imprinted positive relief in PMMA from master-to-master is reproducible with relative standard deviations (RSDs) of 1.06% for the maximum width and 0.46% for depth in terms of the separation channel. The PDMS devices fabricated from the PMMA replica masters were characterized and applied to the separation of a fluorescein isothiocyanate (FITC)-labeled epinephrine sample.

Dimethylpolysiloxanes↗