Numerical simulations of laser light guiding and focusing using an open hollow cone

2010 ◽  
Vol 283 (20) ◽  
pp. 3854-3859 ◽  
Author(s):  
Xiahui Zeng ◽  
Dianyuan Fan
Keyword(s):  
Numerical Simulations ◽  
Laser Light ◽  
Hollow Cone

Experiments and Numerical Simulations of water spray by hollow cone nozzle

2018 ◽  
Vol 2018.55 (0) ◽  
pp. E044
Author(s):  
Akira WATANABE ◽  
Mizuki BIZEN ◽  
Koji MATSUBARA ◽  
Yusaku MATSUDAIRA
Keyword(s):  
Numerical Simulations ◽  
Water Spray ◽  
Hollow Cone

Numerical simulations of induced spatial incoherence laser light self‐focusing

1989 ◽  
Vol 1 (12) ◽  
pp. 2437-2449 ◽  
Author(s):  
R. Rankin ◽  
C. E. Capjack ◽  
C. R. James
Keyword(s):  
Numerical Simulations ◽  
Laser Light ◽  
Self Focusing

Nanoshell Assisted Cancer Therapy: Numerical Simulations

2009 ◽  
Author(s):  
Yildiz Bayazitoglu
Keyword(s):  
Cancer Therapy ◽  
Numerical Simulations ◽  
Near Infrared ◽  
Laser Light ◽  
Local Heating ◽  
Thermal Therapy ◽  
Gold Nanoshells ◽  
Comprehensive Treatment ◽  
Embedded Nanoparticles ◽  
Nir Laser

Since the near infrared spectrum (wavelength range of 750–1100 nm) is the region of highest physiological transmisivity, it is the optical communication gateway for the laser energy to propagate into the human body. This optical window also leads to nanoparticle-based approach where embedded nanoparticles absorb the laser light designed to address the specific diagnostic and therapeutic challenges of cancer therapy is exploited extensively in so called plasmonic photo thermal therapy (PPTT). A new tool that is under development for cancer/tumor treatment, in which embedded nanoparticles are manipulated to absorb the Near Infrared (NIR) laser light intensely, aiming at addressing the “nonselectivity” problem that exists in the conventional photo thermal therapy (PPT). The purpose is to seek therapy with a faster and accurate procedure with a comprehensive treatment plan aided with fast and accurate numerical simulations as well. Among all the nanostructures, the noble metal nanoparticles (such as nanoshells) could be tuned to have peak absorption cross section in the NIR spectrum which provide very intense local heating to burn the deeply embedded cancerous tissues and tumors rather than the healthy tissue. Experimental and numerical studies have shown that designed gold nanoshells can be used to remotely and optically induce hyperthermia by embedding certain amount of absorbing dominated gold nanoshells in tumors and then irradiated using NIR laser light. Advancing our capabilities such as modeling, characterization and design of complex nanostructures and their host media for various nanophotonic applications will also increase our effectiveness of induced hyperthermia for its future applications. The computational tools should bridge across the scales from nano to macro, and rapidly compare the predicted behavior of a large number of nanoparticles embedded in tissue so that experimental groups could concentrate laboratory efforts on those resulted configurations most likely to provide optimum results.

Electronic Cone Illumination with the Conventional Transmission Electron Microscope

1977 ◽  
Vol 35 ◽  
pp. 72-73
Author(s):  
William Krakow
Keyword(s):  
Electronic Device ◽  
Chromatic Aberration ◽  
Objective Lens ◽  
Hollow Cone ◽  
Transmission Electron ◽  
Lissajous Figures ◽  
High Resolution Images ◽  
Imaging Mode ◽  
Diffraction Patterns ◽  
Transmission Microscope

An electronic device has been constructed which manipulates the primary beam in the conventional transmission microscope to illuminate a specimen under a variety of virtual condenser aperture conditions. The device uses the existing tilt coils of the microscope, and modulates the D.C. signals to both x and y tilt directions simultaneously with various waveforms to produce Lissajous figures in the back-focal plane of the objective lens. Electron diffraction patterns can be recorded which reflect the manner in which the direct beam is tilted during exposure of a micrograph. The device has been utilized mainly for the hollow cone imaging mode where the device provides a microscope transfer function without zeros in all spatial directions and has produced high resolution images which are also free from the effect of chromatic aberration. A standard second condenser aperture is employed and the width of the cone annulus is readily controlled by defocusing the second condenser lens.

