There is provided a cylinder including a first cylinder having an inner surface exposed; and a second cylinder joined to an outer surface of the first cylinder, the second cylinder containing alumina as a main component, the first cylinder containing yttrium-containing oxide as a main component.

There is provided a cylinder including a first cylinder having an inner surface exposed; and a second cylinder joined to an outer surface of the first cylinder, the second cylinder containing alumina as a main component, the first cylinder containing yttrium-containing oxide as a main component.

Techniques and architecture are disclosed for managing alkali vapor concentration in a lasing gas at non-condensing levels. In some instances, the disclosed techniques/architecture can be used to control and/or stabilize the concentration of alkali vapor in a lasing gas volume to any desired fraction of its saturation value under dynamically changing thermal loads. In some such instances, the concentration of alkali vapor in a given lasing gas volume can be maintained at a value which is sufficiently far from the saturation point to prevent or otherwise reduce condensation of the alkali vapor, for example, upon accelerating the lasing gas through a pressure drop into an optical pumping cavity of an alkali vapor laser system (e.g., such as a diode-pumped alkali laser, or DPAL, system). In some instances, the disclosed techniques/architecture can be used to establish a temperature gradient and/or an alkali vapor concentration gradient in the flowing lasing gas volume.

Techniques and architecture are disclosed for managing alkali vapor concentration in a lasing gas at non-condensing levels. In some instances, the disclosed techniques/architecture can be used to control and/or stabilize the concentration of alkali vapor in a lasing gas volume to any desired fraction of its saturation value under dynamically changing thermal loads. In some such instances, the concentration of alkali vapor in a given lasing gas volume can be maintained at a value which is sufficiently far from the saturation point to prevent or otherwise reduce condensation of the alkali vapor, for example, upon accelerating the lasing gas through a pressure drop into an optical pumping cavity of an alkali vapor laser system (e.g., such as a diode-pumped alkali laser, or DPAL, system). In some instances, the disclosed techniques/architecture can be used to establish a temperature gradient and/or an alkali vapor concentration gradient in the flowing lasing gas volume.

Techniques and architecture are disclosed for preserving optical surfaces (e.g., windows, coatings, etc.) in a flowing gas amplifier laser system, such as a diode-pumped alkali laser (DPAL) system. In some instances, the disclosed techniques/architecture can be used, for example, to protect optical surfaces in a DPAL system from: (1) chemical attack by pump-bleached alkali vapor atoms and/or ions; and/or (2) fouling by adherence thereto of reaction products/soot produced in the DPAL. Also, in some instances, the disclosed techniques/architecture can be used to substantially match the geometry of the pumping volume with that of the lasing volume, thereby minimizing or otherwise reducing the effects of amplified spontaneous emission (ASE) on DPAL output power. Furthermore, in some cases, the disclosed techniques/architecture can be used to provide a DPAL system capable of producing a beam output power in the range of about 20 kW to 10 MW, or greater.

A gas laser oscillation apparatus of orthogonal excitation type includes an electric discharge region having a pair of electric discharge electrodes, an axial flow blower having a plurality of rotor vanes and working by a permanent magnet motor, a first heat exchanger having a plurality of cooling fins, the cooling fins arranged on a plane perpendicular to an optical axis, a second heat exchanger having a plurality of cooling fins, the cooling fins arranged on a plane perpendicular to the optical axis, a gas duct having a gas passageway and arranged between the electric discharge region and the first heat exchanger, the axial flow blower being arranged on the gas passageway. The axial flow blower is arranged on a windward side of the first heat exchanger. The second heat exchanger is arranged on a windward side of the axial flow blower.