Ruby Laser Radiation Research Articles

Nonlinear coloration of photochromic spiropyran solutions

An investigation was made of the two-photon photochromism of spiropyran solutions subjected to ruby laser radiation. The two-photon absorption cross section of spiropyran was calculated. At high laser radiation intensities the dependence of the optical density of the photoinduced form of spiropyran on the incident radiation intensity deviated from the square law. The cause of this deviation was considered.

Selective damage of photosystem I of isolated pea chloroplasts after treatment with ruby laser radiation.

THE primary reactions of photosynthesis in higher plants occur as a result of at least two pigment systems initiating certain photoreactions. The reaction centre of photosystem I (PSI) has maximum absorbance at about 700 nm and is denoted P 700. Photosystem II (PSII) which initiates H2O photolysis and O2 evolution has maximum absorbance at about 650 nm.

Effect of laser irradiation on microstructure and electromigration in aluminum films

Optical and transmission electron microscopy were employed to study the effect of ruby laser irradiation on the microstructure and electromigration properties of thin aluminum films. At low energy levels a single pulse creates multiple regions of localized grain growth; grain size in the irradiated area can be an order of magnitude larger than the matrix. Vaporization, melting, and grain growth are observed and related to the input laser energy. In some cases, the morphology of the laser-damaged film resembles that of cast ingots, i.e., a columnar structure radiating from an equiaxed boundary network and bounded by a circular chill zone. The laser damage was investigated further by exploiting the structure-sensitive nature of electromigration in aluminum film. The morphology of void-hillock formation at the damaged sites provided an additional method for characterizing the mode of structural damage. The electromigration and microscopy data were then combined to propose a structural model for laser-induced damage in aluminum films.

New features of laser-induced gas breakdown in the ultraviolet

A study of gas breakdown induced by the ultraviolet second harmonic of ruby laser radiation has revealed an anomalously high threshold intensity for hydrogen. In addition, it has been demonstrated for the first time that the focal volume dependence of the breakdown threshold, of a number of molecular and noble gases, is influenced by the frequency of the incident radiation.

Electron microscope observation of laser damage on GaAs, GaSb and InSb

Abstract A few of the effects of the ruby laser irradiation on the surface of some III-V semiconducting compounds are studied and discussed. The principal parameters that govern the laser damage are found as the melting temperature and the microhardness.

Laser effect on vital oral tissues: A preliminary investigation

Abstract. A preliminary investigation into the effects of ruby laser radiation from 4 to 40 joule dosages on the incisor teeth, the dorsal surface of the tongue and the auricular skin was carried out on 20 rats. A unique articulating arm was utilized to direct the energy conveniently to the exposed target. A crater was produced in the labial surface of the incisor, and adjacent to the crater the normal appearing enamel was replaced by a glass‐like substance. Severe changes also occupied in the dental pulps, the tongues and the auricular skin. Although the possibility of the clinical application of laser in dentistry is considered to be premature for the time being, data both relevant and interesting enough to encourage further study were obtained.

Surface damage of GaAs from 0.694- and 1.06-μ laser radiation

A study of GaAs surface damage due to ruby and Nd-glass laser radiation is presented. The laser wavelengths chosen represent photon energies both above and below the band gap. Garich material develops on the surface to a greater extent with conventional mode operation than with the Q-switched mode. Although the nature of the surface preparation was seen to influence the damage threshold for the case of Q-switched pulsing, no correlation was found to exist between the threshold and the absence, presence, or type of doping. The damage threshold for Nd-glass laser radiation was approximately 107 W/cm2, only a little higher than that for ruby laser radiation. For Nd-glass laser radiation, the damage appears to be connected with material flaws which are especially susceptible to damage due to their proximity to the surface.

Attenuation of ruby laser radiation in the ground layer of the atmosphere during thermal wavelength drift

Attenuation of ruby laser radiation in the ground layer of the atmosphere during thermal wavelength drift

Intraocular pressure alteration following ruby laser irradiation of the iris.

Intraocular pressure alteration after ruby laser irradiation of rabbit irises was studied using tonometric and manometric methods. These results were compared to those alterations caused by mechanical stimulation with a needle. Following ruby laser impact, the intraocular pressure initially elevated and then decreased before returning to normal. This pattern was found to be similar to the one caused by mechanical stimulation. Topically administered epinephrine suppressed the pressure elevation caused by the ruby laser irradiation. The pressure elevation is thought to be of vascular origin.

Selective Two-Step (STS) Photoionization of Atoms and Photodissociation of Molecules by Laser Radiation

The general considerations for two-step photoionization of atoms and photodissociation of molecules using tunable laser sources are discussed. Experimental results are given for the (1) photoionization of rubidium vapor using a ruby-laser-pumped dye laser and a doubled ruby laser radiation, and (2) photodissociation of HCl using the Raman-shifted output and the fourth harmonic output of a tunable Nd-glass laser. The possibilities for other laser systems are also discussed.

