An optical device, comprising: a frame; a first light generating mechanism operatively connected to the frame; a first lens disposed in a light path of the first light generating mechanism and defining a Cartesian (x,y,z) coordinate system, the first lens having first and second surfaces (110, 120) with x,y coordinates, the second surface defining a multiple-radius curve in an x,y plane, the lens converting light generated by the first light generating mechanism into a first light plane; wherein, the first light generating mechanism and first lens are constructed and positioned to transmit light generated by the first light generating mechanism through the first and second surfaces (110, 120) to create the first light plane; and a self-leveling mechanism operatively mounted to the frame, the self-leveling mechanism tending to orient the first light plane into a predetermined angle relative to horizontal; wherein the x axis of the lens is coaxial to the light path generated by the first light generating mechanism at a point at which the light path intersects the first lens, and wherein the radius of curvature of the second surface increases as the absolute y value increases over at least a portion of the second surface; and wherein the surfaces define a cross-section in an x-y plane that is substantially constant over at least a portion of the z direction length of the first lens, the first and second surfaces (110, 120) of the first lens are shaped and oriented relative to the light path of the first light generating mechanism so as to direct relatively more intense light towards distal ends of the light plane than towards a central portion of the light plane, characterized in that at least a portion of the second surface defines an elliptical curve according to the equation x 2 /a 2 + y 2 /b 2 = 1, wherein a is greater than b, or at least a portion of the second surface defines a non-cylindrical curve according to the equation x = cy 2 / (1+sqrt (1-(1+k) ∗ c 2∗ y 2)) + d ∗ y 4, wherein c, k, and d are constants. a frame; a first light generating mechanism operatively connected to the frame; a first lens disposed in a light path of the first light generating mechanism and defining a Cartesian (x,y,z) coordinate system, the first lens having first and second surfaces (110, 120) with x,y coordinates, the second surface defining a multiple-radius curve in an x,y plane, the lens converting light generated by the first light generating mechanism into a first light plane; wherein, the first light generating mechanism and first lens are constructed and positioned to transmit light generated by the first light generating mechanism through the first and second surfaces (110, 120) to create the first light plane; and a self-leveling mechanism operatively mounted to the frame, the self-leveling mechanism tending to orient the first light plane into a predetermined angle relative to horizontal; wherein the x axis of the lens is coaxial to the light path generated by the first light generating mechanism at a point at which the light path intersects the first lens, and wherein the radius of curvature of the second surface increases as the absolute y value increases over at least a portion of the second surface; and wherein the surfaces define a cross-section in an x-y plane that is substantially constant over at least a portion of the z direction length of the first lens, the first and second surfaces (110, 120) of the first lens are shaped and oriented relative to the light path of the first light generating mechanism so as to direct relatively more intense light towards distal ends of the light plane than towards a central portion of the light plane, characterized in that at least a portion of the second surface defines an elliptical curve according to the equation x 2 /a 2 + y 2 /b 2 = 1, wherein a is greater than b, or at least a portion of the second surface defines a non-cylindrical curve according to the equation x = cy 2 / (1+sqrt (1-(1+k) ∗ c 2∗ y 2)) + d ∗ y 4, wherein c, k, and d are constants.