US 4,054,846 A · Transverse-excitation laser with preionization

Abstract

Preionization is achieved in transverse-discharge gaseous lasers by means of the Malter effect. In two embodiments, the preionization is achieved either with a metal electrode which is the cathode during preionization and then is the anode during the subsequent pumping phase, or by means of a separate set of preionization electrodes. These preionization cathodes are metal electrodes, such as aluminum or tantalum electrodes, exhibiting high secondary electron emission by the Malter effect. High-field electron emission from these preionization cathodes is inherently possible because of a thin insulating layer on the surface. This layer separates positive ions attracted to the surface from the conducting metal and thereby creates a very high field gradient over a very short distance. In a preferred embodiment, uniform initial ionization is created during the preionization phase of operation; and the excitation is supplied by an electric field which is lower than that required to sustain the discharge; and the active medium is enclosed in an optical waveguide free of interfering structure.

Claims20

Dependent claims

A transverse excitation laser comprising

means defining an optical axis along which the laser light propagates,
cathode and anode electrode means positioned in opposed relationship along said optical axis for establishing therealong a transverse electric field,
insulating side wall members forming with said cathode and anode means a waveguide for the laser light,
means for flowing a gaseous medium in said waveguide in the transverse electric field, and
means for exciting said medium to produce a population inversion therein and to stimulate the desired emission of radiation;
characterized in that:
the cathode means includes means for preionizing said medium via the Malter effect;
the exciting means includes means for applying a relatively higher voltage pulse between the opposed cathode and anode electrode means for preionizing said medium within said waveguide, and means for applying a relatively lower voltage between opposed electrode means for sustaining a discharge in the medium within the waveguide;
and the waveguide is free of other preionization means.

6 more elements

A transverse excitation laser comprising

means defining an optical axis along which the laser light propagates,
electrode means positioned in opposed relationship along said optical axis for establishing therealong a transverse electric field, one of said electrode means being a solid base member and the other of said electrode means comprising a plurality of metallic segments, adjacent metallic segments being spaced apart by an interleaved plurality of insulating segments to form a continuous surface,
insulating side wall members forming with said electrode means a waveguide for the laser light,
a gaseous medium for flow in said waveguide in the transverse electric field, and
means for exciting said medium to produce a population inversion and to stimulate the desired emission of radiation,
characterized in that the exciting means includes a first voltage source for applying a relatively higher voltage pulse between the base member as anode and at least some of the metal segments as cathode for preionizing said medium and a second voltage source for applying a relatively lower voltage between said base member as cathode and at least some of the metal segments as anode for sustaining a discharge in said medium, the waveguide being free of other electrode means and opaque to the introduction of free electrons therein and the metal segments include an insulating surface layer for providing secondary electron emission for preionizing the medium.

3 more elements

Dependencies are inferred from the claim text.

Transverse-excitation laser with preionization

Life of this patent

Transverse-excitation laser with preionization

Life of this patent

Abstract

Claims20