USA As Represented by Secretary of the Navy

Union Carbide Chemicals & Plastics

Ramesh Kumar Shori

Michael Johnny Wardlaw

Ralph Steven Kurti

Milan R Kokta

Method and apparatus to generate a composite far field beam having a central null and discrete cylindrical symmetry. A phased array of Gaussian beams was used to form an annular far-field pattern as opposed to the normal peaked pattern in most phased arrays. This annular pattern arises from the radial symmetry of the polarization in each beam. Beams opposite one another in the annulus are polarized in the same direction but are 180&#xb0; out of phase. This causes the center portion of the beam to be a null rather than a peak.

Apparatus and method for producing an annular composite far-field patterned beam(s)

A phased array of Gaussian beams was used to form an annular far-field pattern as opposed to the normal peaked pattern in most phased arrays. This annular pattern arises from the radial symmetry of the polarization in each beam. Beams opposite one another in the annulus are polarized in the same direction but are 180&#xb0; out of phase. This causes the center portion of the beam to be a null rather than a peak.

Apparatus and method for producing an annular far-field patterned beam(s)

A Cr/Tm/Er-doped, yttrium- or lutetium-garnet host material crystal for a solid-state laser, wherein about 3 to about 8 atomic percent of the yttrium or lutetium, respectively, crystallographic sites are occupied by Tm.sup.3+ ions, about 7 to about 22 atomic percent of the yttrium or lutetium, respectively, crystallographic sites are occupied by Er.sup.3+ ions, and about 0.6 to about 1.6 atomic percent of the octahedral sites of the garnet structure are occupied by Cr.sup.3+ ions, which crystal lases under the influence of a pumping means at a wavelength of no more than about 2.7.mu..

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Burbank, CA, United States of America

Ramesh Kumar Shori