Inhibition of Condensation by Intense Electromagnetic Fields

WE recently described1 an optical etching technique for producing small optical gratings in which a metallic film is used as a Q-switch for a ruby laser system. We have been able to produce line spacings as small as 180 nm using frequency doubled ruby laser radiation in the optical arrangement of Fig. 1; this corresponds to band 13 on Nobert's finest ruled test plate2. With further doubling of the laser light, spacings of order 90 nm should be obtainable.

Motion and Collision of Plasma Blobs Produced by Giant Pulse Laser in a Transverse Magnetic Field

The properties of plasma created by the 200 MW giant pulse ruby laser irradiation on the lithium plate were investigated. Measurements of the variation of the shape and size of the plasma blob with and without the existence of the uniform magnetic field, its density, temperature, pressure, velocity of the motion and the electric field due to the charge separation were made. The phenomena occurring at the head-on collision of two blobs across the uniform magnetic field were also investigated and confirmed that the electric field could be canceled out at the colliding region.

Influence of ruby laser radiation upon the pigmentation apparatus of photosynthesizing organisms

Influence of ruby laser radiation upon the pigmentation apparatus of photosynthesizing organisms

Excitation of luminescence in solutions of terbium and europium chelates under the action of ruby and neodymium laser radiation

Excitation of luminescence in solutions of terbium and europium chelates under the action of ruby and neodymium laser radiation

Phosphosilicate glass stabilization of FET devices : P. Balk and J. M. Eldridge, Proc. IEEE57, No. 9, September (1969), p. 1558

Successful incorporation of laser annealing techniques into standard processing methods requires that the electrical characteristics of the devices not be degraded. In this work, a range of energy densities from pulsed u.v. and visible lasers which can be utilized in silicon on sapphire (SOS) technology to improve device performance without introducing any deleterious side effects is determined experimentally. Silicon islands were photolithographically defined and chemically etched (KOH) on standard SOS wafers which were subsequently exposed to pulsed (25 nsec) ruby (λ = 6943 Å) and excimer (λ = 2490 Å) laser radiation. Comparative studies of the effect of front and back side (through the sapphire) irradiation of the silicon on device performance were conducted. Using standard processing techniques, MOS transistors were fabricated after laser irradiation and electrically characterized. It was found that under certain conditions utilization of lasers in SOS processing, can result in an increase in the interface state density at both the top 〈100〉 Si-SiO2 interface and the bottom Al2O3-Si interface. However, a set of conditions exists, in which it is possible to apply laser annealing to standard SOS processing so as to increase MOS/SOS transistor channel mobility by over 30% without causing any degradation of the device electrical characteristics.

Optical constants of fully ionized hydrogen plasma for laser radiation

The refractive index n and the absorption constant K are numerically evaluated for fully ionized hydrogen plasmas as functions of the electron temperature T and atomic density N for the case of ruby, neodymium-glass, and CO2 laser radiation and for the second harmonics of each type of radiation on the basis of the two-fluid model of hydrodynamics using Spitzer's collision frequency. Limitations due to degeneration, too small Debye length, and non-linear effects are given. The absorption constant is compared with the values of the quantum theory of inverse bremsstrahlung without collective effects, and with the Dawson-Oberman theory.

Laser-induced cataract. Clinical observations.

Ocular exposure to high levels of unfocused, pulsed, ruby laser radiation results in cataract formation when pupillary miosis is induced prior to irradiation. The clinical course and characteristics of these lens opacities, and of the accompanying ophthalmic sequelae, are described.

Interaction of High-Power Ruby-Laser Light Pulses with Metal Colloids in Transparent Crystals

The effects of intense Q-switched ruby laser radiation on the colloidal systems NaCl[Au] and CaF2[Ca] were investigated by microscope and absorption spectroscopy techniques. A dependence of the width and depth of the surface crater on the incident laser pulse energy was established. In the case of NaCl[Au] a shift of the absorption maximum towards shorter wavelengths was observed. This was interpreted in terms of Mie's theory. Calculations on the temperatures generated in the colloids and its surroundings were done using Goldenberg's theoretical results.

Laser saturation of optical transitions in a starch component: the amylose-iodine-iodide complex.

Abstract— Saturation of optical absorption by an aqueous solution of the amylose‐iodine‐iodide complex was observed. Transmission of ruby laser radiation as a function of incident laser power density was measured and fitted to the steady‐state solution of a double‐absorption rate‐equation model. This study gave an indirect determination of the lifetime of the first excited energy level. The material behaved as a passive Q‐switch for a ruby laser.

Nonlinear Absorption Behavior of Indanthrone Dyes: Comparison of Optical Saturation and Photochemical Processes

The nonlinear absorption of ruby laser radiation by indanthrone dyes resulted in significant temporal shaping of the transmitted laser pulse at incident flux densities greater than 30 MW/cm2. This behavior and the observation that aggregation of the dye molecules is associated with the nonlinear response indicates that photochemical processes may be responsible for the effect. Models involving such processes were analyzed and the results compared to the experimental data.