EFFECT OF THE RUBY LASER MICROBEAM ON MITOCHONDRIA OF KB CELLS SUPRAVITALLY STAINED BY PINACYANOL

With pinacyanol as the supravital stain, a preferential effect on mitochondria of KB cells was achieved by the irradiation with the ruby laser beam. The observation confirmed the results of other workers using janus green B in the same experimental system. The preferential effect on mitochondria was noted in the area extending 8–10 µ beyond the nonpreferential damage of 4–5 µ in diameter. The opaque material associated with mitochondria possibly represented coagulated protein. The effect involved cristae mitochondriales without severe disarrangement of their structure. The opaque material could be interpreted as the result of direct interaction between mitochondria and the laser beam, even though the mitochondria were noted outside of the previously estimated focal spot size of about 3 µ Within the thickness of 2–4 µ of monolayered cells, larger areas of damage can be accounted for by divergence of the beam which is focused by a microscope objective of very short focal length. A threshold of biologic effectiveness is probably also involved.

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Self-Focusing of Hermite-Cosh-Gaussian Laser Beams in Plasma under Density Transition

Advances in Optics ◽

10.1155/2014/942750 ◽

2014 ◽

Vol 2014 ◽

pp. 1-5 ◽

Cited By ~ 8

Author(s):

Manzoor Ahmad Wani ◽

Niti Kant

Keyword(s):

Laser Beam ◽

Plasma Density ◽

Focal Spot ◽

Beam Width ◽

Spot Size ◽

Laser Beams ◽

Equation Approach ◽

Focal Spot Size ◽

Self Focusing ◽

Small Spot

Self-focusing of Hermite-Cosh-Gaussian (HChG) laser beam in plasma under density transition has been discussed here. The field distribution in the medium is expressed in terms of beam-width parameters and decentered parameter. The differential equations for the beam-width parameters are established by a parabolic wave equation approach under paraxial approximation. To overcome the defocusing, localized upward plasma density ramp is considered, so that the laser beam is focused on a small spot size. Plasma density ramp plays an important role in reducing the defocusing effect and maintaining the focal spot size up to several Rayleigh lengths. To discuss the nature of self-focusing, the behaviour of beam-width parameters with dimensionless distance of propagation for various values of decentered parameters is examined by numerical estimates. The results are presented graphically and the effect of plasma density ramp and decentered parameter on self-focusing of the beams has been discussed.

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Laser beam zooming and deflection using a nonlinear metamaterial refracting medium

EPJ Applied Metamaterials ◽

10.1051/epjam/2018003 ◽

2018 ◽

Vol 5 ◽

pp. 8

Author(s):

Andrew James Comley

Keyword(s):

Laser Beam ◽

Inertial Confinement Fusion ◽

Analytical Approach ◽

Focal Spot ◽

Spot Size ◽

Inertial Confinement ◽

Lower Intensity ◽

Focal Spot Size ◽

Confinement Fusion ◽

Nonlinear Metamaterial

In-process control of the focal spot size and pointing position of a laser as it interacts with a target (beam zooming and deflection) offers the possibility of unprecedented efficiency improvements in a number of applications, such as inertial confinement fusion and laser micromachining. Here is described a system in which the focussing characteristics of a laser beam at one wavelength can be controlled by a lower-intensity beam at another wavelength, via their mutual interaction with a nonlinear metamaterial refracting medium. Such a metamaterial approach permits the optical response of the medium to be tailored according to the wavelengths of interest and time response required in a given application. A metamolecule unit cell design is described in terms of an equivalent circuit based on a pair of LCR (inductance, capacitance, resistance) circuits coupled by a common nonlinear capacitor. The circuit is studied using an analytical approach to obtain an understanding of its properties and design relationships between circuit parameters. Potential realisations of the circuit are discussed.

