Power Argon Laser Research Articles

Bio-inspired synthesis of silver nanoparticles using Hibiscus Tiliaceus L. flower extracts for improved optical characteristics

In this work, we report a simple, facile, environment friendly and green approach to synthesize silver nanoparticles using aqueous flower extracts of Hibiscus Tiliaceus L. The morphology (shape/size) and crystal structure of as-synthesized silver nanoparticles (NPs) were determined by transmission electron microscopy and x-ray diffraction. The UV–Vis spectroscopy was used to record the surface plasmon resonance peak, while spectro-fluorophotometry was used to examine the fluorescence emission spectra of silver NPs. Moreover, the optical nonlinearities of silver NPs were investigated using z-scan technique with low power argon laser beam at wavelengths 488 nm and 514 nm in continuous-wave regime and at 532 nm in the pulsed laser regime. Our results indicate that the nonlinear absorption in silver NPs is reverse saturation absorption of the order of 10–3 cm/W and the negative nonlinear refractive index was determined as of the order of 10–8 cm2/W. Moreover, the optical nonlinear properties were used to demonstrate optical limiting abilities of the synthesized silver NPs. The results presented in this study indicate that bio-synthesized silver NPs are excellent candidates as a nonlinear material and can be widely used for waveguide applications.

Short-wavelength phase-change optical data storage in In-Sb-Te alloy films

Physical properties of In-Sb-Te thin films prepared by D.C. magnetron sputtering method are studied. X-ray diffraction and differential scanning calorimetry (DSC) results indicate that the crystallization temperature and the activation energy of In 47Sb 14Te 39 thin films are about 300°C and 2.9 eV, respectively. The crystallization compounds of In 47Sb 14Te 39 thin films mainly consist of In 3SbTe 2 with small amounts of InTe and In 2Te 3. Optical recording test of the films clearly shows that larger reflectivity contrast can be obtained by lower power argon laser (514.5 nm) irradiation. These results demonstrate that the ternary composition film is a promising candidate for short-wavelength direct overwritable phase-change optical data storage.

Optical and Short-Wavelength Recording Properties of InSbTe Phase Change Thin Films

Optical absorption spectra of InSbTe thin films prepared by the dc magnetron sputtering methods are studied. The absorption increases with the decrease of wavelength in the range 400 to 1000 nm. There is a comparatively large absorption in the region 400 to 600 nm compatible with the wavelengths of argon laser which is the typical short-wavelength optical recording source. Optical storage performance of the films clearly shows that larger reflectivity contrast can be obtained at lower power argon laser (514.5 nm) irradiation. These results demonstrate that the InSbTe film is a promising candidate for short-wavelength direct overwritable phase change optical storage.

Rotational Raman scattering in the instructional laboratory

We describe the use of a single spectrometer and a low power argon laser for the study of the pure rotational Raman spectra of H2, O2, N2, and CO2. Analyses of the spectra allow the student to obtain internuclear separations in the ground state, the rotational temperature of the gas, and the influence of nuclear spin on the allowed rotational states. The four molecules chosen for study have nuclei with spins of I=0 (O2), 1/2 (H2), and 1 (N2) and thus the discussion includes the effects of both Bose and Fermi exchange properties on the symmetry of the overall wave function. To fully illustrate the range of information available from the data, we provide spectra obtained with a high quality double spectrometer which allow even the lowest rotational states to be observed and show the stretching of the H2 molecule due to centripetal forces.

Long‐term efficacy of low power argon laser trabeculoplasty

We studied the long-term efficacy of argon laser trabeculoplasty, applying low-power (a mean of 450 mW), a duration of 0.1 second, and a small number of burns (a mean total energy of 1.85 J) over 90 to 120 degrees of the trabecular meshwork. Fifty-four eyes with poorly controlled open-angle glaucoma were treated. The mean follow-up was 46 months. The mean intraocular pressure decrease was 5.3 mmHg in 35 eyes at one year, 6.1 mmHg in 23 eyes at 3 years, 5.1 mmHg in 13 eyes at 5 years, and 5.4 mmHg in 5 eyes at 6 years. Life-table analysis showed that the probability of success was 58% at one year, 49% at 3 years, and 46% at 5 years. Both the incidence and magnitude of the intraocular pressure rise in the early post-laser period were minimal and no serious complications were observed.

