Professor Townsend Receives Sixth Patent

Dr. Lee Townsend, assistant professor of Mathematics in CETA, has been awarded her sixth laser-related patent. She and Ron LaComb, son of Barney School of Business administrator Ron LaComb, received patent 7,492,805 for their invention of a scalable spherical laser.

Their design is unique in that its output radiation is radially diverging; from outside the laser, the beam looks as if it emanates from a point source. This feature contrasts with traditional lasers, which are characterized by well-defined collimated output beams that are focused, not imaged, on a target. Another unique feature of this spherical laser is that the laser’s active volume can be increased without the excitement of additional radial modes. Their laser consists of two concentric spherical shells. Because the spacing between the shells is constant, the radial modes are not affected if the laser is made larger; there is simply more output power. The Townsend-LaComb laser, because of its unique geometry, has the potential to produce significantly higher single-mode output powers that can be imaged—in an ideal system—to a point.

Townsend and LaComb present two techniques to harness the diverging beam. The first uses a reflecting ellipsoid and results in a sub-diffraction spot size. The laser center is placed at one ellipsoid focus and the target at the other, similar to the geometry in the Whispering Gallery in Statuary Hall in the Capitol building in Washington, D.C. This system is thus effectively imaging a point source. Aberrations in the optical train will increase the spot size somewhat, but there will be no spread of energy in the wings of small spot size beams as there is in the traditional focusing of collimated beams to produce a large on-axis spike. A second optical train geometry uses a reflecting parabola to produce a flat-phase collimated output.

The production of a sub-diffraction limited spot size has major implications in the fields of biophotonics and in the life sciences and for photochemical and photo-physical processes, as well as in industrial applications. The ability to increase active volume without altering the radial mode is unique to this laser, and when the laser beam is converted to a collimated beam, it has important, potentially revolutionary implications in the fields of communications, sensing, and high-energy industrial laser applications such as welding and cutting.

A copy of the patent is available on Dr. Townsend’s website, http://uhaweb.hartford.edu/ltownsend/, along with copies of her other five patents.

CETA congratulates Dr. Townsend and Dr. LaComb for their achievement.