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Energiebestimmung der Stoßwelle eines laserinduzierten Gasdurchbruchs

Zeitschrift für Naturforschung A ◽

10.1515/zna-1969-0812 ◽

1969 ◽

Vol 24 (8) ◽

pp. 1244-1249 ◽

Cited By ~ 1

Author(s):

K Hohla ◽

K Büchl ◽

R Wienecke ◽

S Witkowski

Keyword(s):

Laser Beam ◽

Shock Front ◽

High Speed ◽

Ruby Laser ◽

Focal Length ◽

Gas Pressure ◽

Pressure Chamber ◽

Image Converter ◽

Shadow Method ◽

Gas Breakdown

AbstractA gas breakdown was produced in the gases H2, N2 , He, Ar and Xe with a 100 MW ruby laser in a pressure chamber, the gas pressure being varied from 200 Torr to 10 atm. A lense with a focal length of 16 mm was used for focusing the laser beam. The blastwave was observed using the shadow method. High-speed pictures and streak pictures of the blastwave were taken with an image converter camera. The shape of the blastwave was approximately spherical. The position of the shock-front was determined as a function of time by streak pictures and compared with Sakurai's theory for H2 and N2 for Mach numbers M ≧ 2 and for Xe, Ar and He for M ≧ 4. From the normalization parameter it is possible to determine the energy of the blastwave for various gases as a function of the pressure of the gases. In the gases He and H2 pronounced rise of the blastwave energy was found with rising pressure. However, in the gases N2 , Xe and Ar there exists a maximum in the blastwave energy at a pressure of approximately 1 atm. A preliminary explanation for this behaviour is given.

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A High Resolution Scanning Microscope

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100101529 ◽

1968 ◽

Vol 26 ◽

pp. 356-357

Author(s):

A. V. Crewe ◽

J. Wall ◽

L. M. Welter

Keyword(s):

High Resolution ◽

Field Emission ◽

Spherical Aberration ◽

Focal Length ◽

Spot Size ◽

Emission Source ◽

Field Of View ◽

Scanning Microscope ◽

Magnetic Lens ◽

High Quality

A scanning microscope using a field emission source has been described elsewhere. This microscope has now been improved by replacing the single magnetic lens with a high quality lens of the type described by Ruska. This lens has a focal length of 1 mm and a spherical aberration coefficient of 0.5 mm. The final spot size, and therefore the microscope resolution, is limited by the aberration of this lens to about 6 Å.The lens has been constructed very carefully, maintaining a tolerance of + 1 μ on all critical surfaces. The gun is prealigned on the lens to form a compact unit. The only mechanical adjustments are those which control the specimen and the tip positions. The microscope can be used in two modes. With the lens off and the gun focused on the specimen, the resolution is 250 Å over an undistorted field of view of 2 mm. With the lens on,the resolution is 20 Å or better over a field of view of 40 microns. The magnification can be accurately varied by attenuating the raster current.

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Computational Technique for the Qualification of Focal Spot Size and Shape of Industrial Radioscopy Equipment Using Star Patterns

Materials Evaluation ◽

10.32548/2020.me-04044 ◽

2020 ◽

Vol 78 (4) ◽

pp. 479-486

Author(s):

Marcela Tatiana Fernandes Beserra ◽

◽

Ricardo Tadeu Lopes ◽

Davi Ferreira de Oliveira ◽

Claudio Carvalho Conti ◽

...

Keyword(s):

Focal Spot ◽

Spot Size ◽

Computational Technique ◽

Focal Spot Size ◽

Size And Shape

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Spot size and effective focal length measurements for a fast axial flow CO2 laser

10.2351/1.5059610 ◽

1997 ◽

Author(s):

Robert J. Steele ◽

Phillip W. Fuerschbach ◽

Danny O. MacCallum

Keyword(s):

Co2 Laser ◽

Focal Length ◽

Axial Flow ◽

Spot Size ◽

Effective Focal Length ◽

Length Measurements

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Localized Die Metallization Damage Induced During Laser-Marking of a Semiconductor Package

