Ruby laser

About: Ruby laser is a research topic. Over the lifetime, 2474 publications have been published within this topic receiving 38933 citations. The topic is also known as: corundum laser & ruby rod.

A preliminary investigation of the use of focused laser beams for minimum ignition energy studies

Abstract: The plasma produced by focusing a passively Q-switched 30 J ruby laser beam is studied as regards its suitability for minimum ignition energy measurement. By comparison with electric spark discharges, it would appear to offer shorter times and smaller volumes of the initiating plasma, as well as freedom from energy losses to electrodes and elsewhere within the circuit. The growth of the initiating plasma as well as that of the flame kernel are studied as a function of pressure and composition, the former using an optical delay line with a schlieren system and the latter by high-speed schlieren streak photography. It is found that the difficulties of the method are associated with the finite duration of the laser pulse. In the time between the onset of breakdown and the end of the pulse the plasma front facing the incident beam absorbs the incoming energy, leading to the production of an extended and unsymmetrical initiating source, an absorption threshold which may already be in excess of the minimum ignition energy, and the formation of a blast wave which may be powerful enough to initiate a detonation rather than a deflagration. For a pulse of approx. 20 nano second half width these effects become serious above about half an atmosphere for stoichiometric methane-air mixtures. For lower pressures, or near limit mixtures, the promise of the method is borne out and both ignition energies and quenching distances fall below those determined by the electric spark method. For higher pressures and faster reacting mixtures it will be necessary to decrease the duration of the laser pulse and the size of the plasma.

Observation of Laser-induced Explosion of Solid Materials and Correlation with Theory

Abstract: A high speed framing camera was used to record the sequential steps of the start, development, and cessation of a highly energetic plume of matter caused by a ruby laser pulse of intensity of the order of 10(7) W/cm(2) on alumina ceramic and copper materials. The results of the experiments have established that the laser intensity and a normalized absorption coefficient are the two most important factors to be considered for any material removal process such as hole drilling. This study has provided the experimental support of a theoretical analysis on laser-induced vaporization and explosion of solid material, developed and published previously.

Method and apparatus for skin rejuvination and wrinkle smoothing

Abstract: A method and apparatus for treating skin including applying pulsed light to the skin for heating and shrinking collagen within the skin, thereby reviving the elasticity of the collagen and of the skin. The epidermis and outer layers of the skin may be protected by cooling with a transparent substance, such as ice, gel or crystal. The temperature distribution within the skin is controlled by controlling the delay between the time the coolant is applied, and the time the light is applied, by controlling the pulse duration and applying multiple pulses, and by filtering the light and controlling the radiation spectrum. Preferably, the spectrum includes light having a wavelength in the range of 500-2000 nm. The pulsed light may be incoherent, such as that produced by a flashlamp, or coherent, such as that produced by a Nd(Yag) laser,an Alexandrite laser, a Diode laser, an Er:glass laser or a ruby laser, and may be directed to the skin using a flexible or rigid light guide.

Effects of pulsed ruby‐laser annealing on As and Sb implanted silicon

Abstract: The effects of pulsed (Q‐switched) ruby‐laser annealing of arsenic‐ and antimony‐implanted silicon (1×1015 to ∼2×1016 cm−2) has been studied by Rutherford ion backscattering, TEM, and ion channeling. The laser pulses were of ∼50‐nsec time width and of 1.5–1.7 J/cm2 energy density. Analysis of the dopant profiles before and after annealing leads to the conclusion that the dopants diffuse under normal kinetics in a melted silicon layer over an average time interval of about 0.27‐μsec after the laser power has been absorbed. Recrystallization of the melt layer is by liquid‐phase epitaxial regrowth from the substrate. The recrystallized zone is found to be free of significant structural defects for all specimens except the very highest antimony doses, in which case some near‐surface (∼400 A) precipitation at dislocations is observed. Atom‐location measurements reveal that 98–99% of the retained dopant is in substitutional lattice sites even when the dopant concentration greatly exceeds the limit of solid solu...

Pulsed laser melting of amorphous silicon layers

Abstract: We have investigated microstructural changes in self‐implanted and arsenic‐ion‐implanted amorphous silicon layers as a function of energy density after pulsed ruby laser irradiation, using cross‐section transmission electron microscopy and Rutherford backscattering. In specimens irradiated with energy densities less than that required to cause complete annealing, we have identified two distinct regions; the first one consisting of fine polycrystals and the second one consisting of large polycrystals. The changes in thickness of these two regions as a function of pulse energy density are described. Concomitant changes in arsenic concentration profiles are consistent with diffusion in liquid silicon. From the profile broadening in the large polycrystalline region, the crystal growth velocity was estimated to be 4–6 ms−1.