The photothermal deflection technique, also known as "mirage effect", is a nondestructive method of evaluating thermal properties of solid, liquid or gaseous species. This technique will be used to detect pollutant absorption. As the deflection is stronger in liquids than gases, we will first consider the deflection in paraffin oil. We consider a medium that is heated by a modulated laser diode...

Thin film ablation with pulsed nanosecond lasers can benefit from the use of beam shaping optics to transform the Gaussian beam profile with a circular footprint into a Top-Hat beam profile with a rectangular footprint. In general, the quality of the transformed beam profile depends strongly on the beam alignment of the entire laser system. In particular, the adjustment of the beam shaping elem...

Experimental laser beam profiles often deviate somewhat from the ideal Gaussian shape of the axisymmetric TEM(00) laser mode. To take these deviations into account when calculating light scattering of an off-axis beam by a spherical particle, we use our phase-modeling method to approximate the beam-shape coefficients in the partial wave expansion of an experimental laser beam. We then use these...

Laser marking is the modern industrial application for non-contact surface modification. An incidence of a laser beam on the marked surface causes material and structural changes, which lead to optical changes of the surface. The processes during the laser-surface interaction can also affect other surface properties, especially corrosion properties in the case of stainless steel. Laser marking ...

We demonstrate that a laser beam converging from a specific transverse mode is a bottle beam, as described in J. Opt. Soc. Am. B 20, 1220 (2003). To our knowledge, this is the first time that a bottle beam has been generated directly from a laser. By calculating the radiation forces on a dielectric Rayleigh sphere in the bottle beam, we show that the single beam can trap high-refractive-index p...

treatment with antimicrobial chemotherapeutic agents, alternative approaches such as lethal photosensitization are being used. the aim of this study was to evaluate the effect of visible light and laser beam radiation in conjugation with three different photosensitizers on the survival of two main periodontopathogenic bacteria including porphyromonas gingivalis and fusobacterium nucleatum in di...

Holographic interconnection schemes for high-speed data transfer have been demonstrated by other researchers. Because holographic recording materials presently available are sensitive to the visible spectrum but not to the near infrared, these studies used bulky gas lasers. Visible laser diodes, as they become available, will likely become a preferred source in a practical system because of the...

The rapid melting of silicon film due to the absorption of a CW laser beam radiation is studied. The silicon film melting and recrystallization is mainly controlled by the temperature distribution in the semiconductor. The enthalpy technique for the solution of phase change problems is used in an explicit finite difference form to calculate the transient temperature distribution in the silicon ...

The laser beam welding of silica represents an innovative alternative to traditional oxyacetylene welding. The application of this technology allows an economic bonding of silica components, which raises the standards of joint qualities to a new level. In a research project, the Bauhaus-Universität Weimar analyzes the CO2-laser beam welding of silica elements numerically and experimentally in c...