ISTFA 2007: Conference Proceedings from the 33rd International Symposium for Testing and Failure Analysis ◽

10.31399/asm.cp.istfa2007p0226 ◽

2007 ◽

Author(s):

Paul Eric B. Parañal

Keyword(s):

Laser Beam ◽

Direct Interaction ◽

Silica Spheres ◽

Layer By Layer ◽

Laser Marking ◽

Molding Compound ◽

Molding Material ◽

Die Surface ◽

Passivation Layers ◽

Propagation Medium

Abstract This paper presents a new fail mechanism for laser-marking induced die damage. Discovered during package qualification, silica spheres – commonly used as fillers in the molding material, was shown to act as a propagation medium that promote the direct interaction of the scribing laser beam and the die surface. Critical to the understanding of the fail mechanism is the deprocessing technique devised to allow layer by layer examination of the metallization and passivation layers in an encapsulated silicon die. The technique also made possible the inspection of the molding compound profile directly on top of the affected die area.

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Dependence of laser accelerated protons on laser energy following the interaction of defocused, intense laser pulses with ultra-thin targets

Laser and Particle Beams ◽

10.1017/s0263034611000395 ◽

2011 ◽

Vol 29 (3) ◽

pp. 345-351 ◽

Cited By ~ 22

Author(s):

C.M. Brenner ◽

J.S. Green ◽

A.P.L. Robinson ◽

D.C. Carroll ◽

B. Dromey ◽

...

Keyword(s):

Laser Pulse ◽

Focal Spot ◽

Laser Pulse Energy ◽

Laser Energy ◽

Spot Size ◽

Proton Flux ◽

Focal Spot Size ◽

Order Of Magnitude ◽

Laser Focal Spot ◽

Accelerated Protons

AbstractThe scaling of the flux and maximum energy of laser-driven sheath-accelerated protons has been investigated as a function of laser pulse energy in the range of 15–380 mJ at intensities of 1016–1018 W/cm2. The pulse duration and target thickness were fixed at 40 fs and 25 nm, respectively, while the laser focal spot size and drive energy were varied. Our results indicate that while the maximum proton energy is dependent on the laser energy and laser spot diameter, the proton flux is primarily related to the laser pulse energy under the conditions studied here. Our measurements show that increasing the laser energy by an order of magnitude results in a more than 500-fold increase in the observed proton flux. Whereas, an order of magnitude increase in the laser intensity generated by decreasing the laser focal spot size, at constant laser energy, gives rise to less than a tenfold increase in observed proton flux.

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Expansion of a Focused Laser Beam in the Turbulent Atmosphere

Canadian Journal of Physics ◽

10.1139/p71-148 ◽

1971 ◽

Vol 49 (10) ◽

pp. 1233-1248 ◽

Cited By ~ 5

Author(s):

A. D. Varvatsis ◽

M. I. Sancer

Keyword(s):

Laser Beam ◽

Free Space ◽

Turbulent Atmosphere ◽

Focal Plane ◽

Spot Size ◽

Small Aperture ◽

Forward Scatter ◽

Green’S Theorem ◽

Focused Beams ◽

Weakly Dependent

This work examines the expansion of a focused laser beam in the turbulent atmosphere. The formulation is based on Green's theorem and the valid assumption that the turbulent atmosphere is a forward-scatter medium for wavelengths of interest (0.6 μ < λ < 11 μ). The main results are: (1) the spot size at the free-space focal plane in the presence of turbulence is independent of the aperture radius, and is only weakly dependent on the wavelength, (2) the focal plane can be significantly shifted for small aperture radii, short wavelengths, and long free-space focal lengths, (3) the effect of the atmosphere is pronounced only close to the free-space focus and very far away, and (4) the turbulent atmosphere has a stronger effect on weakly focused beams rather than strongly focused beams, except very close to the free-space focus, where the effect is more pronounced for strongly focused beams.

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