SUPPRESSION OF HIPPOCAMPAL EPILEPTIFORM ACTIVITY IN VITRO AFTER LASER EXPOSURE

Extracellular field potentials were recorded in the stratum pyramidale of CA3 in hippocampal slices prepared from male Sprague-Dawley rats. Electrical stimuli were delivered to s. radiatum of CA3. After stable responses were established, stimulus trains were delivered every 5 mm until stable triggered and spontaneous population bursts were elicited. The slices were then irradiated with a low power (25 mW) argon laser. No changes in the morphology or number of epileptiform bursts were found while the laser was on. However, when the laser was turned off, there was a highly significant reduction in frequency and morphology of bursts. These results indicate that exposure to light alters epileptiform activity within the hippocampus in vitro, and provides evidence indicating that the central nervous system is photosensitive.

Design of an Electron Beam Pumped High Power Argon Excimer Laser

A procedure for designing an elcctron-beam pumped argon excimer laser is given. Following this procedure, a high power frequency-tunable argon excimer laser has been designed. Experimental data of the argon excimer laser thus designed are compared with our design values. It is proven that the design procedure gives reliable performance prediction. The possibility of high repetition operation of an argon excimer laser is also discussed.

High Power Argon Excimer Laser at 126nm Pumped by Electron Beam

An electron-beam pumped high power argon excimer laser was constructed as a coherent light source for the laser induced fluorescence spectroscopy to measure the concentration of atomic carbon in a fusion-oriented plasma. The laser radiation at 126 nm has been obtained by pumping a commercially purified Ar gas at a pressure of 31 kg/cm2 in a coaxial diode using electron currents of 20∼30 KA and voltages of over 400 KV. The line width of the laser radiation was measured to be 2.5 nm in FWHM and the output laser energy reached to a value of 4.3 mJ, which was 6 times higher than the maximum laser energy reported previously.

High Power Argon Laser Treatment Via Standard Endoscopes

With minimal transmission loss a high power argon laser (10 w) was coupled to a waveguide consisting of a flexible, single, coated, quartz fiber encased in a protective polyethylene tube. This waveguide can be passed down the biopsy channel of any standard fiberoptic endoscope. An aiming light improves accuracy. Safety devices were developed to protect the subject and the operator. Each of 8 heparinized mongrel dogs had three superficial erosions created endoscopically in the fundal gland mucosa by a jet of warm 0.1 N HC1. In each animal two lesions were photocoagulated with the laser and the third was left as a control. The animals were killed at 0, 4, 7, 10, and 14 days, and the erosions were examined histologically. By 14 days all lesions were covered by normal surface epithelium. Parietal and chief cells had returned to untreated erosions at 14 days but not to all lasered lesions. Only rarely did the lasered lesions penetrate through the muscularis mucosae into the submucosa. High power argon laser photocoagulation is now feasible through standard endoscopes. These data are sufficiently promising to encourage further evaluation of laser photocoagulation in a variety of animal models.

Light Intensity Modulation in a Thermal Medium

The intensity of a low power He-Ne laser beam was modulated in a thermal medium consisting of a slab of lead glass by temperature fluctuations caused by the absorption of light from a higher power argon laser. Close agreement between experiment and analytical calculations has been obtained. This type of modulation permits the detection of small temperature fluctuations in materials that are partially transmitting to a low power laser.

Frequency Stabilization of a High Power Argon Laser

A technique for frequency stabilizing a high power, single frequency argon laser is described which offers certain advantages over those that have already been reported. This system is capable of maintaining a relative short term frequency stability of the order of +/-2 parts in 10(9) and a long term stability (2 h) of about +/-5 parts in 10(9) for the 5145-A line at a power level of 750 mW. This short and long term stability is achieved by means of a multiple feedback loop composed of an optical cavity discriminator which is stabilized against an iodine vapor absorption line.