Chronic Laser Exposure Effects on Rabbit Retina

1972 ◽  
Vol 30 ◽  
pp. 54-55
Author(s):  
Burton B. Silver ◽  
Theodore Lawwill
Keyword(s):  
Laser Irradiation ◽  
Laser Light ◽  
Broad Band ◽  
Argon Laser ◽  
Atropine Sulfate ◽  
Ultrastructural Changes ◽  
Laser Exposure ◽  
Rabbit Retina ◽  
Histological Changes ◽  
Threshold Doses

Dutch-belted 1 to 2.5 kg anesthetized rabbits were exposed to either xenon or argon laser light administered in a broad band, designed to cover large areas of the retina. For laser exposure, the pupil was dilated with atropine sulfate 1% and pheny lephrine 10%. All of the laser generated power was within a band centered at 5145.0 Anstroms. Established threshold for 4 hour exposures to laser irradiation are in the order of 25-35 microwatts/cm2. Animals examined for ultrastructural changes received 4 hour threshold doses. These animals exhibited ERG, opthalmascopic, and histological changes consistent with threshold damage.One month following exposure the rabbits were killed with pentobarbitol. The eyes were immediately enucleated and dissected while bathed in 3% phosphate buffered gluteraldehyde.

Experiments in Bright-Field Imaging with Hollow-Cone Illumination

1981 ◽  
Vol 39 ◽  
pp. 226-227
Author(s):  
W. Kunath ◽  
K. Weiss ◽  
E. Zeitler
Keyword(s):  
Signal To Noise Ratio ◽  
Carbon Support ◽  
Electronic System ◽  
Optic Axis ◽  
Hollow Cone ◽  
Signal To Noise ◽  
Bright Field ◽  
Noise Ratio ◽  
Single Field ◽  
Field Imaging

Bright-field images taken with axial illumination show spurious high contrast patterns which obscure details smaller than 15 ° Hollow-cone illumination (HCI), however, reduces this disturbing granulation by statistical superposition and thus improves the signal-to-noise ratio. In this presentation we report on experiments aimed at selecting the proper amount of tilt and defocus for improvement of the signal-to-noise ratio by means of direct observation of the electron images on a TV monitor.Hollow-cone illumination is implemented in our microscope (single field condenser objective, Cs = .5 mm) by an electronic system which rotates the tilted beam about the optic axis. At low rates of revolution (one turn per second or so) a circular motion of the usual granulation in the image of a carbon support film can be observed on the TV monitor. The size of the granular structures and the radius of their orbits depend on both the conical tilt and defocus.

Estimation of the noise in TEM image recorded on “imaging plate”

1987 ◽  
Vol 45 ◽  
pp. 748-749
Author(s):  
T. Oikawa ◽  
N. Mori ◽  
T. Katoh ◽  
Y. Harada ◽  
J. Miyahara ◽  
...  
Keyword(s):  
Low Dose ◽  
Quantum Noise ◽  
Laser Light ◽  
Imaging Plate ◽  
Total System ◽  
Electron Dose ◽  
X Ray ◽  
Image Recording ◽  
Recording Material ◽  
Highly Sensitive

The “Imaging Plate”(IP) is a highly sensitive image recording plate for X-ray radiography. It has been ascertained that the IP has superior properties and high practicability as an image recording material in a TEM. The sensitivity, one of the properties, is about 3 orders higher than that of conventional photo film. The IP is expected to be applied to low dose techniques. In this paper, an estimation of the quantum noise on the TEM image which appears in case of low electron dose on the IP is reported.In this experiment, the JEM-2000FX TEM and an IP having the same size as photo film were used.Figure 1 shows the schematic diagram of the total system including the TEM used in this experiment. In the reader, He-Ne laser light is scanned across the IP, then blue light is emitted from the IP.

Three-fold astigmatism: An important TEM aberration

1993 ◽  
Vol 51 ◽  
pp. 972-973 ◽  
Author(s):  
O.L. Krivanek ◽  
M.L. Leber
Keyword(s):  
High Resolution ◽  
Spatial Frequency ◽  
Field Emission ◽  
Azimuthal Angle ◽  
Hollow Cone ◽  
Small Probe ◽  
Wide Range ◽  
High Resolution Images ◽  
Image Position

Three-fold astigmatism resembles regular astigmatism, but it has 3-fold rather than 2-fold symmetry. Its contribution to the aberration function χ(q) can be written as:where A3 is the coefficient of 3-fold astigmatism, λ is the electron wavelength, q is the spatial frequency, ϕ the azimuthal angle (ϕ = tan-1 (qy/qx)), and ϕ3 the direction of the astigmatism.Three-fold astigmatism is responsible for the “star of Mercedes” aberration figure that one obtains from intermediate lenses once their two-fold astigmatism has been corrected. Its effects have been observed when the beam is tilted in a hollow cone over a wide range of angles, and there is evidence for it in high resolution images of a small probe obtained in a field emission gun TEM/STEM instrument. It was also expected to be a major aberration in sextupole-based Cs correctors, and ways were being developed for dealing with it on Cs-corrected STEMs.

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