Abstract: A single crystal orthodontic bracket is disclosed which is provided with an outer protective layer of a polycrystalline material so as to provide fracture toughness of the orthodontic bracket.

Abstract: A sapphire orthodontic bracket with enhanced tolerance to fabrication, installation and use is fabricated such that the "r" planes of the sapphire are at substantially equal angles to the longitudinal axis of the arch wire groove of the bracket.

Abstract: A crystalline orthodontic bracket with enhanced tolerance to fabrication, installation and use is composed of zirconia, yttria, magnesia or strontium titanate.

Abstract: A high gain optically pumped laser device includes a mask having cut-out portions defining a given pattern disposed in the resonant optical cavity defined between end mirrors at opposite ends of the laser material. Each of the end mirrors is equivalent to an optically flat reflecting surface such that only cross-sectional portions in the laser material similar to the pattern are stimulated to emit output laser radiation. This stimulated emission has a high energy density and may be directly radiated to a target surface to alter the surface in a manner corresponding to the given pattern. The alteration may take the form of actual vaporization, heating, or oxidation of portions of the surface. Thus carefully controlled engraving type processes or other processes involving a physical alteration of a surface such as the drilling of square or unusually shaped holes as determined by the pattern can be carried out.

Abstract: Method for producing massive unicrystalline R-plane alpha alumina of circular cross-section from an alumina melt by controlled rotation of the seed rod upon which the alpha alumina is solidified and crystallized.