Patent attributes
Apparatus, systems, and methods for investigating a subsurface volume of interest from a borehole. Apparatus comprise an enclosure configured for conveyance along the borehole; an acoustic source in the enclosure configured to generate acoustic signals; a lens assembly disposed in the enclosure and next to the acoustic source, the lens assembly being formed of a plurality of lens elements; wherein each lens element comprises a plurality of cells arranged in a curvilinear cell array, each cell formed as a column oriented transverse to a direction of travel of the acoustical signals. The plurality of cells may be arranged according to a conformal mapping geometry, including a canonical Bipolar conformal mapping transformation of constant [u,v] contour lines to [x,y] Cartesian coordinates. A portion of the cells are scaled down in size by a scale factor. The scale factor corresponding to each cell of the portion varies non-monotonically along periodicity lines.
